/*
- * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
+
 package java.lang;
 
 import java.io.InputStream;
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.io.File;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
-import java.net.MalformedURLException;
 import java.net.URL;
 import java.security.AccessController;
 import java.security.AccessControlContext;
 import java.security.CodeSource;
-import java.security.Policy;
 import java.security.PrivilegedAction;
-import java.security.PrivilegedActionException;
-import java.security.PrivilegedExceptionAction;
 import java.security.ProtectionDomain;
 import java.security.cert.Certificate;
+import java.util.ArrayDeque;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.Deque;
 import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.Set;
-import java.util.Stack;
-import java.util.Map;
-import java.util.Vector;
 import java.util.Hashtable;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.Set;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.Vector;
 import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentHashMap;
-import sun.misc.CompoundEnumeration;
-import sun.misc.Resource;
-import sun.misc.URLClassPath;
-import sun.misc.VM;
-import sun.reflect.CallerSensitive;
-import sun.reflect.Reflection;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import jdk.internal.loader.BuiltinClassLoader;
+import jdk.internal.perf.PerfCounter;
+import jdk.internal.loader.BootLoader;
+import jdk.internal.loader.ClassLoaders;
+import jdk.internal.misc.Unsafe;
+import jdk.internal.misc.VM;
+import jdk.internal.ref.CleanerFactory;
+import jdk.internal.reflect.CallerSensitive;
+import jdk.internal.reflect.Reflection;
 import sun.reflect.misc.ReflectUtil;
 import sun.security.util.SecurityConstants;
 
 /**
  * A class loader is an object that is responsible for loading classes. The
- * class <tt>ClassLoader</tt> is an abstract class.  Given the <a
- * href="#name">binary name</a> of a class, a class loader should attempt to
+ * class {@code ClassLoader} is an abstract class.  Given the <a
+ * href="#binary-name">binary name</a> of a class, a class loader should attempt to
  * locate or generate data that constitutes a definition for the class.  A
  * typical strategy is to transform the name into a file name and then read a
  * "class file" of that name from a file system.
  *
- * <p> Every {@link Class <tt>Class</tt>} object contains a {@link
- * Class#getClassLoader() reference} to the <tt>ClassLoader</tt> that defined
+ * <p> Every {@link java.lang.Class Class} object contains a {@link
+ * Class#getClassLoader() reference} to the {@code ClassLoader} that defined
  * it.
  *
- * <p> <tt>Class</tt> objects for array classes are not created by class
+ * <p> {@code Class} objects for array classes are not created by class
  * loaders, but are created automatically as required by the Java runtime.
  * The class loader for an array class, as returned by {@link
  * Class#getClassLoader()} is the same as the class loader for its element
  * type; if the element type is a primitive type, then the array class has no
  * class loader.
  *
- * <p> Applications implement subclasses of <tt>ClassLoader</tt> in order to
+ * <p> Applications implement subclasses of {@code ClassLoader} in order to
  * extend the manner in which the Java virtual machine dynamically loads
  * classes.
  *
  * <p> Class loaders may typically be used by security managers to indicate
  * security domains.
  *
- * <p> The <tt>ClassLoader</tt> class uses a delegation model to search for
- * classes and resources.  Each instance of <tt>ClassLoader</tt> has an
- * associated parent class loader.  When requested to find a class or
- * resource, a <tt>ClassLoader</tt> instance will delegate the search for the
- * class or resource to its parent class loader before attempting to find the
- * class or resource itself.  The virtual machine's built-in class loader,
- * called the "bootstrap class loader", does not itself have a parent but may
- * serve as the parent of a <tt>ClassLoader</tt> instance.
+ * <p> In addition to loading classes, a class loader is also responsible for
+ * locating resources. A resource is some data (a "{@code .class}" file,
+ * configuration data, or an image for example) that is identified with an
+ * abstract '/'-separated path name. Resources are typically packaged with an
+ * application or library so that they can be located by code in the
+ * application or library. In some cases, the resources are included so that
+ * they can be located by other libraries.
+ *
+ * <p> The {@code ClassLoader} class uses a delegation model to search for
+ * classes and resources.  Each instance of {@code ClassLoader} has an
+ * associated parent class loader. When requested to find a class or
+ * resource, a {@code ClassLoader} instance will usually delegate the search
+ * for the class or resource to its parent class loader before attempting to
+ * find the class or resource itself.
  *
  * <p> Class loaders that support concurrent loading of classes are known as
- * <em>parallel capable</em> class loaders and are required to register
- * themselves at their class initialization time by invoking the
- * {@link
- * #registerAsParallelCapable <tt>ClassLoader.registerAsParallelCapable</tt>}
- * method. Note that the <tt>ClassLoader</tt> class is registered as parallel
+ * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class
+ * loaders and are required to register themselves at their class initialization
+ * time by invoking the {@link
+ * #registerAsParallelCapable ClassLoader.registerAsParallelCapable}
+ * method. Note that the {@code ClassLoader} class is registered as parallel
  * capable by default. However, its subclasses still need to register themselves
- * if they are parallel capable. <br>
+ * if they are parallel capable.
  * In environments in which the delegation model is not strictly
  * hierarchical, class loaders need to be parallel capable, otherwise class
  * loading can lead to deadlocks because the loader lock is held for the
  * duration of the class loading process (see {@link #loadClass
- * <tt>loadClass</tt>} methods).
+ * loadClass} methods).
+ *
+ * <h3> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h3>
+ *
+ * The Java run-time has the following built-in class loaders:
+ *
+ * <ul>
+ * <li><p>Bootstrap class loader.
+ *     It is the virtual machine's built-in class loader, typically represented
+ *     as {@code null}, and does not have a parent.</li>
+ * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}.
+ *     All <em>platform classes</em> are visible to the platform class loader
+ *     that can be used as the parent of a {@code ClassLoader} instance.
+ *     Platform classes include Java SE platform APIs, their implementation
+ *     classes and JDK-specific run-time classes that are defined by the
+ *     platform class loader or its ancestors.
+ *     <p> To allow for upgrading/overriding of modules defined to the platform
+ *     class loader, and where upgraded modules read modules defined to class
+ *     loaders other than the platform class loader and its ancestors, then
+ *     the platform class loader may have to delegate to other class loaders,
+ *     the application class loader for example.
+ *     In other words, classes in named modules defined to class loaders
+ *     other than the platform class loader and its ancestors may be visible
+ *     to the platform class loader. </li>
+ * <li><p>{@linkplain #getSystemClassLoader() System class loader}.
+ *     It is also known as <em>application class loader</em> and is distinct
+ *     from the platform class loader.
+ *     The system class loader is typically used to define classes on the
+ *     application class path, module path, and JDK-specific tools.
+ *     The platform class loader is a parent or an ancestor of the system class
+ *     loader that all platform classes are visible to it.</li>
+ * </ul>
  *
  * <p> Normally, the Java virtual machine loads classes from the local file
- * system in a platform-dependent manner.  For example, on UNIX systems, the
- * virtual machine loads classes from the directory defined by the
- * <tt>CLASSPATH</tt> environment variable.
- *
- * <p> However, some classes may not originate from a file; they may originate
+ * system in a platform-dependent manner.
+ * However, some classes may not originate from a file; they may originate
  * from other sources, such as the network, or they could be constructed by an
  * application.  The method {@link #defineClass(String, byte[], int, int)
- * <tt>defineClass</tt>} converts an array of bytes into an instance of class
- * <tt>Class</tt>. Instances of this newly defined class can be created using
- * {@link Class#newInstance <tt>Class.newInstance</tt>}.
+ * defineClass} converts an array of bytes into an instance of class
+ * {@code Class}. Instances of this newly defined class can be created using
+ * {@link Class#newInstance Class.newInstance}.
  *
  * <p> The methods and constructors of objects created by a class loader may
  * reference other classes.  To determine the class(es) referred to, the Java
- * virtual machine invokes the {@link #loadClass <tt>loadClass</tt>} method of
+ * virtual machine invokes the {@link #loadClass loadClass} method of
  * the class loader that originally created the class.
  *
  * <p> For example, an application could create a network class loader to
  * download class files from a server.  Sample code might look like:
  *
  * <blockquote><pre>
  *   ClassLoader loader&nbsp;= new NetworkClassLoader(host,&nbsp;port);
  *   Object main&nbsp;= loader.loadClass("Main", true).newInstance();
  *       &nbsp;.&nbsp;.&nbsp;.
  * </pre></blockquote>
  *
  * <p> The network class loader subclass must define the methods {@link
- * #findClass <tt>findClass</tt>} and <tt>loadClassData</tt> to load a class
+ * #findClass findClass} and {@code loadClassData} to load a class
  * from the network.  Once it has downloaded the bytes that make up the class,
- * it should use the method {@link #defineClass <tt>defineClass</tt>} to
+ * it should use the method {@link #defineClass defineClass} to
  * create a class instance.  A sample implementation is:
  *
  * <blockquote><pre>
  *     class NetworkClassLoader extends ClassLoader {
  *         String host;
  *         int port;
  *
  *         public Class findClass(String name) {
  *             byte[] b = loadClassData(name);
  *             return defineClass(name, b, 0, b.length);
  *         }
  *
  *         private byte[] loadClassData(String name) {
  *             // load the class data from the connection
  *             &nbsp;.&nbsp;.&nbsp;.
  *         }
  *     }
  * </pre></blockquote>
  *
- * <h3> <a name="name">Binary names</a> </h3>
+ * <h3> <a id="binary-name">Binary names</a> </h3>
  *
- * <p> Any class name provided as a {@link String} parameter to methods in
- * <tt>ClassLoader</tt> must be a binary name as defined by
+ * <p> Any class name provided as a {@code String} parameter to methods in
+ * {@code ClassLoader} must be a binary name as defined by
  * <cite>The Java&trade; Language Specification</cite>.
  *
  * <p> Examples of valid class names include:
  * <blockquote><pre>
  *   "java.lang.String"
  *   "javax.swing.JSpinner$DefaultEditor"
  *   "java.security.KeyStore$Builder$FileBuilder$1"
  *   "java.net.URLClassLoader$3$1"
  * </pre></blockquote>
  *
+ * <p> Any package name provided as a {@code String} parameter to methods in
+ * {@code ClassLoader} must be either the empty string (denoting an unnamed package)
+ * or a fully qualified name as defined by
+ * <cite>The Java&trade; Language Specification</cite>.
+ *
+ * @jls 6.7  Fully Qualified Names
+ * @jls 13.1 The Form of a Binary
  * @see      #resolveClass(Class)
  * @since 1.0
+ * @revised 9
+ * @spec JPMS
  */
 public abstract class ClassLoader {
 
     private static native void registerNatives();
     static {
         registerNatives();
     }
 
     // The parent class loader for delegation
     // Note: VM hardcoded the offset of this field, thus all new fields
     // must be added *after* it.
     private final ClassLoader parent;
 
+    // class loader name
+    private final String name;
+
+    // the unnamed module for this ClassLoader
+    private final Module unnamedModule;
+
+    // a string for exception message printing
+    private final String nameAndId;
+
     /**
      * Encapsulates the set of parallel capable loader types.
      */
     private static class ParallelLoaders {
         private ParallelLoaders() {}
 
         // the set of parallel capable loader types
         private static final Set<Class<? extends ClassLoader>> loaderTypes =
-            Collections.newSetFromMap(
-                new WeakHashMap<Class<? extends ClassLoader>, Boolean>());
+            Collections.newSetFromMap(new WeakHashMap<>());
         static {
             synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
         }
 
         /**
-         * Registers the given class loader type as parallel capabale.
+         * Registers the given class loader type as parallel capable.
          * Returns {@code true} is successfully registered; {@code false} if
          * loader's super class is not registered.
          */
         static boolean register(Class<? extends ClassLoader> c) {
             synchronized (loaderTypes) {
                 if (loaderTypes.contains(c.getSuperclass())) {
                     // register the class loader as parallel capable
                     // if and only if all of its super classes are.
                     // Note: given current classloading sequence, if
                     // the immediate super class is parallel capable,
                     // all the super classes higher up must be too.
                     loaderTypes.add(c);
                     return true;
                 } else {
                     return false;
                 }
             }
         }
 
         /**
          * Returns {@code true} if the given class loader type is
          * registered as parallel capable.
          */
         static boolean isRegistered(Class<? extends ClassLoader> c) {
             synchronized (loaderTypes) {
                 return loaderTypes.contains(c);
             }
         }
     }
 
     // Maps class name to the corresponding lock object when the current
     // class loader is parallel capable.
     // Note: VM also uses this field to decide if the current class loader
     // is parallel capable and the appropriate lock object for class loading.
     private final ConcurrentHashMap<String, Object> parallelLockMap;
 
-    // Hashtable that maps packages to certs
+    // Maps packages to certs
     private final Map <String, Certificate[]> package2certs;
 
     // Shared among all packages with unsigned classes
     private static final Certificate[] nocerts = new Certificate[0];
 
     // The classes loaded by this class loader. The only purpose of this table
     // is to keep the classes from being GC'ed until the loader is GC'ed.
     private final Vector<Class<?>> classes = new Vector<>();
 
     // The "default" domain. Set as the default ProtectionDomain on newly
     // created classes.
     private final ProtectionDomain defaultDomain =
         new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
                              null, this, null);
 
     // Invoked by the VM to record every loaded class with this loader.
     void addClass(Class<?> c) {
         classes.addElement(c);
     }
 
-    // The packages defined in this class loader.  Each package name is mapped
-    // to its corresponding Package object.
-    // @GuardedBy("itself")
-    private final HashMap<String, Package> packages = new HashMap<>();
+    // The packages defined in this class loader.  Each package name is
+    // mapped to its corresponding NamedPackage object.
+    //
+    // The value is a Package object if ClassLoader::definePackage,
+    // Class::getPackage, ClassLoader::getDefinePackage(s) or
+    // Package::getPackage(s) method is called to define it.
+    // Otherwise, the value is a NamedPackage object.
+    private final ConcurrentHashMap<String, NamedPackage> packages
+            = new ConcurrentHashMap<>();
+
+    /*
+     * Returns a named package for the given module.
+     */
+    private NamedPackage getNamedPackage(String pn, Module m) {
+        NamedPackage p = packages.get(pn);
+        if (p == null) {
+            p = new NamedPackage(pn, m);
+
+            NamedPackage value = packages.putIfAbsent(pn, p);
+            if (value != null) {
+                // Package object already be defined for the named package
+                p = value;
+                // if definePackage is called by this class loader to define
+                // a package in a named module, this will return Package
+                // object of the same name.  Package object may contain
+                // unexpected information but it does not impact the runtime.
+                // this assertion may be helpful for troubleshooting
+                assert value.module() == m;
+            }
+        }
+        return p;
+    }
 
     private static Void checkCreateClassLoader() {
+        return checkCreateClassLoader(null);
+    }
+
+    private static Void checkCreateClassLoader(String name) {
+        if (name != null && name.isEmpty()) {
+            throw new IllegalArgumentException("name must be non-empty or null");
+        }
+
         SecurityManager security = System.getSecurityManager();
         if (security != null) {
             security.checkCreateClassLoader();
         }
         return null;
     }
 
-    private ClassLoader(Void unused, ClassLoader parent) {
+    private ClassLoader(Void unused, String name, ClassLoader parent) {
+        this.name = name;
         this.parent = parent;
+        this.unnamedModule = new Module(this);
         if (ParallelLoaders.isRegistered(this.getClass())) {
             parallelLockMap = new ConcurrentHashMap<>();
             package2certs = new ConcurrentHashMap<>();
             assertionLock = new Object();
         } else {
             // no finer-grained lock; lock on the classloader instance
             parallelLockMap = null;
             package2certs = new Hashtable<>();
             assertionLock = this;
         }
+        this.nameAndId = nameAndId(this);
+    }
+
+    /**
+     * If the defining loader has a name explicitly set then
+     *       '<loader-name>' @<id>
+     * If the defining loader has no name then
+     *       <qualified-class-name> @<id>
+     * If it's built-in loader then omit `@<id>` as there is only one instance.
+     */
+    private static String nameAndId(ClassLoader ld) {
+        String nid = ld.getName() != null ? "\'" + ld.getName() + "\'"
+                                          : ld.getClass().getName();
+        if (!(ld instanceof BuiltinClassLoader)) {
+            String id = Integer.toHexString(System.identityHashCode(ld));
+            nid = nid + " @" + id;
+        }
+        return nid;
+    }
+
+    /**
+     * Creates a new class loader of the specified name and using the
+     * specified parent class loader for delegation.
+     *
+     * @apiNote If the parent is specified as {@code null} (for the
+     * bootstrap class loader) then there is no guarantee that all platform
+     * classes are visible.
+     *
+     * @param  name   class loader name; or {@code null} if not named
+     * @param  parent the parent class loader
+     *
+     * @throws IllegalArgumentException if the given name is empty.
+     *
+     * @throws SecurityException
+     *         If a security manager exists and its
+     *         {@link SecurityManager#checkCreateClassLoader()}
+     *         method doesn't allow creation of a new class loader.
+     *
+     * @since  9
+     * @spec JPMS
+     */
+    protected ClassLoader(String name, ClassLoader parent) {
+        this(checkCreateClassLoader(name), name, parent);
     }
 
     /**
      * Creates a new class loader using the specified parent class loader for
      * delegation.
      *
      * <p> If there is a security manager, its {@link
-     * SecurityManager#checkCreateClassLoader()
-     * <tt>checkCreateClassLoader</tt>} method is invoked.  This may result in
-     * a security exception.  </p>
+     * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method
+     * is invoked.  This may result in a security exception.  </p>
+     *
+     * @apiNote If the parent is specified as {@code null} (for the
+     * bootstrap class loader) then there is no guarantee that all platform
+     * classes are visible.
      *
      * @param  parent
      *         The parent class loader
      *
      * @throws  SecurityException
      *          If a security manager exists and its
-     *          <tt>checkCreateClassLoader</tt> method doesn't allow creation
+     *          {@code checkCreateClassLoader} method doesn't allow creation
      *          of a new class loader.
      *
      * @since  1.2
      */
     protected ClassLoader(ClassLoader parent) {
-        this(checkCreateClassLoader(), parent);
+        this(checkCreateClassLoader(), null, parent);
     }
 
     /**
-     * Creates a new class loader using the <tt>ClassLoader</tt> returned by
+     * Creates a new class loader using the {@code ClassLoader} returned by
      * the method {@link #getSystemClassLoader()
-     * <tt>getSystemClassLoader()</tt>} as the parent class loader.
+     * getSystemClassLoader()} as the parent class loader.
      *
      * <p> If there is a security manager, its {@link
      * SecurityManager#checkCreateClassLoader()
-     * <tt>checkCreateClassLoader</tt>} method is invoked.  This may result in
+     * checkCreateClassLoader} method is invoked.  This may result in
      * a security exception.  </p>
      *
      * @throws  SecurityException
      *          If a security manager exists and its
-     *          <tt>checkCreateClassLoader</tt> method doesn't allow creation
+     *          {@code checkCreateClassLoader} method doesn't allow creation
      *          of a new class loader.
      */
     protected ClassLoader() {
-        this(checkCreateClassLoader(), getSystemClassLoader());
+        this(checkCreateClassLoader(), null, getSystemClassLoader());
+    }
+
+    /**
+     * Returns the name of this class loader or {@code null} if
+     * this class loader is not named.
+     *
+     * @apiNote This method is non-final for compatibility.  If this
+     * method is overridden, this method must return the same name
+     * as specified when this class loader was instantiated.
+     *
+     * @return name of this class loader; or {@code null} if
+     * this class loader is not named.
+     *
+     * @since 9
+     * @spec JPMS
+     */
+    public String getName() {
+        return name;
+    }
+
+    // package-private used by StackTraceElement to avoid
+    // calling the overrideable getName method
+    final String name() {
+        return name;
     }
 
     // -- Class --
 
     /**
-     * Loads the class with the specified <a href="#name">binary name</a>.
+     * Loads the class with the specified <a href="#binary-name">binary name</a>.
      * This method searches for classes in the same manner as the {@link
      * #loadClass(String, boolean)} method.  It is invoked by the Java virtual
      * machine to resolve class references.  Invoking this method is equivalent
-     * to invoking {@link #loadClass(String, boolean) <tt>loadClass(name,
-     * false)</tt>}.
+     * to invoking {@link #loadClass(String, boolean) loadClass(name,
+     * false)}.
      *
      * @param  name
-     *         The <a href="#name">binary name</a> of the class
+     *         The <a href="#binary-name">binary name</a> of the class
      *
-     * @return  The resulting <tt>Class</tt> object
+     * @return  The resulting {@code Class} object
      *
      * @throws  ClassNotFoundException
      *          If the class was not found
      */
     public Class<?> loadClass(String name) throws ClassNotFoundException {
         return loadClass(name, false);
     }
 
     /**
-     * Loads the class with the specified <a href="#name">binary name</a>.  The
+     * Loads the class with the specified <a href="#binary-name">binary name</a>.  The
      * default implementation of this method searches for classes in the
      * following order:
      *
      * <ol>
      *
      *   <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
      *   has already been loaded.  </p></li>
      *
-     *   <li><p> Invoke the {@link #loadClass(String) <tt>loadClass</tt>} method
-     *   on the parent class loader.  If the parent is <tt>null</tt> the class
-     *   loader built-in to the virtual machine is used, instead.  </p></li>
+     *   <li><p> Invoke the {@link #loadClass(String) loadClass} method
+     *   on the parent class loader.  If the parent is {@code null} the class
+     *   loader built into the virtual machine is used, instead.  </p></li>
      *
      *   <li><p> Invoke the {@link #findClass(String)} method to find the
      *   class.  </p></li>
      *
      * </ol>
      *
      * <p> If the class was found using the above steps, and the
-     * <tt>resolve</tt> flag is true, this method will then invoke the {@link
-     * #resolveClass(Class)} method on the resulting <tt>Class</tt> object.
+     * {@code resolve} flag is true, this method will then invoke the {@link
+     * #resolveClass(Class)} method on the resulting {@code Class} object.
      *
-     * <p> Subclasses of <tt>ClassLoader</tt> are encouraged to override {@link
+     * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link
      * #findClass(String)}, rather than this method.  </p>
      *
      * <p> Unless overridden, this method synchronizes on the result of
-     * {@link #getClassLoadingLock <tt>getClassLoadingLock</tt>} method
+     * {@link #getClassLoadingLock getClassLoadingLock} method
      * during the entire class loading process.
      *
      * @param  name
-     *         The <a href="#name">binary name</a> of the class
+     *         The <a href="#binary-name">binary name</a> of the class
      *
      * @param  resolve
-     *         If <tt>true</tt> then resolve the class
+     *         If {@code true} then resolve the class
      *
-     * @return  The resulting <tt>Class</tt> object
+     * @return  The resulting {@code Class} object
      *
      * @throws  ClassNotFoundException
      *          If the class could not be found
      */
     protected Class<?> loadClass(String name, boolean resolve)
         throws ClassNotFoundException
     {
         synchronized (getClassLoadingLock(name)) {
             // First, check if the class has already been loaded
             Class<?> c = findLoadedClass(name);
             if (c == null) {
                 long t0 = System.nanoTime();
                 try {
                     if (parent != null) {
                         c = parent.loadClass(name, false);
                     } else {
                         c = findBootstrapClassOrNull(name);
                     }
                 } catch (ClassNotFoundException e) {
                     // ClassNotFoundException thrown if class not found
                     // from the non-null parent class loader
                 }
 
                 if (c == null) {
                     // If still not found, then invoke findClass in order
                     // to find the class.
                     long t1 = System.nanoTime();
                     c = findClass(name);
 
                     // this is the defining class loader; record the stats
-                    sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
-                    sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
-                    sun.misc.PerfCounter.getFindClasses().increment();
+                    PerfCounter.getParentDelegationTime().addTime(t1 - t0);
+                    PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
+                    PerfCounter.getFindClasses().increment();
                 }
             }
             if (resolve) {
                 resolveClass(c);
             }
             return c;
         }
     }
 
     /**
+     * Loads the class with the specified <a href="#binary-name">binary name</a>
+     * in a module defined to this class loader.  This method returns {@code null}
+     * if the class could not be found.
+     *
+     * @apiNote This method does not delegate to the parent class loader.
+     *
+     * @implSpec The default implementation of this method searches for classes
+     * in the following order:
+     *
+     * <ol>
+     *   <li>Invoke {@link #findLoadedClass(String)} to check if the class
+     *   has already been loaded.</li>
+     *   <li>Invoke the {@link #findClass(String, String)} method to find the
+     *   class in the given module.</li>
+     * </ol>
+     *
+     * @param  module
+     *         The module
+     * @param  name
+     *         The <a href="#binary-name">binary name</a> of the class
+     *
+     * @return The resulting {@code Class} object in a module defined by
+     *         this class loader, or {@code null} if the class could not be found.
+     */
+    final Class<?> loadClass(Module module, String name) {
+        synchronized (getClassLoadingLock(name)) {
+            // First, check if the class has already been loaded
+            Class<?> c = findLoadedClass(name);
+            if (c == null) {
+                c = findClass(module.getName(), name);
+            }
+            if (c != null && c.getModule() == module) {
+                return c;
+            } else {
+                return null;
+            }
+        }
+    }
+
+    /**
      * Returns the lock object for class loading operations.
      * For backward compatibility, the default implementation of this method
      * behaves as follows. If this ClassLoader object is registered as
      * parallel capable, the method returns a dedicated object associated
      * with the specified class name. Otherwise, the method returns this
      * ClassLoader object.
      *
      * @param  className
      *         The name of the to-be-loaded class
      *
      * @return the lock for class loading operations
      *
      * @throws NullPointerException
-     *         If registered as parallel capable and <tt>className</tt> is null
+     *         If registered as parallel capable and {@code className} is null
      *
      * @see #loadClass(String, boolean)
      *
      * @since  1.7
      */
     protected Object getClassLoadingLock(String className) {
         Object lock = this;
         if (parallelLockMap != null) {
             Object newLock = new Object();
             lock = parallelLockMap.putIfAbsent(className, newLock);
             if (lock == null) {
                 lock = newLock;
             }
         }
         return lock;
     }
 
-    // This method is invoked by the virtual machine to load a class.
-    private Class<?> loadClassInternal(String name)
-        throws ClassNotFoundException
-    {
-        // For backward compatibility, explicitly lock on 'this' when
-        // the current class loader is not parallel capable.
-        if (parallelLockMap == null) {
-            synchronized (this) {
-                 return loadClass(name);
-            }
-        } else {
-            return loadClass(name);
-        }
-    }
-
     // Invoked by the VM after loading class with this loader.
     private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
         final SecurityManager sm = System.getSecurityManager();
         if (sm != null) {
             if (ReflectUtil.isNonPublicProxyClass(cls)) {
                 for (Class<?> intf: cls.getInterfaces()) {
                     checkPackageAccess(intf, pd);
                 }
                 return;
             }
 
-            final String name = cls.getName();
-            final int i = name.lastIndexOf('.');
-            if (i != -1) {
-                AccessController.doPrivileged(new PrivilegedAction<Void>() {
+            final String packageName = cls.getPackageName();
+            if (!packageName.isEmpty()) {
+                AccessController.doPrivileged(new PrivilegedAction<>() {
                     public Void run() {
-                        sm.checkPackageAccess(name.substring(0, i));
+                        sm.checkPackageAccess(packageName);
                         return null;
                     }
                 }, new AccessControlContext(new ProtectionDomain[] {pd}));
             }
         }
     }
 
     /**
-     * Finds the class with the specified <a href="#name">binary name</a>.
+     * Finds the class with the specified <a href="#binary-name">binary name</a>.
      * This method should be overridden by class loader implementations that
      * follow the delegation model for loading classes, and will be invoked by
-     * the {@link #loadClass <tt>loadClass</tt>} method after checking the
-     * parent class loader for the requested class.  The default implementation
-     * throws a <tt>ClassNotFoundException</tt>.
+     * the {@link #loadClass loadClass} method after checking the
+     * parent class loader for the requested class.
+     *
+     * @implSpec The default implementation throws {@code ClassNotFoundException}.
      *
      * @param  name
-     *         The <a href="#name">binary name</a> of the class
+     *         The <a href="#binary-name">binary name</a> of the class
      *
-     * @return  The resulting <tt>Class</tt> object
+     * @return  The resulting {@code Class} object
      *
      * @throws  ClassNotFoundException
      *          If the class could not be found
      *
      * @since  1.2
      */
     protected Class<?> findClass(String name) throws ClassNotFoundException {
         throw new ClassNotFoundException(name);
     }
 
     /**
-     * Converts an array of bytes into an instance of class <tt>Class</tt>.
-     * Before the <tt>Class</tt> can be used it must be resolved.  This method
+     * Finds the class with the given <a href="#binary-name">binary name</a>
+     * in a module defined to this class loader.
+     * Class loader implementations that support loading from modules
+     * should override this method.
+     *
+     * @apiNote This method returns {@code null} rather than throwing
+     *          {@code ClassNotFoundException} if the class could not be found.
+     *
+     * @implSpec The default implementation attempts to find the class by
+     * invoking {@link #findClass(String)} when the {@code moduleName} is
+     * {@code null}. It otherwise returns {@code null}.
+     *
+     * @param  moduleName
+     *         The module name; or {@code null} to find the class in the
+     *         {@linkplain #getUnnamedModule() unnamed module} for this
+     *         class loader
+
+     * @param  name
+     *         The <a href="#binary-name">binary name</a> of the class
+     *
+     * @return The resulting {@code Class} object, or {@code null}
+     *         if the class could not be found.
+     *
+     * @since 9
+     * @spec JPMS
+     */
+    protected Class<?> findClass(String moduleName, String name) {
+        if (moduleName == null) {
+            try {
+                return findClass(name);
+            } catch (ClassNotFoundException ignore) { }
+        }
+        return null;
+    }
+
+
+    /**
+     * Converts an array of bytes into an instance of class {@code Class}.
+     * Before the {@code Class} can be used it must be resolved.  This method
      * is deprecated in favor of the version that takes a <a
-     * href="#name">binary name</a> as its first argument, and is more secure.
+     * href="#binary-name">binary name</a> as its first argument, and is more secure.
      *
      * @param  b
      *         The bytes that make up the class data.  The bytes in positions
-     *         <tt>off</tt> through <tt>off+len-1</tt> should have the format
+     *         {@code off} through {@code off+len-1} should have the format
      *         of a valid class file as defined by
      *         <cite>The Java&trade; Virtual Machine Specification</cite>.
      *
      * @param  off
-     *         The start offset in <tt>b</tt> of the class data
+     *         The start offset in {@code b} of the class data
      *
      * @param  len
      *         The length of the class data
      *
-     * @return  The <tt>Class</tt> object that was created from the specified
+     * @return  The {@code Class} object that was created from the specified
      *          class data
      *
      * @throws  ClassFormatError
      *          If the data did not contain a valid class
      *
      * @throws  IndexOutOfBoundsException
-     *          If either <tt>off</tt> or <tt>len</tt> is negative, or if
-     *          <tt>off+len</tt> is greater than <tt>b.length</tt>.
+     *          If either {@code off} or {@code len} is negative, or if
+     *          {@code off+len} is greater than {@code b.length}.
      *
      * @throws  SecurityException
      *          If an attempt is made to add this class to a package that
      *          contains classes that were signed by a different set of
      *          certificates than this class, or if an attempt is made
      *          to define a class in a package with a fully-qualified name
      *          that starts with "{@code java.}".
      *
      * @see  #loadClass(String, boolean)
      * @see  #resolveClass(Class)
      *
      * @deprecated  Replaced by {@link #defineClass(String, byte[], int, int)
      * defineClass(String, byte[], int, int)}
      */
-    @Deprecated
+    @Deprecated(since="1.1")
     protected final Class<?> defineClass(byte[] b, int off, int len)
         throws ClassFormatError
     {
         return defineClass(null, b, off, len, null);
     }
 
     /**
-     * Converts an array of bytes into an instance of class <tt>Class</tt>.
-     * Before the <tt>Class</tt> can be used it must be resolved.
+     * Converts an array of bytes into an instance of class {@code Class}.
+     * Before the {@code Class} can be used it must be resolved.
      *
      * <p> This method assigns a default {@link java.security.ProtectionDomain
-     * <tt>ProtectionDomain</tt>} to the newly defined class.  The
-     * <tt>ProtectionDomain</tt> is effectively granted the same set of
+     * ProtectionDomain} to the newly defined class.  The
+     * {@code ProtectionDomain} is effectively granted the same set of
      * permissions returned when {@link
      * java.security.Policy#getPermissions(java.security.CodeSource)
-     * <tt>Policy.getPolicy().getPermissions(new CodeSource(null, null))</tt>}
-     * is invoked.  The default domain is created on the first invocation of
-     * {@link #defineClass(String, byte[], int, int) <tt>defineClass</tt>},
+     * Policy.getPolicy().getPermissions(new CodeSource(null, null))}
+     * is invoked.  The default protection domain is created on the first invocation
+     * of {@link #defineClass(String, byte[], int, int) defineClass},
      * and re-used on subsequent invocations.
      *
-     * <p> To assign a specific <tt>ProtectionDomain</tt> to the class, use
+     * <p> To assign a specific {@code ProtectionDomain} to the class, use
      * the {@link #defineClass(String, byte[], int, int,
-     * java.security.ProtectionDomain) <tt>defineClass</tt>} method that takes a
-     * <tt>ProtectionDomain</tt> as one of its arguments.  </p>
+     * java.security.ProtectionDomain) defineClass} method that takes a
+     * {@code ProtectionDomain} as one of its arguments.  </p>
+     *
+     * <p>
+     * This method defines a package in this class loader corresponding to the
+     * package of the {@code Class} (if such a package has not already been defined
+     * in this class loader). The name of the defined package is derived from
+     * the <a href="#binary-name">binary name</a> of the class specified by
+     * the byte array {@code b}.
+     * Other properties of the defined package are as specified by {@link Package}.
      *
      * @param  name
-     *         The expected <a href="#name">binary name</a> of the class, or
-     *         <tt>null</tt> if not known
+     *         The expected <a href="#binary-name">binary name</a> of the class, or
+     *         {@code null} if not known
      *
      * @param  b
      *         The bytes that make up the class data.  The bytes in positions
-     *         <tt>off</tt> through <tt>off+len-1</tt> should have the format
+     *         {@code off} through {@code off+len-1} should have the format
      *         of a valid class file as defined by
      *         <cite>The Java&trade; Virtual Machine Specification</cite>.
      *
      * @param  off
-     *         The start offset in <tt>b</tt> of the class data
+     *         The start offset in {@code b} of the class data
      *
      * @param  len
      *         The length of the class data
      *
-     * @return  The <tt>Class</tt> object that was created from the specified
+     * @return  The {@code Class} object that was created from the specified
      *          class data.
      *
      * @throws  ClassFormatError
      *          If the data did not contain a valid class
      *
      * @throws  IndexOutOfBoundsException
-     *          If either <tt>off</tt> or <tt>len</tt> is negative, or if
-     *          <tt>off+len</tt> is greater than <tt>b.length</tt>.
+     *          If either {@code off} or {@code len} is negative, or if
+     *          {@code off+len} is greater than {@code b.length}.
      *
      * @throws  SecurityException
      *          If an attempt is made to add this class to a package that
      *          contains classes that were signed by a different set of
      *          certificates than this class (which is unsigned), or if
-     *          <tt>name</tt> begins with "<tt>java.</tt>".
+     *          {@code name} begins with "{@code java.}".
      *
      * @see  #loadClass(String, boolean)
      * @see  #resolveClass(Class)
      * @see  java.security.CodeSource
      * @see  java.security.SecureClassLoader
      *
      * @since  1.1
+     * @revised 9
+     * @spec JPMS
      */
     protected final Class<?> defineClass(String name, byte[] b, int off, int len)
         throws ClassFormatError
     {
         return defineClass(name, b, off, len, null);
     }
 
     /* Determine protection domain, and check that:
         - not define java.* class,
         - signer of this class matches signers for the rest of the classes in
           package.
     */
     private ProtectionDomain preDefineClass(String name,
                                             ProtectionDomain pd)
     {
         if (!checkName(name))
             throw new NoClassDefFoundError("IllegalName: " + name);
 
         // Note:  Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
         // relies on the fact that spoofing is impossible if a class has a name
         // of the form "java.*"
-        if ((name != null) && name.startsWith("java.")) {
+        if ((name != null) && name.startsWith("java.")
+                && this != getBuiltinPlatformClassLoader()) {
             throw new SecurityException
                 ("Prohibited package name: " +
                  name.substring(0, name.lastIndexOf('.')));
         }
         if (pd == null) {
             pd = defaultDomain;
         }
 
-        if (name != null) checkCerts(name, pd.getCodeSource());
+        if (name != null) {
+            checkCerts(name, pd.getCodeSource());
+        }
 
         return pd;
     }
 
-    private String defineClassSourceLocation(ProtectionDomain pd)
-    {
+    private String defineClassSourceLocation(ProtectionDomain pd) {
         CodeSource cs = pd.getCodeSource();
         String source = null;
         if (cs != null && cs.getLocation() != null) {
             source = cs.getLocation().toString();
         }
         return source;
     }
 
-    private void postDefineClass(Class<?> c, ProtectionDomain pd)
-    {
+    private void postDefineClass(Class<?> c, ProtectionDomain pd) {
+        // define a named package, if not present
+        getNamedPackage(c.getPackageName(), c.getModule());
+
         if (pd.getCodeSource() != null) {
             Certificate certs[] = pd.getCodeSource().getCertificates();
             if (certs != null)
                 setSigners(c, certs);
         }
     }
 
     /**
-     * Converts an array of bytes into an instance of class <tt>Class</tt>,
-     * with an optional <tt>ProtectionDomain</tt>.  If the domain is
-     * <tt>null</tt>, then a default domain will be assigned to the class as
-     * specified in the documentation for {@link #defineClass(String, byte[],
-     * int, int)}.  Before the class can be used it must be resolved.
+     * Converts an array of bytes into an instance of class {@code Class},
+     * with a given {@code ProtectionDomain}.
+     *
+     * <p> If the given {@code ProtectionDomain} is {@code null},
+     * then a default protection domain will be assigned to the class as specified
+     * in the documentation for {@link #defineClass(String, byte[], int, int)}.
+     * Before the class can be used it must be resolved.
      *
      * <p> The first class defined in a package determines the exact set of
      * certificates that all subsequent classes defined in that package must
      * contain.  The set of certificates for a class is obtained from the
-     * {@link java.security.CodeSource <tt>CodeSource</tt>} within the
-     * <tt>ProtectionDomain</tt> of the class.  Any classes added to that
+     * {@link java.security.CodeSource CodeSource} within the
+     * {@code ProtectionDomain} of the class.  Any classes added to that
      * package must contain the same set of certificates or a
-     * <tt>SecurityException</tt> will be thrown.  Note that if
-     * <tt>name</tt> is <tt>null</tt>, this check is not performed.
-     * You should always pass in the <a href="#name">binary name</a> of the
+     * {@code SecurityException} will be thrown.  Note that if
+     * {@code name} is {@code null}, this check is not performed.
+     * You should always pass in the <a href="#binary-name">binary name</a> of the
      * class you are defining as well as the bytes.  This ensures that the
      * class you are defining is indeed the class you think it is.
      *
-     * <p> The specified <tt>name</tt> cannot begin with "<tt>java.</tt>", since
-     * all classes in the "<tt>java.*</tt> packages can only be defined by the
-     * bootstrap class loader.  If <tt>name</tt> is not <tt>null</tt>, it
-     * must be equal to the <a href="#name">binary name</a> of the class
-     * specified by the byte array "<tt>b</tt>", otherwise a {@link
-     * NoClassDefFoundError <tt>NoClassDefFoundError</tt>} will be thrown. </p>
+     * <p> If the specified {@code name} begins with "{@code java.}", it can
+     * only be defined by the {@linkplain #getPlatformClassLoader()
+     * platform class loader} or its ancestors; otherwise {@code SecurityException}
+     * will be thrown.  If {@code name} is not {@code null}, it must be equal to
+     * the <a href="#binary-name">binary name</a> of the class
+     * specified by the byte array {@code b}, otherwise a {@link
+     * NoClassDefFoundError NoClassDefFoundError} will be thrown.
+     *
+     * <p> This method defines a package in this class loader corresponding to the
+     * package of the {@code Class} (if such a package has not already been defined
+     * in this class loader). The name of the defined package is derived from
+     * the <a href="#binary-name">binary name</a> of the class specified by
+     * the byte array {@code b}.
+     * Other properties of the defined package are as specified by {@link Package}.
      *
      * @param  name
-     *         The expected <a href="#name">binary name</a> of the class, or
-     *         <tt>null</tt> if not known
+     *         The expected <a href="#binary-name">binary name</a> of the class, or
+     *         {@code null} if not known
      *
      * @param  b
      *         The bytes that make up the class data. The bytes in positions
-     *         <tt>off</tt> through <tt>off+len-1</tt> should have the format
+     *         {@code off} through {@code off+len-1} should have the format
      *         of a valid class file as defined by
      *         <cite>The Java&trade; Virtual Machine Specification</cite>.
      *
      * @param  off
-     *         The start offset in <tt>b</tt> of the class data
+     *         The start offset in {@code b} of the class data
      *
      * @param  len
      *         The length of the class data
      *
      * @param  protectionDomain
-     *         The ProtectionDomain of the class
+     *         The {@code ProtectionDomain} of the class
      *
-     * @return  The <tt>Class</tt> object created from the data,
-     *          and optional <tt>ProtectionDomain</tt>.
+     * @return  The {@code Class} object created from the data,
+     *          and {@code ProtectionDomain}.
      *
      * @throws  ClassFormatError
      *          If the data did not contain a valid class
      *
      * @throws  NoClassDefFoundError
-     *          If <tt>name</tt> is not equal to the <a href="#name">binary
-     *          name</a> of the class specified by <tt>b</tt>
+     *          If {@code name} is not {@code null} and not equal to the
+     *          <a href="#binary-name">binary name</a> of the class specified by {@code b}
      *
      * @throws  IndexOutOfBoundsException
-     *          If either <tt>off</tt> or <tt>len</tt> is negative, or if
-     *          <tt>off+len</tt> is greater than <tt>b.length</tt>.
+     *          If either {@code off} or {@code len} is negative, or if
+     *          {@code off+len} is greater than {@code b.length}.
      *
      * @throws  SecurityException
      *          If an attempt is made to add this class to a package that
      *          contains classes that were signed by a different set of
-     *          certificates than this class, or if <tt>name</tt> begins with
-     *          "<tt>java.</tt>".
+     *          certificates than this class, or if {@code name} begins with
+     *          "{@code java.}" and this class loader is not the platform
+     *          class loader or its ancestor.
+     *
+     * @revised 9
+     * @spec JPMS
      */
     protected final Class<?> defineClass(String name, byte[] b, int off, int len,
                                          ProtectionDomain protectionDomain)
         throws ClassFormatError
     {
         protectionDomain = preDefineClass(name, protectionDomain);
         String source = defineClassSourceLocation(protectionDomain);
-        Class<?> c = defineClass1(name, b, off, len, protectionDomain, source);
+        Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source);
         postDefineClass(c, protectionDomain);
         return c;
     }
 
     /**
-     * Converts a {@link java.nio.ByteBuffer <tt>ByteBuffer</tt>}
-     * into an instance of class <tt>Class</tt>,
-     * with an optional <tt>ProtectionDomain</tt>.  If the domain is
-     * <tt>null</tt>, then a default domain will be assigned to the class as
+     * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance
+     * of class {@code Class}, with the given {@code ProtectionDomain}.
+     * If the given {@code ProtectionDomain} is {@code null}, then a default
+     * protection domain will be assigned to the class as
      * specified in the documentation for {@link #defineClass(String, byte[],
      * int, int)}.  Before the class can be used it must be resolved.
      *
      * <p>The rules about the first class defined in a package determining the
-     * set of certificates for the package, and the restrictions on class names
+     * set of certificates for the package, the restrictions on class names,
+     * and the defined package of the class
      * are identical to those specified in the documentation for {@link
      * #defineClass(String, byte[], int, int, ProtectionDomain)}.
      *
      * <p> An invocation of this method of the form
-     * <i>cl</i><tt>.defineClass(</tt><i>name</i><tt>,</tt>
-     * <i>bBuffer</i><tt>,</tt> <i>pd</i><tt>)</tt> yields exactly the same
+     * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,}
+     * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same
      * result as the statements
      *
-     *<p> <tt>
+     *<p> <code>
      * ...<br>
      * byte[] temp = new byte[bBuffer.{@link
      * java.nio.ByteBuffer#remaining remaining}()];<br>
      *     bBuffer.{@link java.nio.ByteBuffer#get(byte[])
      * get}(temp);<br>
      *     return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
      * cl.defineClass}(name, temp, 0,
      * temp.length, pd);<br>
-     * </tt></p>
+     * </code></p>
      *
      * @param  name
-     *         The expected <a href="#name">binary name</a>. of the class, or
-     *         <tt>null</tt> if not known
+     *         The expected <a href="#binary-name">binary name</a>. of the class, or
+     *         {@code null} if not known
      *
      * @param  b
      *         The bytes that make up the class data. The bytes from positions
-     *         <tt>b.position()</tt> through <tt>b.position() + b.limit() -1
-     *         </tt> should have the format of a valid class file as defined by
+     *         {@code b.position()} through {@code b.position() + b.limit() -1
+     *         } should have the format of a valid class file as defined by
      *         <cite>The Java&trade; Virtual Machine Specification</cite>.
      *
      * @param  protectionDomain
-     *         The ProtectionDomain of the class, or <tt>null</tt>.
+     *         The {@code ProtectionDomain} of the class, or {@code null}.
      *
-     * @return  The <tt>Class</tt> object created from the data,
-     *          and optional <tt>ProtectionDomain</tt>.
+     * @return  The {@code Class} object created from the data,
+     *          and {@code ProtectionDomain}.
      *
      * @throws  ClassFormatError
      *          If the data did not contain a valid class.
      *
      * @throws  NoClassDefFoundError
-     *          If <tt>name</tt> is not equal to the <a href="#name">binary
-     *          name</a> of the class specified by <tt>b</tt>
+     *          If {@code name} is not {@code null} and not equal to the
+     *          <a href="#binary-name">binary name</a> of the class specified by {@code b}
      *
      * @throws  SecurityException
      *          If an attempt is made to add this class to a package that
      *          contains classes that were signed by a different set of
-     *          certificates than this class, or if <tt>name</tt> begins with
-     *          "<tt>java.</tt>".
+     *          certificates than this class, or if {@code name} begins with
+     *          "{@code java.}".
      *
      * @see      #defineClass(String, byte[], int, int, ProtectionDomain)
      *
      * @since  1.5
+     * @revised 9
+     * @spec JPMS
      */
     protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
                                          ProtectionDomain protectionDomain)
         throws ClassFormatError
     {
         int len = b.remaining();
 
-        // Use byte[] if not a direct ByteBufer:
+        // Use byte[] if not a direct ByteBuffer:
         if (!b.isDirect()) {
             if (b.hasArray()) {
                 return defineClass(name, b.array(),
                                    b.position() + b.arrayOffset(), len,
                                    protectionDomain);
             } else {
                 // no array, or read-only array
                 byte[] tb = new byte[len];
                 b.get(tb);  // get bytes out of byte buffer.
                 return defineClass(name, tb, 0, len, protectionDomain);
             }
         }
 
         protectionDomain = preDefineClass(name, protectionDomain);
         String source = defineClassSourceLocation(protectionDomain);
-        Class<?> c = defineClass2(name, b, b.position(), len, protectionDomain, source);
+        Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source);
         postDefineClass(c, protectionDomain);
         return c;
     }
 
-    private native Class<?> defineClass0(String name, byte[] b, int off, int len,
-                                         ProtectionDomain pd);
+    static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len,
+                                        ProtectionDomain pd, String source);
 
-    private native Class<?> defineClass1(String name, byte[] b, int off, int len,
-                                         ProtectionDomain pd, String source);
-
-    private native Class<?> defineClass2(String name, java.nio.ByteBuffer b,
-                                         int off, int len, ProtectionDomain pd,
-                                         String source);
+    static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b,
+                                        int off, int len, ProtectionDomain pd,
+                                        String source);
 
     // true if the name is null or has the potential to be a valid binary name
     private boolean checkName(String name) {
-        if ((name == null) || (name.length() == 0))
+        if ((name == null) || (name.isEmpty()))
             return true;
-        if ((name.indexOf('/') != -1)
-            || (!VM.allowArraySyntax() && (name.charAt(0) == '[')))
+        if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
             return false;
         return true;
     }
 
     private void checkCerts(String name, CodeSource cs) {
         int i = name.lastIndexOf('.');
         String pname = (i == -1) ? "" : name.substring(0, i);
 
         Certificate[] certs = null;
         if (cs != null) {
             certs = cs.getCertificates();
         }
         Certificate[] pcerts = null;
         if (parallelLockMap == null) {
             synchronized (this) {
                 pcerts = package2certs.get(pname);
                 if (pcerts == null) {
                     package2certs.put(pname, (certs == null? nocerts:certs));
                 }
             }
         } else {
             pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
                 putIfAbsent(pname, (certs == null? nocerts:certs));
         }
         if (pcerts != null && !compareCerts(pcerts, certs)) {
-            throw new SecurityException("class \""+ name +
-                 "\"'s signer information does not match signer information of other classes in the same package");
+            throw new SecurityException("class \"" + name
+                + "\"'s signer information does not match signer information"
+                + " of other classes in the same package");
         }
     }
 
     /**
      * check to make sure the certs for the new class (certs) are the same as
      * the certs for the first class inserted in the package (pcerts)
      */
     private boolean compareCerts(Certificate[] pcerts,
                                  Certificate[] certs)
     {
         // certs can be null, indicating no certs.
         if ((certs == null) || (certs.length == 0)) {
             return pcerts.length == 0;
         }
 
         // the length must be the same at this point
         if (certs.length != pcerts.length)
             return false;
 
         // go through and make sure all the certs in one array
         // are in the other and vice-versa.
         boolean match;
-        for (int i = 0; i < certs.length; i++) {
+        for (Certificate cert : certs) {
             match = false;
-            for (int j = 0; j < pcerts.length; j++) {
-                if (certs[i].equals(pcerts[j])) {
+            for (Certificate pcert : pcerts) {
+                if (cert.equals(pcert)) {
                     match = true;
                     break;
                 }
             }
             if (!match) return false;
         }
 
         // now do the same for pcerts
-        for (int i = 0; i < pcerts.length; i++) {
+        for (Certificate pcert : pcerts) {
             match = false;
-            for (int j = 0; j < certs.length; j++) {
-                if (pcerts[i].equals(certs[j])) {
+            for (Certificate cert : certs) {
+                if (pcert.equals(cert)) {
                     match = true;
                     break;
                 }
             }
             if (!match) return false;
         }
 
         return true;
     }
 
     /**
      * Links the specified class.  This (misleadingly named) method may be
-     * used by a class loader to link a class.  If the class <tt>c</tt> has
+     * used by a class loader to link a class.  If the class {@code c} has
      * already been linked, then this method simply returns. Otherwise, the
      * class is linked as described in the "Execution" chapter of
      * <cite>The Java&trade; Language Specification</cite>.
      *
      * @param  c
      *         The class to link
      *
      * @throws  NullPointerException
-     *          If <tt>c</tt> is <tt>null</tt>.
+     *          If {@code c} is {@code null}.
      *
      * @see  #defineClass(String, byte[], int, int)
      */
     protected final void resolveClass(Class<?> c) {
-        resolveClass0(c);
+        if (c == null) {
+            throw new NullPointerException();
+        }
     }
 
-    private native void resolveClass0(Class<?> c);
-
     /**
-     * Finds a class with the specified <a href="#name">binary name</a>,
+     * Finds a class with the specified <a href="#binary-name">binary name</a>,
      * loading it if necessary.
      *
      * <p> This method loads the class through the system class loader (see
-     * {@link #getSystemClassLoader()}).  The <tt>Class</tt> object returned
-     * might have more than one <tt>ClassLoader</tt> associated with it.
-     * Subclasses of <tt>ClassLoader</tt> need not usually invoke this method,
+     * {@link #getSystemClassLoader()}).  The {@code Class} object returned
+     * might have more than one {@code ClassLoader} associated with it.
+     * Subclasses of {@code ClassLoader} need not usually invoke this method,
      * because most class loaders need to override just {@link
      * #findClass(String)}.  </p>
      *
      * @param  name
-     *         The <a href="#name">binary name</a> of the class
+     *         The <a href="#binary-name">binary name</a> of the class
      *
-     * @return  The <tt>Class</tt> object for the specified <tt>name</tt>
+     * @return  The {@code Class} object for the specified {@code name}
      *
      * @throws  ClassNotFoundException
      *          If the class could not be found
      *
      * @see  #ClassLoader(ClassLoader)
      * @see  #getParent()
      */
     protected final Class<?> findSystemClass(String name)
         throws ClassNotFoundException
     {
-        ClassLoader system = getSystemClassLoader();
-        if (system == null) {
-            if (!checkName(name))
-                throw new ClassNotFoundException(name);
-            Class<?> cls = findBootstrapClass(name);
-            if (cls == null) {
-                throw new ClassNotFoundException(name);
-            }
-            return cls;
-        }
-        return system.loadClass(name);
+        return getSystemClassLoader().loadClass(name);
     }
 
     /**
      * Returns a class loaded by the bootstrap class loader;
      * or return null if not found.
      */
-    private Class<?> findBootstrapClassOrNull(String name)
-    {
+    Class<?> findBootstrapClassOrNull(String name) {
         if (!checkName(name)) return null;
 
         return findBootstrapClass(name);
     }
 
     // return null if not found
     private native Class<?> findBootstrapClass(String name);
 
     /**
-     * Returns the class with the given <a href="#name">binary name</a> if this
+     * Returns the class with the given <a href="#binary-name">binary name</a> if this
      * loader has been recorded by the Java virtual machine as an initiating
-     * loader of a class with that <a href="#name">binary name</a>.  Otherwise
-     * <tt>null</tt> is returned.
+     * loader of a class with that <a href="#binary-name">binary name</a>.  Otherwise
+     * {@code null} is returned.
      *
      * @param  name
-     *         The <a href="#name">binary name</a> of the class
+     *         The <a href="#binary-name">binary name</a> of the class
      *
-     * @return  The <tt>Class</tt> object, or <tt>null</tt> if the class has
+     * @return  The {@code Class} object, or {@code null} if the class has
      *          not been loaded
      *
      * @since  1.1
      */
     protected final Class<?> findLoadedClass(String name) {
         if (!checkName(name))
             return null;
         return findLoadedClass0(name);
     }
 
-    private native final Class<?> findLoadedClass0(String name);
+    private final native Class<?> findLoadedClass0(String name);
 
     /**
      * Sets the signers of a class.  This should be invoked after defining a
      * class.
      *
      * @param  c
-     *         The <tt>Class</tt> object
+     *         The {@code Class} object
      *
      * @param  signers
      *         The signers for the class
      *
      * @since  1.1
      */
     protected final void setSigners(Class<?> c, Object[] signers) {
         c.setSigners(signers);
     }
 
 
-    // -- Resource --
+    // -- Resources --
+
+    /**
+     * Returns a URL to a resource in a module defined to this class loader.
+     * Class loader implementations that support loading from modules
+     * should override this method.
+     *
+     * @apiNote This method is the basis for the {@link
+     * Class#getResource Class.getResource}, {@link Class#getResourceAsStream
+     * Class.getResourceAsStream}, and {@link Module#getResourceAsStream
+     * Module.getResourceAsStream} methods. It is not subject to the rules for
+     * encapsulation specified by {@code Module.getResourceAsStream}.
+     *
+     * @implSpec The default implementation attempts to find the resource by
+     * invoking {@link #findResource(String)} when the {@code moduleName} is
+     * {@code null}. It otherwise returns {@code null}.
+     *
+     * @param  moduleName
+     *         The module name; or {@code null} to find a resource in the
+     *         {@linkplain #getUnnamedModule() unnamed module} for this
+     *         class loader
+     * @param  name
+     *         The resource name
+     *
+     * @return A URL to the resource; {@code null} if the resource could not be
+     *         found, a URL could not be constructed to locate the resource,
+     *         access to the resource is denied by the security manager, or
+     *         there isn't a module of the given name defined to the class
+     *         loader.
+     *
+     * @throws IOException
+     *         If I/O errors occur
+     *
+     * @see java.lang.module.ModuleReader#find(String)
+     * @since 9
+     * @spec JPMS
+     */
+    protected URL findResource(String moduleName, String name) throws IOException {
+        if (moduleName == null) {
+            return findResource(name);
+        } else {
+            return null;
+        }
+    }
 
     /**
      * Finds the resource with the given name.  A resource is some data
      * (images, audio, text, etc) that can be accessed by class code in a way
      * that is independent of the location of the code.
      *
-     * <p> The name of a resource is a '<tt>/</tt>'-separated path name that
-     * identifies the resource.
+     * <p> The name of a resource is a '{@code /}'-separated path name that
+     * identifies the resource. </p>
      *
-     * <p> This method will first search the parent class loader for the
-     * resource; if the parent is <tt>null</tt> the path of the class loader
-     * built-in to the virtual machine is searched.  That failing, this method
-     * will invoke {@link #findResource(String)} to find the resource.  </p>
+     * <p> Resources in named modules are subject to the encapsulation rules
+     * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+     * Additionally, and except for the special case where the resource has a
+     * name ending with "{@code .class}", this method will only find resources in
+     * packages of named modules when the package is {@link Module#isOpen(String)
+     * opened} unconditionally (even if the caller of this method is in the
+     * same module as the resource). </p>
      *
-     * @apiNote When overriding this method it is recommended that an
-     * implementation ensures that any delegation is consistent with the {@link
+     * @implSpec The default implementation will first search the parent class
+     * loader for the resource; if the parent is {@code null} the path of the
+     * class loader built into the virtual machine is searched. If not found,
+     * this method will invoke {@link #findResource(String)} to find the resource.
+     *
+     * @apiNote Where several modules are defined to the same class loader,
+     * and where more than one module contains a resource with the given name,
+     * then the ordering that modules are searched is not specified and may be
+     * very unpredictable.
+     * When overriding this method it is recommended that an implementation
+     * ensures that any delegation is consistent with the {@link
      * #getResources(java.lang.String) getResources(String)} method.
      *
      * @param  name
      *         The resource name
      *
-     * @return  A <tt>URL</tt> object for reading the resource, or
-     *          <tt>null</tt> if the resource could not be found or the invoker
-     *          doesn't have adequate  privileges to get the resource.
+     * @return  {@code URL} object for reading the resource; {@code null} if
+     *          the resource could not be found, a {@code URL} could not be
+     *          constructed to locate the resource, the resource is in a package
+     *          that is not opened unconditionally, or access to the resource is
+     *          denied by the security manager.
+     *
+     * @throws  NullPointerException If {@code name} is {@code null}
      *
      * @since  1.1
+     * @revised 9
+     * @spec JPMS
      */
     public URL getResource(String name) {
+        Objects.requireNonNull(name);
         URL url;
         if (parent != null) {
             url = parent.getResource(name);
         } else {
-            url = getBootstrapResource(name);
+            url = BootLoader.findResource(name);
         }
         if (url == null) {
             url = findResource(name);
         }
         return url;
     }
 
     /**
      * Finds all the resources with the given name. A resource is some data
      * (images, audio, text, etc) that can be accessed by class code in a way
      * that is independent of the location of the code.
      *
-     * <p>The name of a resource is a <tt>/</tt>-separated path name that
-     * identifies the resource.
+     * <p> The name of a resource is a {@code /}-separated path name that
+     * identifies the resource. </p>
      *
-     * <p> The search order is described in the documentation for {@link
-     * #getResource(String)}.  </p>
+     * <p> Resources in named modules are subject to the encapsulation rules
+     * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+     * Additionally, and except for the special case where the resource has a
+     * name ending with "{@code .class}", this method will only find resources in
+     * packages of named modules when the package is {@link Module#isOpen(String)
+     * opened} unconditionally (even if the caller of this method is in the
+     * same module as the resource). </p>
      *
-     * @apiNote When overriding this method it is recommended that an
+     * @implSpec The default implementation will first search the parent class
+     * loader for the resource; if the parent is {@code null} the path of the
+     * class loader built into the virtual machine is searched. It then
+     * invokes {@link #findResources(String)} to find the resources with the
+     * name in this class loader. It returns an enumeration whose elements
+     * are the URLs found by searching the parent class loader followed by
+     * the elements found with {@code findResources}.
+     *
+     * @apiNote Where several modules are defined to the same class loader,
+     * and where more than one module contains a resource with the given name,
+     * then the ordering is not specified and may be very unpredictable.
+     * When overriding this method it is recommended that an
      * implementation ensures that any delegation is consistent with the {@link
      * #getResource(java.lang.String) getResource(String)} method. This should
      * ensure that the first element returned by the Enumeration's
      * {@code nextElement} method is the same resource that the
      * {@code getResource(String)} method would return.
      *
      * @param  name
      *         The resource name
      *
-     * @return  An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
-     *          the resource.  If no resources could  be found, the enumeration
-     *          will be empty.  Resources that the class loader doesn't have
-     *          access to will not be in the enumeration.
+     * @return  An enumeration of {@link java.net.URL URL} objects for the
+     *          resource. If no resources could be found, the enumeration will
+     *          be empty. Resources for which a {@code URL} cannot be
+     *          constructed, are in a package that is not opened
+     *          unconditionally, or access to the resource is denied by the
+     *          security manager, are not returned in the enumeration.
      *
      * @throws  IOException
      *          If I/O errors occur
-     *
-     * @see  #findResources(String)
+     * @throws  NullPointerException If {@code name} is {@code null}
      *
      * @since  1.2
+     * @revised 9
+     * @spec JPMS
      */
     public Enumeration<URL> getResources(String name) throws IOException {
+        Objects.requireNonNull(name);
         @SuppressWarnings("unchecked")
         Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
         if (parent != null) {
             tmp[0] = parent.getResources(name);
         } else {
-            tmp[0] = getBootstrapResources(name);
+            tmp[0] = BootLoader.findResources(name);
         }
         tmp[1] = findResources(name);
 
         return new CompoundEnumeration<>(tmp);
     }
 
     /**
-     * Finds the resource with the given name. Class loader implementations
-     * should override this method to specify where to find resources.
+     * Returns a stream whose elements are the URLs of all the resources with
+     * the given name. A resource is some data (images, audio, text, etc) that
+     * can be accessed by class code in a way that is independent of the
+     * location of the code.
+     *
+     * <p> The name of a resource is a {@code /}-separated path name that
+     * identifies the resource.
+     *
+     * <p> The resources will be located when the returned stream is evaluated.
+     * If the evaluation results in an {@code IOException} then the I/O
+     * exception is wrapped in an {@link UncheckedIOException} that is then
+     * thrown.
+     *
+     * <p> Resources in named modules are subject to the encapsulation rules
+     * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+     * Additionally, and except for the special case where the resource has a
+     * name ending with "{@code .class}", this method will only find resources in
+     * packages of named modules when the package is {@link Module#isOpen(String)
+     * opened} unconditionally (even if the caller of this method is in the
+     * same module as the resource). </p>
+     *
+     * @implSpec The default implementation invokes {@link #getResources(String)
+     * getResources} to find all the resources with the given name and returns
+     * a stream with the elements in the enumeration as the source.
+     *
+     * @apiNote When overriding this method it is recommended that an
+     * implementation ensures that any delegation is consistent with the {@link
+     * #getResource(java.lang.String) getResource(String)} method. This should
+     * ensure that the first element returned by the stream is the same
+     * resource that the {@code getResource(String)} method would return.
      *
      * @param  name
      *         The resource name
      *
-     * @return  A <tt>URL</tt> object for reading the resource, or
-     *          <tt>null</tt> if the resource could not be found
+     * @return  A stream of resource {@link java.net.URL URL} objects. If no
+     *          resources could  be found, the stream will be empty. Resources
+     *          for which a {@code URL} cannot be constructed, are in a package
+     *          that is not opened unconditionally, or access to the resource
+     *          is denied by the security manager, will not be in the stream.
+     *
+     * @throws  NullPointerException If {@code name} is {@code null}
+     *
+     * @since  9
+     */
+    public Stream<URL> resources(String name) {
+        Objects.requireNonNull(name);
+        int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
+        Supplier<Spliterator<URL>> si = () -> {
+            try {
+                return Spliterators.spliteratorUnknownSize(
+                    getResources(name).asIterator(), characteristics);
+            } catch (IOException e) {
+                throw new UncheckedIOException(e);
+            }
+        };
+        return StreamSupport.stream(si, characteristics, false);
+    }
+
+    /**
+     * Finds the resource with the given name. Class loader implementations
+     * should override this method.
+     *
+     * <p> For resources in named modules then the method must implement the
+     * rules for encapsulation specified in the {@code Module} {@link
+     * Module#getResourceAsStream getResourceAsStream} method. Additionally,
+     * it must not find non-"{@code .class}" resources in packages of named
+     * modules unless the package is {@link Module#isOpen(String) opened}
+     * unconditionally. </p>
+     *
+     * @implSpec The default implementation returns {@code null}.
+     *
+     * @param  name
+     *         The resource name
+     *
+     * @return  {@code URL} object for reading the resource; {@code null} if
+     *          the resource could not be found, a {@code URL} could not be
+     *          constructed to locate the resource, the resource is in a package
+     *          that is not opened unconditionally, or access to the resource is
+     *          denied by the security manager.
      *
      * @since  1.2
+     * @revised 9
+     * @spec JPMS
      */
     protected URL findResource(String name) {
         return null;
     }
 
     /**
-     * Returns an enumeration of {@link java.net.URL <tt>URL</tt>} objects
+     * Returns an enumeration of {@link java.net.URL URL} objects
      * representing all the resources with the given name. Class loader
-     * implementations should override this method to specify where to load
-     * resources from.
+     * implementations should override this method.
+     *
+     * <p> For resources in named modules then the method must implement the
+     * rules for encapsulation specified in the {@code Module} {@link
+     * Module#getResourceAsStream getResourceAsStream} method. Additionally,
+     * it must not find non-"{@code .class}" resources in packages of named
+     * modules unless the package is {@link Module#isOpen(String) opened}
+     * unconditionally. </p>
+     *
+     * @implSpec The default implementation returns an enumeration that
+     * contains no elements.
      *
      * @param  name
      *         The resource name
      *
-     * @return  An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
-     *          the resources
+     * @return  An enumeration of {@link java.net.URL URL} objects for
+     *          the resource. If no resources could  be found, the enumeration
+     *          will be empty. Resources for which a {@code URL} cannot be
+     *          constructed, are in a package that is not opened unconditionally,
+     *          or access to the resource is denied by the security manager,
+     *          are not returned in the enumeration.
      *
      * @throws  IOException
      *          If I/O errors occur
      *
      * @since  1.2
+     * @revised 9
+     * @spec JPMS
      */
     protected Enumeration<URL> findResources(String name) throws IOException {
-        return java.util.Collections.emptyEnumeration();
+        return Collections.emptyEnumeration();
     }
 
     /**
-     * Registers the caller as parallel capable.
+     * Registers the caller as
+     * {@linkplain #isRegisteredAsParallelCapable() parallel capable}.
      * The registration succeeds if and only if all of the following
      * conditions are met:
      * <ol>
      * <li> no instance of the caller has been created</li>
      * <li> all of the super classes (except class Object) of the caller are
      * registered as parallel capable</li>
      * </ol>
      * <p>Note that once a class loader is registered as parallel capable, there
      * is no way to change it back.</p>
      *
-     * @return  true if the caller is successfully registered as
-     *          parallel capable and false if otherwise.
+     * @return  {@code true} if the caller is successfully registered as
+     *          parallel capable and {@code false} if otherwise.
+     *
+     * @see #isRegisteredAsParallelCapable()
      *
      * @since   1.7
      */
     @CallerSensitive
     protected static boolean registerAsParallelCapable() {
         Class<? extends ClassLoader> callerClass =
             Reflection.getCallerClass().asSubclass(ClassLoader.class);
         return ParallelLoaders.register(callerClass);
     }
 
     /**
+     * Returns {@code true} if this class loader is registered as
+     * {@linkplain #registerAsParallelCapable parallel capable}, otherwise
+     * {@code false}.
+     *
+     * @return  {@code true} if this class loader is parallel capable,
+     *          otherwise {@code false}.
+     *
+     * @see #registerAsParallelCapable()
+     *
+     * @since   9
+     */
+    public final boolean isRegisteredAsParallelCapable() {
+        return ParallelLoaders.isRegistered(this.getClass());
+    }
+
+    /**
      * Find a resource of the specified name from the search path used to load
      * classes.  This method locates the resource through the system class
      * loader (see {@link #getSystemClassLoader()}).
      *
+     * <p> Resources in named modules are subject to the encapsulation rules
+     * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+     * Additionally, and except for the special case where the resource has a
+     * name ending with "{@code .class}", this method will only find resources in
+     * packages of named modules when the package is {@link Module#isOpen(String)
+     * opened} unconditionally. </p>
+     *
      * @param  name
      *         The resource name
      *
-     * @return  A {@link java.net.URL <tt>URL</tt>} object for reading the
-     *          resource, or <tt>null</tt> if the resource could not be found
+     * @return  A {@link java.net.URL URL} to the resource; {@code
+     *          null} if the resource could not be found, a URL could not be
+     *          constructed to locate the resource, the resource is in a package
+     *          that is not opened unconditionally or access to the resource is
+     *          denied by the security manager.
      *
      * @since  1.1
+     * @revised 9
+     * @spec JPMS
      */
     public static URL getSystemResource(String name) {
-        ClassLoader system = getSystemClassLoader();
-        if (system == null) {
-            return getBootstrapResource(name);
-        }
-        return system.getResource(name);
+        return getSystemClassLoader().getResource(name);
     }
 
     /**
      * Finds all resources of the specified name from the search path used to
      * load classes.  The resources thus found are returned as an
-     * {@link java.util.Enumeration <tt>Enumeration</tt>} of {@link
-     * java.net.URL <tt>URL</tt>} objects.
+     * {@link java.util.Enumeration Enumeration} of {@link
+     * java.net.URL URL} objects.
      *
      * <p> The search order is described in the documentation for {@link
      * #getSystemResource(String)}.  </p>
      *
+     * <p> Resources in named modules are subject to the encapsulation rules
+     * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+     * Additionally, and except for the special case where the resource has a
+     * name ending with "{@code .class}", this method will only find resources in
+     * packages of named modules when the package is {@link Module#isOpen(String)
+     * opened} unconditionally. </p>
+     *
      * @param  name
      *         The resource name
      *
-     * @return  An enumeration of resource {@link java.net.URL <tt>URL</tt>}
-     *          objects
+     * @return  An enumeration of {@link java.net.URL URL} objects for
+     *          the resource. If no resources could  be found, the enumeration
+     *          will be empty. Resources for which a {@code URL} cannot be
+     *          constructed, are in a package that is not opened unconditionally,
+     *          or access to the resource is denied by the security manager,
+     *          are not returned in the enumeration.
      *
      * @throws  IOException
      *          If I/O errors occur
-
+     *
      * @since  1.2
+     * @revised 9
+     * @spec JPMS
      */
     public static Enumeration<URL> getSystemResources(String name)
         throws IOException
     {
-        ClassLoader system = getSystemClassLoader();
-        if (system == null) {
-            return getBootstrapResources(name);
-        }
-        return system.getResources(name);
+        return getSystemClassLoader().getResources(name);
     }
 
     /**
-     * Find resources from the VM's built-in classloader.
-     */
-    private static URL getBootstrapResource(String name) {
-        URLClassPath ucp = getBootstrapClassPath();
-        Resource res = ucp.getResource(name);
-        return res != null ? res.getURL() : null;
-    }
-
-    /**
-     * Find resources from the VM's built-in classloader.
-     */
-    private static Enumeration<URL> getBootstrapResources(String name)
-        throws IOException
-    {
-        final Enumeration<Resource> e =
-            getBootstrapClassPath().getResources(name);
-        return new Enumeration<URL> () {
-            public URL nextElement() {
-                return e.nextElement().getURL();
-            }
-            public boolean hasMoreElements() {
-                return e.hasMoreElements();
-            }
-        };
-    }
-
-    // Returns the URLClassPath that is used for finding system resources.
-    static URLClassPath getBootstrapClassPath() {
-        return sun.misc.Launcher.getBootstrapClassPath();
-    }
-
-
-    /**
      * Returns an input stream for reading the specified resource.
      *
      * <p> The search order is described in the documentation for {@link
      * #getResource(String)}.  </p>
      *
+     * <p> Resources in named modules are subject to the encapsulation rules
+     * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+     * Additionally, and except for the special case where the resource has a
+     * name ending with "{@code .class}", this method will only find resources in
+     * packages of named modules when the package is {@link Module#isOpen(String)
+     * opened} unconditionally. </p>
+     *
      * @param  name
      *         The resource name
      *
-     * @return  An input stream for reading the resource, or <tt>null</tt>
-     *          if the resource could not be found
+     * @return  An input stream for reading the resource; {@code null} if the
+     *          resource could not be found, the resource is in a package that
+     *          is not opened unconditionally, or access to the resource is
+     *          denied by the security manager.
+     *
+     * @throws  NullPointerException If {@code name} is {@code null}
      *
      * @since  1.1
+     * @revised 9
+     * @spec JPMS
      */
     public InputStream getResourceAsStream(String name) {
+        Objects.requireNonNull(name);
         URL url = getResource(name);
         try {
             return url != null ? url.openStream() : null;
         } catch (IOException e) {
             return null;
         }
     }
 
     /**
      * Open for reading, a resource of the specified name from the search path
      * used to load classes.  This method locates the resource through the
      * system class loader (see {@link #getSystemClassLoader()}).
      *
+     * <p> Resources in named modules are subject to the encapsulation rules
+     * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+     * Additionally, and except for the special case where the resource has a
+     * name ending with "{@code .class}", this method will only find resources in
+     * packages of named modules when the package is {@link Module#isOpen(String)
+     * opened} unconditionally. </p>
+     *
      * @param  name
      *         The resource name
      *
-     * @return  An input stream for reading the resource, or <tt>null</tt>
-     *          if the resource could not be found
+     * @return  An input stream for reading the resource; {@code null} if the
+     *          resource could not be found, the resource is in a package that
+     *          is not opened unconditionally, or access to the resource is
+     *          denied by the security manager.
      *
      * @since  1.1
+     * @revised 9
+     * @spec JPMS
      */
     public static InputStream getSystemResourceAsStream(String name) {
         URL url = getSystemResource(name);
         try {
             return url != null ? url.openStream() : null;
         } catch (IOException e) {
             return null;
         }
     }
 
 
     // -- Hierarchy --
 
     /**
      * Returns the parent class loader for delegation. Some implementations may
-     * use <tt>null</tt> to represent the bootstrap class loader. This method
-     * will return <tt>null</tt> in such implementations if this class loader's
+     * use {@code null} to represent the bootstrap class loader. This method
+     * will return {@code null} in such implementations if this class loader's
      * parent is the bootstrap class loader.
      *
-     * <p> If a security manager is present, and the invoker's class loader is
-     * not <tt>null</tt> and is not an ancestor of this class loader, then this
-     * method invokes the security manager's {@link
-     * SecurityManager#checkPermission(java.security.Permission)
-     * <tt>checkPermission</tt>} method with a {@link
-     * RuntimePermission#RuntimePermission(String)
-     * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
-     * access to the parent class loader is permitted.  If not, a
-     * <tt>SecurityException</tt> will be thrown.  </p>
-     *
-     * @return  The parent <tt>ClassLoader</tt>
+     * @return  The parent {@code ClassLoader}
      *
      * @throws  SecurityException
-     *          If a security manager exists and its <tt>checkPermission</tt>
-     *          method doesn't allow access to this class loader's parent class
-     *          loader.
+     *          If a security manager is present, and the caller's class loader
+     *          is not {@code null} and is not an ancestor of this class loader,
+     *          and the caller does not have the
+     *          {@link RuntimePermission}{@code ("getClassLoader")}
      *
      * @since  1.2
      */
     @CallerSensitive
     public final ClassLoader getParent() {
         if (parent == null)
             return null;
         SecurityManager sm = System.getSecurityManager();
         if (sm != null) {
             // Check access to the parent class loader
             // If the caller's class loader is same as this class loader,
             // permission check is performed.
             checkClassLoaderPermission(parent, Reflection.getCallerClass());
         }
         return parent;
     }
 
     /**
-     * Returns the system class loader for delegation.  This is the default
-     * delegation parent for new <tt>ClassLoader</tt> instances, and is
+     * Returns the unnamed {@code Module} for this class loader.
+     *
+     * @return The unnamed Module for this class loader
+     *
+     * @see Module#isNamed()
+     * @since 9
+     * @spec JPMS
+     */
+    public final Module getUnnamedModule() {
+        return unnamedModule;
+    }
+
+    /**
+     * Returns the platform class loader.  All
+     * <a href="#builtinLoaders">platform classes</a> are visible to
+     * the platform class loader.
+     *
+     * @implNote The name of the builtin platform class loader is
+     * {@code "platform"}.
+     *
+     * @return  The platform {@code ClassLoader}.
+     *
+     * @throws  SecurityException
+     *          If a security manager is present, and the caller's class loader is
+     *          not {@code null}, and the caller's class loader is not the same
+     *          as or an ancestor of the platform class loader,
+     *          and the caller does not have the
+     *          {@link RuntimePermission}{@code ("getClassLoader")}
+     *
+     * @since 9
+     * @spec JPMS
+     */
+    @CallerSensitive
+    public static ClassLoader getPlatformClassLoader() {
+        SecurityManager sm = System.getSecurityManager();
+        ClassLoader loader = getBuiltinPlatformClassLoader();
+        if (sm != null) {
+            checkClassLoaderPermission(loader, Reflection.getCallerClass());
+        }
+        return loader;
+    }
+
+    /**
+     * Returns the system class loader.  This is the default
+     * delegation parent for new {@code ClassLoader} instances, and is
      * typically the class loader used to start the application.
      *
      * <p> This method is first invoked early in the runtime's startup
-     * sequence, at which point it creates the system class loader and sets it
-     * as the context class loader of the invoking <tt>Thread</tt>.
+     * sequence, at which point it creates the system class loader. This
+     * class loader will be the context class loader for the main application
+     * thread (for example, the thread that invokes the {@code main} method of
+     * the main class).
      *
      * <p> The default system class loader is an implementation-dependent
      * instance of this class.
      *
-     * <p> If the system property "<tt>java.system.class.loader</tt>" is defined
-     * when this method is first invoked then the value of that property is
-     * taken to be the name of a class that will be returned as the system
-     * class loader.  The class is loaded using the default system class loader
-     * and must define a public constructor that takes a single parameter of
-     * type <tt>ClassLoader</tt> which is used as the delegation parent.  An
+     * <p> If the system property "{@systemProperty java.system.class.loader}"
+     * is defined when this method is first invoked then the value of that
+     * property is taken to be the name of a class that will be returned as the
+     * system class loader. The class is loaded using the default system class
+     * loader and must define a public constructor that takes a single parameter
+     * of type {@code ClassLoader} which is used as the delegation parent. An
      * instance is then created using this constructor with the default system
      * class loader as the parameter.  The resulting class loader is defined
-     * to be the system class loader.
+     * to be the system class loader. During construction, the class loader
+     * should take great care to avoid calling {@code getSystemClassLoader()}.
+     * If circular initialization of the system class loader is detected then
+     * an {@code IllegalStateException} is thrown.
      *
-     * <p> If a security manager is present, and the invoker's class loader is
-     * not <tt>null</tt> and the invoker's class loader is not the same as or
-     * an ancestor of the system class loader, then this method invokes the
-     * security manager's {@link
-     * SecurityManager#checkPermission(java.security.Permission)
-     * <tt>checkPermission</tt>} method with a {@link
-     * RuntimePermission#RuntimePermission(String)
-     * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
-     * access to the system class loader.  If not, a
-     * <tt>SecurityException</tt> will be thrown.  </p>
+     * @implNote The system property to override the system class loader is not
+     * examined until the VM is almost fully initialized. Code that executes
+     * this method during startup should take care not to cache the return
+     * value until the system is fully initialized.
      *
-     * @return  The system <tt>ClassLoader</tt> for delegation, or
-     *          <tt>null</tt> if none
+     * <p> The name of the built-in system class loader is {@code "app"}.
+     * The system property "{@code java.class.path}" is read during early
+     * initialization of the VM to determine the class path.
+     * An empty value of "{@code java.class.path}" property is interpreted
+     * differently depending on whether the initial module (the module
+     * containing the main class) is named or unnamed:
+     * If named, the built-in system class loader will have no class path and
+     * will search for classes and resources using the application module path;
+     * otherwise, if unnamed, it will set the class path to the current
+     * working directory.
+     *
+     * @return  The system {@code ClassLoader}
      *
      * @throws  SecurityException
-     *          If a security manager exists and its <tt>checkPermission</tt>
-     *          method doesn't allow access to the system class loader.
+     *          If a security manager is present, and the caller's class loader
+     *          is not {@code null} and is not the same as or an ancestor of the
+     *          system class loader, and the caller does not have the
+     *          {@link RuntimePermission}{@code ("getClassLoader")}
      *
      * @throws  IllegalStateException
      *          If invoked recursively during the construction of the class
-     *          loader specified by the "<tt>java.system.class.loader</tt>"
+     *          loader specified by the "{@code java.system.class.loader}"
      *          property.
      *
      * @throws  Error
-     *          If the system property "<tt>java.system.class.loader</tt>"
+     *          If the system property "{@code java.system.class.loader}"
      *          is defined but the named class could not be loaded, the
      *          provider class does not define the required constructor, or an
      *          exception is thrown by that constructor when it is invoked. The
      *          underlying cause of the error can be retrieved via the
      *          {@link Throwable#getCause()} method.
      *
      * @revised  1.4
+     * @revised 9
+     * @spec JPMS
      */
     @CallerSensitive
     public static ClassLoader getSystemClassLoader() {
-        initSystemClassLoader();
-        if (scl == null) {
-            return null;
+        switch (VM.initLevel()) {
+            case 0:
+            case 1:
+            case 2:
+                // the system class loader is the built-in app class loader during startup
+                return getBuiltinAppClassLoader();
+            case 3:
+                String msg = "getSystemClassLoader cannot be called during the system class loader instantiation";
+                throw new IllegalStateException(msg);
+            default:
+                // system fully initialized
+                assert VM.isBooted() && scl != null;
+                SecurityManager sm = System.getSecurityManager();
+                if (sm != null) {
+                    checkClassLoaderPermission(scl, Reflection.getCallerClass());
+                }
+                return scl;
         }
-        SecurityManager sm = System.getSecurityManager();
-        if (sm != null) {
-            checkClassLoaderPermission(scl, Reflection.getCallerClass());
-        }
-        return scl;
     }
 
-    private static synchronized void initSystemClassLoader() {
-        if (!sclSet) {
-            if (scl != null)
-                throw new IllegalStateException("recursive invocation");
-            sun.misc.Launcher l = sun.misc.Launcher.getLauncher();
-            if (l != null) {
-                Throwable oops = null;
-                scl = l.getClassLoader();
-                try {
-                    scl = AccessController.doPrivileged(
-                        new SystemClassLoaderAction(scl));
-                } catch (PrivilegedActionException pae) {
-                    oops = pae.getCause();
-                    if (oops instanceof InvocationTargetException) {
-                        oops = oops.getCause();
-                    }
-                }
-                if (oops != null) {
-                    if (oops instanceof Error) {
-                        throw (Error) oops;
-                    } else {
-                        // wrap the exception
-                        throw new Error(oops);
-                    }
-                }
-            }
-            sclSet = true;
+    static ClassLoader getBuiltinPlatformClassLoader() {
+        return ClassLoaders.platformClassLoader();
+    }
+
+    static ClassLoader getBuiltinAppClassLoader() {
+        return ClassLoaders.appClassLoader();
+    }
+
+    /*
+     * Initialize the system class loader that may be a custom class on the
+     * application class path or application module path.
+     *
+     * @see java.lang.System#initPhase3
+     */
+    static synchronized ClassLoader initSystemClassLoader() {
+        if (VM.initLevel() != 3) {
+            throw new InternalError("system class loader cannot be set at initLevel " +
+                                    VM.initLevel());
         }
+
+        // detect recursive initialization
+        if (scl != null) {
+            throw new IllegalStateException("recursive invocation");
+        }
+
+        ClassLoader builtinLoader = getBuiltinAppClassLoader();
+
+        // All are privileged frames.  No need to call doPrivileged.
+        String cn = System.getProperty("java.system.class.loader");
+        if (cn != null) {
+            try {
+                // custom class loader is only supported to be loaded from unnamed module
+                Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
+                                           .getDeclaredConstructor(ClassLoader.class);
+                scl = (ClassLoader) ctor.newInstance(builtinLoader);
+            } catch (Exception e) {
+                Throwable cause = e;
+                if (e instanceof InvocationTargetException) {
+                    cause = e.getCause();
+                    if (cause instanceof Error) {
+                        throw (Error) cause;
+                    }
+                }
+                if (cause instanceof RuntimeException) {
+                    throw (RuntimeException) cause;
+                }
+                throw new Error(cause.getMessage(), cause);
+            }
+        } else {
+            scl = builtinLoader;
+        }
+        return scl;
     }
 
     // Returns true if the specified class loader can be found in this class
     // loader's delegation chain.
     boolean isAncestor(ClassLoader cl) {
         ClassLoader acl = this;
         do {
             acl = acl.parent;
             if (cl == acl) {
                 return true;
             }
         } while (acl != null);
         return false;
     }
 
     // Tests if class loader access requires "getClassLoader" permission
     // check.  A class loader 'from' can access class loader 'to' if
     // class loader 'from' is same as class loader 'to' or an ancestor
     // of 'to'.  The class loader in a system domain can access
     // any class loader.
     private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
                                                            ClassLoader to)
     {
         if (from == to)
             return false;
 
         if (from == null)
             return false;
 
         return !to.isAncestor(from);
     }
 
     // Returns the class's class loader, or null if none.
     static ClassLoader getClassLoader(Class<?> caller) {
         // This can be null if the VM is requesting it
         if (caller == null) {
             return null;
         }
         // Circumvent security check since this is package-private
         return caller.getClassLoader0();
     }
 
     /*
      * Checks RuntimePermission("getClassLoader") permission
      * if caller's class loader is not null and caller's class loader
      * is not the same as or an ancestor of the given cl argument.
      */
     static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
         SecurityManager sm = System.getSecurityManager();
         if (sm != null) {
             // caller can be null if the VM is requesting it
             ClassLoader ccl = getClassLoader(caller);
             if (needsClassLoaderPermissionCheck(ccl, cl)) {
                 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
             }
         }
     }
 
-    // The class loader for the system
+    // The system class loader
     // @GuardedBy("ClassLoader.class")
-    private static ClassLoader scl;
-
-    // Set to true once the system class loader has been set
-    // @GuardedBy("ClassLoader.class")
-    private static boolean sclSet;
-
+    private static volatile ClassLoader scl;
 
     // -- Package --
 
     /**
-     * Defines a package by name in this <tt>ClassLoader</tt>.  This allows
-     * class loaders to define the packages for their classes. Packages must
-     * be created before the class is defined, and package names must be
-     * unique within a class loader and cannot be redefined or changed once
-     * created.
+     * Define a Package of the given Class object.
+     *
+     * If the given class represents an array type, a primitive type or void,
+     * this method returns {@code null}.
+     *
+     * This method does not throw IllegalArgumentException.
+     */
+    Package definePackage(Class<?> c) {
+        if (c.isPrimitive() || c.isArray()) {
+            return null;
+        }
+
+        return definePackage(c.getPackageName(), c.getModule());
+    }
+
+    /**
+     * Defines a Package of the given name and module
+     *
+     * This method does not throw IllegalArgumentException.
+     *
+     * @param name package name
+     * @param m    module
+     */
+    Package definePackage(String name, Module m) {
+        if (name.isEmpty() && m.isNamed()) {
+            throw new InternalError("unnamed package in  " + m);
+        }
+
+        // check if Package object is already defined
+        NamedPackage pkg = packages.get(name);
+        if (pkg instanceof Package)
+            return (Package)pkg;
+
+        return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m));
+    }
+
+    /*
+     * Returns a Package object for the named package
+     */
+    private Package toPackage(String name, NamedPackage p, Module m) {
+        // define Package object if the named package is not yet defined
+        if (p == null)
+            return NamedPackage.toPackage(name, m);
+
+        // otherwise, replace the NamedPackage object with Package object
+        if (p instanceof Package)
+            return (Package)p;
+
+        return NamedPackage.toPackage(p.packageName(), p.module());
+    }
+
+    /**
+     * Defines a package by <a href="#binary-name">name</a> in this {@code ClassLoader}.
+     * <p>
+     * <a href="#binary-name">Package names</a> must be unique within a class loader and
+     * cannot be redefined or changed once created.
+     * <p>
+     * If a class loader wishes to define a package with specific properties,
+     * such as version information, then the class loader should call this
+     * {@code definePackage} method before calling {@code defineClass}.
+     * Otherwise, the
+     * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass}
+     * method will define a package in this class loader corresponding to the package
+     * of the newly defined class; the properties of this defined package are
+     * specified by {@link Package}.
+     *
+     * @apiNote
+     * A class loader that wishes to define a package for classes in a JAR
+     * typically uses the specification and implementation titles, versions, and
+     * vendors from the JAR's manifest. If the package is specified as
+     * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest,
+     * the {@code URL} of the JAR file is typically used as the {@code sealBase}.
+     * If classes of package {@code 'p'} defined by this class loader
+     * are loaded from multiple JARs, the {@code Package} object may contain
+     * different information depending on the first class of package {@code 'p'}
+     * defined and which JAR's manifest is read first to explicitly define
+     * package {@code 'p'}.
+     *
+     * <p> It is strongly recommended that a class loader does not call this
+     * method to explicitly define packages in <em>named modules</em>; instead,
+     * the package will be automatically defined when a class is {@linkplain
+     * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}.
+     * If it is desirable to define {@code Package} explicitly, it should ensure
+     * that all packages in a named module are defined with the properties
+     * specified by {@link Package}.  Otherwise, some {@code Package} objects
+     * in a named module may be for example sealed with different seal base.
      *
      * @param  name
-     *         The package name
+     *         The <a href="#binary-name">package name</a>
      *
      * @param  specTitle
      *         The specification title
      *
      * @param  specVersion
      *         The specification version
      *
      * @param  specVendor
      *         The specification vendor
      *
      * @param  implTitle
      *         The implementation title
      *
      * @param  implVersion
      *         The implementation version
      *
      * @param  implVendor
      *         The implementation vendor
      *
      * @param  sealBase
-     *         If not <tt>null</tt>, then this package is sealed with
-     *         respect to the given code source {@link java.net.URL
-     *         <tt>URL</tt>}  object.  Otherwise, the package is not sealed.
+     *         If not {@code null}, then this package is sealed with
+     *         respect to the given code source {@link java.net.URL URL}
+     *         object.  Otherwise, the package is not sealed.
      *
-     * @return  The newly defined <tt>Package</tt> object
+     * @return  The newly defined {@code Package} object
+     *
+     * @throws  NullPointerException
+     *          if {@code name} is {@code null}.
      *
      * @throws  IllegalArgumentException
-     *          If package name duplicates an existing package either in this
-     *          class loader or one of its ancestors
+     *          if a package of the given {@code name} is already
+     *          defined by this class loader
+     *
      *
      * @since  1.2
+     * @revised 9
+     * @spec JPMS
+     *
+     * @jvms 5.3 Run-time package
+     * @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing">
+     *      The JAR File Specification: Package Sealing</a>
      */
     protected Package definePackage(String name, String specTitle,
                                     String specVersion, String specVendor,
                                     String implTitle, String implVersion,
                                     String implVendor, URL sealBase)
-        throws IllegalArgumentException
     {
-        synchronized (packages) {
-            Package pkg = getPackage(name);
-            if (pkg != null) {
-                throw new IllegalArgumentException(name);
-            }
-            pkg = new Package(name, specTitle, specVersion, specVendor,
-                              implTitle, implVersion, implVendor,
-                              sealBase, this);
-            packages.put(name, pkg);
-            return pkg;
-        }
+        Objects.requireNonNull(name);
+
+        // definePackage is not final and may be overridden by custom class loader
+        Package p = new Package(name, specTitle, specVersion, specVendor,
+                                implTitle, implVersion, implVendor,
+                                sealBase, this);
+
+        if (packages.putIfAbsent(name, p) != null)
+            throw new IllegalArgumentException(name);
+
+        return p;
     }
 
     /**
-     * Returns a <tt>Package</tt> that has been defined by this class loader
-     * or any of its ancestors.
+     * Returns a {@code Package} of the given <a href="#binary-name">name</a> that
+     * has been defined by this class loader.
+     *
+     * @param  name The <a href="#binary-name">package name</a>
+     *
+     * @return The {@code Package} of the given name that has been defined
+     *         by this class loader, or {@code null} if not found
+     *
+     * @throws  NullPointerException
+     *          if {@code name} is {@code null}.
+     *
+     * @jvms 5.3 Run-time package
+     *
+     * @since  9
+     * @spec JPMS
+     */
+    public final Package getDefinedPackage(String name) {
+        Objects.requireNonNull(name, "name cannot be null");
+
+        NamedPackage p = packages.get(name);
+        if (p == null)
+            return null;
+
+        return definePackage(name, p.module());
+    }
+
+    /**
+     * Returns all of the {@code Package}s that have been defined by
+     * this class loader.  The returned array has no duplicated {@code Package}s
+     * of the same name.
+     *
+     * @apiNote This method returns an array rather than a {@code Set} or {@code Stream}
+     *          for consistency with the existing {@link #getPackages} method.
+     *
+     * @return The array of {@code Package} objects that have been defined by
+     *         this class loader; or an zero length array if no package has been
+     *         defined by this class loader.
+     *
+     * @jvms 5.3 Run-time package
+     *
+     * @since  9
+     * @spec JPMS
+     */
+    public final Package[] getDefinedPackages() {
+        return packages().toArray(Package[]::new);
+    }
+
+    /**
+     * Finds a package by <a href="#binary-name">name</a> in this class loader and its ancestors.
+     * <p>
+     * If this class loader defines a {@code Package} of the given name,
+     * the {@code Package} is returned. Otherwise, the ancestors of
+     * this class loader are searched recursively (parent by parent)
+     * for a {@code Package} of the given name.
+     *
+     * @apiNote The {@link #getPlatformClassLoader() platform class loader}
+     * may delegate to the application class loader but the application class
+     * loader is not its ancestor.  When invoked on the platform class loader,
+     * this method  will not find packages defined to the application
+     * class loader.
      *
      * @param  name
-     *         The package name
+     *         The <a href="#binary-name">package name</a>
      *
-     * @return  The <tt>Package</tt> corresponding to the given name, or
-     *          <tt>null</tt> if not found
+     * @return The {@code Package} of the given name that has been defined by
+     *         this class loader or its ancestors, or {@code null} if not found.
+     *
+     * @throws  NullPointerException
+     *          if {@code name} is {@code null}.
+     *
+     * @deprecated
+     * If multiple class loaders delegate to each other and define classes
+     * with the same package name, and one such loader relies on the lookup
+     * behavior of {@code getPackage} to return a {@code Package} from
+     * a parent loader, then the properties exposed by the {@code Package}
+     * may not be as expected in the rest of the program.
+     * For example, the {@code Package} will only expose annotations from the
+     * {@code package-info.class} file defined by the parent loader, even if
+     * annotations exist in a {@code package-info.class} file defined by
+     * a child loader.  A more robust approach is to use the
+     * {@link ClassLoader#getDefinedPackage} method which returns
+     * a {@code Package} for the specified class loader.
+     *
+     * @see ClassLoader#getDefinedPackage(String)
      *
      * @since  1.2
+     * @revised 9
+     * @spec JPMS
      */
+    @Deprecated(since="9")
     protected Package getPackage(String name) {
-        Package pkg;
-        synchronized (packages) {
-            pkg = packages.get(name);
-        }
+        Package pkg = getDefinedPackage(name);
         if (pkg == null) {
             if (parent != null) {
                 pkg = parent.getPackage(name);
             } else {
-                pkg = Package.getSystemPackage(name);
-            }
-            if (pkg != null) {
-                synchronized (packages) {
-                    Package pkg2 = packages.get(name);
-                    if (pkg2 == null) {
-                        packages.put(name, pkg);
-                    } else {
-                        pkg = pkg2;
-                    }
-                }
+                pkg = BootLoader.getDefinedPackage(name);
             }
         }
         return pkg;
     }
 
     /**
-     * Returns all of the <tt>Packages</tt> defined by this class loader and
-     * its ancestors.
+     * Returns all of the {@code Package}s that have been defined by
+     * this class loader and its ancestors.  The returned array may contain
+     * more than one {@code Package} object of the same package name, each
+     * defined by a different class loader in the class loader hierarchy.
      *
-     * @return  The array of <tt>Package</tt> objects defined by this
-     *          <tt>ClassLoader</tt>
+     * @apiNote The {@link #getPlatformClassLoader() platform class loader}
+     * may delegate to the application class loader. In other words,
+     * packages in modules defined to the application class loader may be
+     * visible to the platform class loader.  On the other hand,
+     * the application class loader is not its ancestor and hence
+     * when invoked on the platform class loader, this method will not
+     * return any packages defined to the application class loader.
+     *
+     * @return  The array of {@code Package} objects that have been defined by
+     *          this class loader and its ancestors
+     *
+     * @see ClassLoader#getDefinedPackages()
      *
      * @since  1.2
+     * @revised 9
+     * @spec JPMS
      */
     protected Package[] getPackages() {
-        Map<String, Package> map;
-        synchronized (packages) {
-            map = new HashMap<>(packages);
+        Stream<Package> pkgs = packages();
+        ClassLoader ld = parent;
+        while (ld != null) {
+            pkgs = Stream.concat(ld.packages(), pkgs);
+            ld = ld.parent;
         }
-        Package[] pkgs;
-        if (parent != null) {
-            pkgs = parent.getPackages();
-        } else {
-            pkgs = Package.getSystemPackages();
-        }
-        if (pkgs != null) {
-            for (int i = 0; i < pkgs.length; i++) {
-                String pkgName = pkgs[i].getName();
-                if (map.get(pkgName) == null) {
-                    map.put(pkgName, pkgs[i]);
-                }
-            }
-        }
-        return map.values().toArray(new Package[map.size()]);
+        return Stream.concat(BootLoader.packages(), pkgs)
+                     .toArray(Package[]::new);
     }
 
 
+
+    // package-private
+
+    /**
+     * Returns a stream of Packages defined in this class loader
+     */
+    Stream<Package> packages() {
+        return packages.values().stream()
+                       .map(p -> definePackage(p.packageName(), p.module()));
+    }
+
     // -- Native library access --
 
     /**
      * Returns the absolute path name of a native library.  The VM invokes this
      * method to locate the native libraries that belong to classes loaded with
-     * this class loader. If this method returns <tt>null</tt>, the VM
+     * this class loader. If this method returns {@code null}, the VM
      * searches the library along the path specified as the
-     * "<tt>java.library.path</tt>" property.
+     * "{@code java.library.path}" property.
      *
      * @param  libname
      *         The library name
      *
      * @return  The absolute path of the native library
      *
      * @see  System#loadLibrary(String)
      * @see  System#mapLibraryName(String)
      *
      * @since  1.2
      */
     protected String findLibrary(String libname) {
         return null;
     }
 
     /**
      * The inner class NativeLibrary denotes a loaded native library instance.
      * Every classloader contains a vector of loaded native libraries in the
-     * private field <tt>nativeLibraries</tt>.  The native libraries loaded
-     * into the system are entered into the <tt>systemNativeLibraries</tt>
+     * private field {@code nativeLibraries}.  The native libraries loaded
+     * into the system are entered into the {@code systemNativeLibraries}
      * vector.
      *
      * <p> Every native library requires a particular version of JNI. This is
-     * denoted by the private <tt>jniVersion</tt> field.  This field is set by
+     * denoted by the private {@code jniVersion} field.  This field is set by
      * the VM when it loads the library, and used by the VM to pass the correct
      * version of JNI to the native methods.  </p>
      *
      * @see      ClassLoader
      * @since    1.2
      */
     static class NativeLibrary {
+        // the class from which the library is loaded, also indicates
+        // the loader this native library belongs.
+        final Class<?> fromClass;
+        // the canonicalized name of the native library.
+        // or static library name
+        final String name;
+        // Indicates if the native library is linked into the VM
+        final boolean isBuiltin;
+
         // opaque handle to native library, used in native code.
         long handle;
         // the version of JNI environment the native library requires.
-        private int jniVersion;
-        // the class from which the library is loaded, also indicates
-        // the loader this native library belongs.
-        private final Class<?> fromClass;
-        // the canonicalized name of the native library.
-        // or static library name
-        String name;
-        // Indicates if the native library is linked into the VM
-        boolean isBuiltin;
-        // Indicates if the native library is loaded
-        boolean loaded;
-        native void load(String name, boolean isBuiltin);
+        int jniVersion;
 
-        native long find(String name);
-        native void unload(String name, boolean isBuiltin);
+        native boolean load0(String name, boolean isBuiltin);
 
-        public NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
+        native long findEntry(String name);
+
+        NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
             this.name = name;
             this.fromClass = fromClass;
             this.isBuiltin = isBuiltin;
         }
 
-        protected void finalize() {
+        /*
+         * Loads the native library and registers for cleanup when its
+         * associated class loader is unloaded
+         */
+        boolean load() {
+            if (handle != 0) {
+                throw new InternalError("Native library " + name + " has been loaded");
+            }
+
+            if (!load0(name, isBuiltin)) return false;
+
+            // register the class loader for cleanup when unloaded
+            // builtin class loaders are never unloaded
+            ClassLoader loader = fromClass.getClassLoader();
+            if (loader != null &&
+                loader != getBuiltinPlatformClassLoader() &&
+                loader != getBuiltinAppClassLoader()) {
+                CleanerFactory.cleaner().register(loader,
+                        new Unloader(name, handle, isBuiltin));
+            }
+            return true;
+        }
+
+        static boolean loadLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
+            ClassLoader loader =
+                fromClass == null ? null : fromClass.getClassLoader();
+
             synchronized (loadedLibraryNames) {
-                if (fromClass.getClassLoader() != null && loaded) {
-                    /* remove the native library name */
-                    int size = loadedLibraryNames.size();
-                    for (int i = 0; i < size; i++) {
-                        if (name.equals(loadedLibraryNames.elementAt(i))) {
-                            loadedLibraryNames.removeElementAt(i);
-                            break;
+                Map<String, NativeLibrary> libs =
+                    loader != null ? loader.nativeLibraries() : systemNativeLibraries();
+                if (libs.containsKey(name)) {
+                    return true;
+                }
+
+                if (loadedLibraryNames.contains(name)) {
+                    throw new UnsatisfiedLinkError("Native Library " + name +
+                        " already loaded in another classloader");
+                }
+
+                /*
+                 * When a library is being loaded, JNI_OnLoad function can cause
+                 * another loadLibrary invocation that should succeed.
+                 *
+                 * We use a static stack to hold the list of libraries we are
+                 * loading because this can happen only when called by the
+                 * same thread because Runtime.load and Runtime.loadLibrary
+                 * are synchronous.
+                 *
+                 * If there is a pending load operation for the library, we
+                 * immediately return success; otherwise, we raise
+                 * UnsatisfiedLinkError.
+                 */
+                for (NativeLibrary lib : nativeLibraryContext) {
+                    if (name.equals(lib.name)) {
+                        if (loader == lib.fromClass.getClassLoader()) {
+                            return true;
+                        } else {
+                            throw new UnsatisfiedLinkError("Native Library " +
+                                name + " is being loaded in another classloader");
                         }
                     }
-                    /* unload the library. */
-                    ClassLoader.nativeLibraryContext.push(this);
+                }
+                NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
+                // load the native library
+                nativeLibraryContext.push(lib);
+                try {
+                    if (!lib.load()) return false;
+                } finally {
+                    nativeLibraryContext.pop();
+                }
+                // register the loaded native library
+                loadedLibraryNames.add(name);
+                libs.put(name, lib);
+            }
+            return true;
+        }
+
+        // Invoked in the VM to determine the context class in JNI_OnLoad
+        // and JNI_OnUnload
+        static Class<?> getFromClass() {
+            return nativeLibraryContext.peek().fromClass;
+        }
+
+        // native libraries being loaded
+        static Deque<NativeLibrary> nativeLibraryContext = new ArrayDeque<>(8);
+
+        /*
+         * The run() method will be invoked when this class loader becomes
+         * phantom reachable to unload the native library.
+         */
+        static class Unloader implements Runnable {
+            // This represents the context when a native library is unloaded
+            // and getFromClass() will return null,
+            static final NativeLibrary UNLOADER =
+                new NativeLibrary(null, "dummy", false);
+            final String name;
+            final long handle;
+            final boolean isBuiltin;
+
+            Unloader(String name, long handle, boolean isBuiltin) {
+                if (handle == 0) {
+                    throw new IllegalArgumentException(
+                        "Invalid handle for native library " + name);
+                }
+
+                this.name = name;
+                this.handle = handle;
+                this.isBuiltin = isBuiltin;
+            }
+
+            @Override
+            public void run() {
+                synchronized (loadedLibraryNames) {
+                    /* remove the native library name */
+                    loadedLibraryNames.remove(name);
+                    nativeLibraryContext.push(UNLOADER);
                     try {
-                        unload(name, isBuiltin);
+                        unload(name, isBuiltin, handle);
                     } finally {
-                        ClassLoader.nativeLibraryContext.pop();
+                        nativeLibraryContext.pop();
                     }
+
                 }
             }
         }
-        // Invoked in the VM to determine the context class in
-        // JNI_Load/JNI_Unload
-        static Class<?> getFromClass() {
-            return ClassLoader.nativeLibraryContext.peek().fromClass;
-        }
+
+        // JNI FindClass expects the caller class if invoked from JNI_OnLoad
+        // and JNI_OnUnload is NativeLibrary class
+        static native void unload(String name, boolean isBuiltin, long handle);
     }
 
-    // All native library names we've loaded.
-    private static Vector<String> loadedLibraryNames = new Vector<>();
-
-    // Native libraries belonging to system classes.
-    private static Vector<NativeLibrary> systemNativeLibraries
-        = new Vector<>();
-
-    // Native libraries associated with the class loader.
-    private Vector<NativeLibrary> nativeLibraries = new Vector<>();
-
-    // native libraries being loaded/unloaded.
-    private static Stack<NativeLibrary> nativeLibraryContext = new Stack<>();
-
     // The paths searched for libraries
     private static String usr_paths[];
     private static String sys_paths[];
 
-    private static String[] initializePath(String propname) {
-        String ldpath = System.getProperty(propname, "");
-        String ps = File.pathSeparator;
-        int ldlen = ldpath.length();
-        int i, j, n;
-        // Count the separators in the path
-        i = ldpath.indexOf(ps);
-        n = 0;
-        while (i >= 0) {
-            n++;
-            i = ldpath.indexOf(ps, i + 1);
-        }
+    private static String[] initializePath(String propName) {
+        String ldPath = System.getProperty(propName, "");
+        int ldLen = ldPath.length();
+        char ps = File.pathSeparatorChar;
+        int psCount = 0;
 
-        // allocate the array of paths - n :'s = n + 1 path elements
-        String[] paths = new String[n + 1];
-
-        // Fill the array with paths from the ldpath
-        n = i = 0;
-        j = ldpath.indexOf(ps);
-        while (j >= 0) {
-            if (j - i > 0) {
-                paths[n++] = ldpath.substring(i, j);
-            } else if (j - i == 0) {
-                paths[n++] = ".";
+        if (ClassLoaderHelper.allowsQuotedPathElements &&
+            ldPath.indexOf('\"') >= 0) {
+            // First, remove quotes put around quoted parts of paths.
+            // Second, use a quotation mark as a new path separator.
+            // This will preserve any quoted old path separators.
+            char[] buf = new char[ldLen];
+            int bufLen = 0;
+            for (int i = 0; i < ldLen; ++i) {
+                char ch = ldPath.charAt(i);
+                if (ch == '\"') {
+                    while (++i < ldLen &&
+                        (ch = ldPath.charAt(i)) != '\"') {
+                        buf[bufLen++] = ch;
+                    }
+                } else {
+                    if (ch == ps) {
+                        psCount++;
+                        ch = '\"';
+                    }
+                    buf[bufLen++] = ch;
+                }
             }
-            i = j + 1;
-            j = ldpath.indexOf(ps, i);
+            ldPath = new String(buf, 0, bufLen);
+            ldLen = bufLen;
+            ps = '\"';
+        } else {
+            for (int i = ldPath.indexOf(ps); i >= 0;
+                 i = ldPath.indexOf(ps, i + 1)) {
+                psCount++;
+            }
         }
-        paths[n] = ldpath.substring(i, ldlen);
+
+        String[] paths = new String[psCount + 1];
+        int pathStart = 0;
+        for (int j = 0; j < psCount; ++j) {
+            int pathEnd = ldPath.indexOf(ps, pathStart);
+            paths[j] = (pathStart < pathEnd) ?
+                ldPath.substring(pathStart, pathEnd) : ".";
+            pathStart = pathEnd + 1;
+        }
+        paths[psCount] = (pathStart < ldLen) ?
+            ldPath.substring(pathStart, ldLen) : ".";
         return paths;
     }
 
     // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
     static void loadLibrary(Class<?> fromClass, String name,
                             boolean isAbsolute) {
         ClassLoader loader =
             (fromClass == null) ? null : fromClass.getClassLoader();
         if (sys_paths == null) {
             usr_paths = initializePath("java.library.path");
             sys_paths = initializePath("sun.boot.library.path");
         }
         if (isAbsolute) {
             if (loadLibrary0(fromClass, new File(name))) {
                 return;
             }
             throw new UnsatisfiedLinkError("Can't load library: " + name);
         }
         if (loader != null) {
             String libfilename = loader.findLibrary(name);
             if (libfilename != null) {
                 File libfile = new File(libfilename);
                 if (!libfile.isAbsolute()) {
                     throw new UnsatisfiedLinkError(
-    "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
+                        "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
                 }
                 if (loadLibrary0(fromClass, libfile)) {
                     return;
                 }
                 throw new UnsatisfiedLinkError("Can't load " + libfilename);
             }
         }
-        for (int i = 0 ; i < sys_paths.length ; i++) {
-            File libfile = new File(sys_paths[i], System.mapLibraryName(name));
+        for (String sys_path : sys_paths) {
+            File libfile = new File(sys_path, System.mapLibraryName(name));
             if (loadLibrary0(fromClass, libfile)) {
                 return;
             }
             libfile = ClassLoaderHelper.mapAlternativeName(libfile);
             if (libfile != null && loadLibrary0(fromClass, libfile)) {
                 return;
             }
         }
         if (loader != null) {
-            for (int i = 0 ; i < usr_paths.length ; i++) {
-                File libfile = new File(usr_paths[i],
-                                        System.mapLibraryName(name));
+            for (String usr_path : usr_paths) {
+                File libfile = new File(usr_path, System.mapLibraryName(name));
                 if (loadLibrary0(fromClass, libfile)) {
                     return;
                 }
                 libfile = ClassLoaderHelper.mapAlternativeName(libfile);
                 if (libfile != null && loadLibrary0(fromClass, libfile)) {
                     return;
                 }
             }
         }
         // Oops, it failed
-        throw new UnsatisfiedLinkError("no " + name + " in java.library.path");
+        throw new UnsatisfiedLinkError("no " + name +
+            " in java.library.path: " + Arrays.toString(usr_paths));
     }
 
     private static native String findBuiltinLib(String name);
 
     private static boolean loadLibrary0(Class<?> fromClass, final File file) {
         // Check to see if we're attempting to access a static library
         String name = findBuiltinLib(file.getName());
         boolean isBuiltin = (name != null);
         if (!isBuiltin) {
-            boolean exists = AccessController.doPrivileged(
-                new PrivilegedAction<Object>() {
-                    public Object run() {
-                        return file.exists() ? Boolean.TRUE : null;
-                    }})
-                != null;
-            if (!exists) {
-                return false;
-            }
-            try {
-                name = file.getCanonicalPath();
-            } catch (IOException e) {
-                return false;
-            }
-        }
-        ClassLoader loader =
-            (fromClass == null) ? null : fromClass.getClassLoader();
-        Vector<NativeLibrary> libs =
-            loader != null ? loader.nativeLibraries : systemNativeLibraries;
-        synchronized (libs) {
-            int size = libs.size();
-            for (int i = 0; i < size; i++) {
-                NativeLibrary lib = libs.elementAt(i);
-                if (name.equals(lib.name)) {
-                    return true;
-                }
-            }
-
-            synchronized (loadedLibraryNames) {
-                if (loadedLibraryNames.contains(name)) {
-                    throw new UnsatisfiedLinkError
-                        ("Native Library " +
-                         name +
-                         " already loaded in another classloader");
-                }
-                /* If the library is being loaded (must be by the same thread,
-                 * because Runtime.load and Runtime.loadLibrary are
-                 * synchronous). The reason is can occur is that the JNI_OnLoad
-                 * function can cause another loadLibrary invocation.
-                 *
-                 * Thus we can use a static stack to hold the list of libraries
-                 * we are loading.
-                 *
-                 * If there is a pending load operation for the library, we
-                 * immediately return success; otherwise, we raise
-                 * UnsatisfiedLinkError.
-                 */
-                int n = nativeLibraryContext.size();
-                for (int i = 0; i < n; i++) {
-                    NativeLibrary lib = nativeLibraryContext.elementAt(i);
-                    if (name.equals(lib.name)) {
-                        if (loader == lib.fromClass.getClassLoader()) {
-                            return true;
-                        } else {
-                            throw new UnsatisfiedLinkError
-                                ("Native Library " +
-                                 name +
-                                 " is being loaded in another classloader");
+            name = AccessController.doPrivileged(
+                new PrivilegedAction<>() {
+                    public String run() {
+                        try {
+                            return file.exists() ? file.getCanonicalPath() : null;
+                        } catch (IOException e) {
+                            return null;
                         }
                     }
-                }
-                NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
-                nativeLibraryContext.push(lib);
-                try {
-                    lib.load(name, isBuiltin);
-                } finally {
-                    nativeLibraryContext.pop();
-                }
-                if (lib.loaded) {
-                    loadedLibraryNames.addElement(name);
-                    libs.addElement(lib);
-                    return true;
-                }
+                });
+            if (name == null) {
                 return false;
             }
         }
+        return NativeLibrary.loadLibrary(fromClass, name, isBuiltin);
     }
 
-    // Invoked in the VM class linking code.
-    static long findNative(ClassLoader loader, String name) {
-        Vector<NativeLibrary> libs =
-            loader != null ? loader.nativeLibraries : systemNativeLibraries;
-        synchronized (libs) {
-            int size = libs.size();
-            for (int i = 0; i < size; i++) {
-                NativeLibrary lib = libs.elementAt(i);
-                long entry = lib.find(name);
-                if (entry != 0)
-                    return entry;
-            }
+    /*
+     * Invoked in the VM class linking code.
+     */
+    private static long findNative(ClassLoader loader, String entryName) {
+        Map<String, NativeLibrary> libs =
+            loader != null ? loader.nativeLibraries() : systemNativeLibraries();
+        if (libs.isEmpty())
+            return 0;
+
+        // the native libraries map may be updated in another thread
+        // when a native library is being loaded.  No symbol will be
+        // searched from it yet.
+        for (NativeLibrary lib : libs.values()) {
+            long entry = lib.findEntry(entryName);
+            if (entry != 0) return entry;
         }
         return 0;
     }
 
+    // All native library names we've loaded.
+    // This also serves as the lock to obtain nativeLibraries
+    // and write to nativeLibraryContext.
+    private static final Set<String> loadedLibraryNames = new HashSet<>();
+
+    // Native libraries belonging to system classes.
+    private static volatile Map<String, NativeLibrary> systemNativeLibraries;
+
+    // Native libraries associated with the class loader.
+    private volatile Map<String, NativeLibrary> nativeLibraries;
+
+    /*
+     * Returns the native libraries map associated with bootstrap class loader
+     * This method will create the map at the first time when called.
+     */
+    private static Map<String, NativeLibrary> systemNativeLibraries() {
+        Map<String, NativeLibrary> libs = systemNativeLibraries;
+        if (libs == null) {
+            synchronized (loadedLibraryNames) {
+                libs = systemNativeLibraries;
+                if (libs == null) {
+                    libs = systemNativeLibraries = new ConcurrentHashMap<>();
+                }
+            }
+        }
+        return libs;
+    }
+
+    /*
+     * Returns the native libraries map associated with this class loader
+     * This method will create the map at the first time when called.
+     */
+    private Map<String, NativeLibrary> nativeLibraries() {
+        Map<String, NativeLibrary> libs = nativeLibraries;
+        if (libs == null) {
+            synchronized (loadedLibraryNames) {
+                libs = nativeLibraries;
+                if (libs == null) {
+                    libs = nativeLibraries = new ConcurrentHashMap<>();
+                }
+            }
+        }
+        return libs;
+    }
 
     // -- Assertion management --
 
     final Object assertionLock;
 
     // The default toggle for assertion checking.
     // @GuardedBy("assertionLock")
     private boolean defaultAssertionStatus = false;
 
     // Maps String packageName to Boolean package default assertion status Note
     // that the default package is placed under a null map key.  If this field
     // is null then we are delegating assertion status queries to the VM, i.e.,
     // none of this ClassLoader's assertion status modification methods have
     // been invoked.
     // @GuardedBy("assertionLock")
     private Map<String, Boolean> packageAssertionStatus = null;
 
     // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
     // field is null then we are delegating assertion status queries to the VM,
     // i.e., none of this ClassLoader's assertion status modification methods
     // have been invoked.
     // @GuardedBy("assertionLock")
     Map<String, Boolean> classAssertionStatus = null;
 
     /**
      * Sets the default assertion status for this class loader.  This setting
      * determines whether classes loaded by this class loader and initialized
      * in the future will have assertions enabled or disabled by default.
      * This setting may be overridden on a per-package or per-class basis by
      * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
      * #setClassAssertionStatus(String, boolean)}.
      *
      * @param  enabled
-     *         <tt>true</tt> if classes loaded by this class loader will
-     *         henceforth have assertions enabled by default, <tt>false</tt>
+     *         {@code true} if classes loaded by this class loader will
+     *         henceforth have assertions enabled by default, {@code false}
      *         if they will have assertions disabled by default.
      *
      * @since  1.4
      */
     public void setDefaultAssertionStatus(boolean enabled) {
         synchronized (assertionLock) {
             if (classAssertionStatus == null)
                 initializeJavaAssertionMaps();
 
             defaultAssertionStatus = enabled;
         }
     }
 
     /**
      * Sets the package default assertion status for the named package.  The
      * package default assertion status determines the assertion status for
      * classes initialized in the future that belong to the named package or
      * any of its "subpackages".
      *
      * <p> A subpackage of a package named p is any package whose name begins
-     * with "<tt>p.</tt>".  For example, <tt>javax.swing.text</tt> is a
-     * subpackage of <tt>javax.swing</tt>, and both <tt>java.util</tt> and
-     * <tt>java.lang.reflect</tt> are subpackages of <tt>java</tt>.
+     * with "{@code p.}".  For example, {@code javax.swing.text} is a
+     * subpackage of {@code javax.swing}, and both {@code java.util} and
+     * {@code java.lang.reflect} are subpackages of {@code java}.
      *
      * <p> In the event that multiple package defaults apply to a given class,
      * the package default pertaining to the most specific package takes
-     * precedence over the others.  For example, if <tt>javax.lang</tt> and
-     * <tt>javax.lang.reflect</tt> both have package defaults associated with
+     * precedence over the others.  For example, if {@code javax.lang} and
+     * {@code javax.lang.reflect} both have package defaults associated with
      * them, the latter package default applies to classes in
-     * <tt>javax.lang.reflect</tt>.
+     * {@code javax.lang.reflect}.
      *
      * <p> Package defaults take precedence over the class loader's default
      * assertion status, and may be overridden on a per-class basis by invoking
      * {@link #setClassAssertionStatus(String, boolean)}.  </p>
      *
      * @param  packageName
      *         The name of the package whose package default assertion status
-     *         is to be set. A <tt>null</tt> value indicates the unnamed
+     *         is to be set. A {@code null} value indicates the unnamed
      *         package that is "current"
      *         (see section 7.4.2 of
      *         <cite>The Java&trade; Language Specification</cite>.)
      *
      * @param  enabled
-     *         <tt>true</tt> if classes loaded by this classloader and
+     *         {@code true} if classes loaded by this classloader and
      *         belonging to the named package or any of its subpackages will
-     *         have assertions enabled by default, <tt>false</tt> if they will
+     *         have assertions enabled by default, {@code false} if they will
      *         have assertions disabled by default.
      *
      * @since  1.4
      */
     public void setPackageAssertionStatus(String packageName,
                                           boolean enabled) {
         synchronized (assertionLock) {
             if (packageAssertionStatus == null)
                 initializeJavaAssertionMaps();
 
             packageAssertionStatus.put(packageName, enabled);
         }
     }
 
     /**
      * Sets the desired assertion status for the named top-level class in this
      * class loader and any nested classes contained therein.  This setting
      * takes precedence over the class loader's default assertion status, and
      * over any applicable per-package default.  This method has no effect if
      * the named class has already been initialized.  (Once a class is
      * initialized, its assertion status cannot change.)
      *
      * <p> If the named class is not a top-level class, this invocation will
      * have no effect on the actual assertion status of any class. </p>
      *
      * @param  className
      *         The fully qualified class name of the top-level class whose
      *         assertion status is to be set.
      *
      * @param  enabled
-     *         <tt>true</tt> if the named class is to have assertions
-     *         enabled when (and if) it is initialized, <tt>false</tt> if the
+     *         {@code true} if the named class is to have assertions
+     *         enabled when (and if) it is initialized, {@code false} if the
      *         class is to have assertions disabled.
      *
      * @since  1.4
      */
     public void setClassAssertionStatus(String className, boolean enabled) {
         synchronized (assertionLock) {
             if (classAssertionStatus == null)
                 initializeJavaAssertionMaps();
 
             classAssertionStatus.put(className, enabled);
         }
     }
 
     /**
      * Sets the default assertion status for this class loader to
-     * <tt>false</tt> and discards any package defaults or class assertion
+     * {@code false} and discards any package defaults or class assertion
      * status settings associated with the class loader.  This method is
      * provided so that class loaders can be made to ignore any command line or
      * persistent assertion status settings and "start with a clean slate."
      *
      * @since  1.4
      */
     public void clearAssertionStatus() {
         /*
          * Whether or not "Java assertion maps" are initialized, set
          * them to empty maps, effectively ignoring any present settings.
          */
         synchronized (assertionLock) {
             classAssertionStatus = new HashMap<>();
             packageAssertionStatus = new HashMap<>();
             defaultAssertionStatus = false;
         }
     }
 
     /**
      * Returns the assertion status that would be assigned to the specified
      * class if it were to be initialized at the time this method is invoked.
      * If the named class has had its assertion status set, the most recent
      * setting will be returned; otherwise, if any package default assertion
      * status pertains to this class, the most recent setting for the most
      * specific pertinent package default assertion status is returned;
      * otherwise, this class loader's default assertion status is returned.
      * </p>
      *
      * @param  className
      *         The fully qualified class name of the class whose desired
      *         assertion status is being queried.
      *
      * @return  The desired assertion status of the specified class.
      *
      * @see  #setClassAssertionStatus(String, boolean)
      * @see  #setPackageAssertionStatus(String, boolean)
      * @see  #setDefaultAssertionStatus(boolean)
      *
      * @since  1.4
      */
     boolean desiredAssertionStatus(String className) {
         synchronized (assertionLock) {
             // assert classAssertionStatus   != null;
             // assert packageAssertionStatus != null;
 
             // Check for a class entry
             Boolean result = classAssertionStatus.get(className);
             if (result != null)
                 return result.booleanValue();
 
             // Check for most specific package entry
-            int dotIndex = className.lastIndexOf(".");
+            int dotIndex = className.lastIndexOf('.');
             if (dotIndex < 0) { // default package
                 result = packageAssertionStatus.get(null);
                 if (result != null)
                     return result.booleanValue();
             }
             while(dotIndex > 0) {
                 className = className.substring(0, dotIndex);
                 result = packageAssertionStatus.get(className);
                 if (result != null)
                     return result.booleanValue();
-                dotIndex = className.lastIndexOf(".", dotIndex-1);
+                dotIndex = className.lastIndexOf('.', dotIndex-1);
             }
 
             // Return the classloader default
             return defaultAssertionStatus;
         }
     }
 
     // Set up the assertions with information provided by the VM.
     // Note: Should only be called inside a synchronized block
     private void initializeJavaAssertionMaps() {
         // assert Thread.holdsLock(assertionLock);
 
         classAssertionStatus = new HashMap<>();
         packageAssertionStatus = new HashMap<>();
         AssertionStatusDirectives directives = retrieveDirectives();
 
         for(int i = 0; i < directives.classes.length; i++)
             classAssertionStatus.put(directives.classes[i],
                                      directives.classEnabled[i]);
 
         for(int i = 0; i < directives.packages.length; i++)
             packageAssertionStatus.put(directives.packages[i],
                                        directives.packageEnabled[i]);
 
         defaultAssertionStatus = directives.deflt;
     }
 
     // Retrieves the assertion directives from the VM.
     private static native AssertionStatusDirectives retrieveDirectives();
-}
 
 
-class SystemClassLoaderAction
-    implements PrivilegedExceptionAction<ClassLoader> {
-    private ClassLoader parent;
+    // -- Misc --
 
-    SystemClassLoaderAction(ClassLoader parent) {
-        this.parent = parent;
+    /**
+     * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s)
+     * associated with this ClassLoader, creating it if it doesn't already exist.
+     */
+    ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() {
+        ConcurrentHashMap<?, ?> map = classLoaderValueMap;
+        if (map == null) {
+            map = new ConcurrentHashMap<>();
+            boolean set = trySetObjectField("classLoaderValueMap", map);
+            if (!set) {
+                // beaten by someone else
+                map = classLoaderValueMap;
+            }
+        }
+        return map;
     }
 
-    public ClassLoader run() throws Exception {
-        String cls = System.getProperty("java.system.class.loader");
-        if (cls == null) {
-            return parent;
-        }
+    // the storage for ClassLoaderValue(s) associated with this ClassLoader
+    private volatile ConcurrentHashMap<?, ?> classLoaderValueMap;
 
-        Constructor<?> ctor = Class.forName(cls, true, parent)
-            .getDeclaredConstructor(new Class<?>[] { ClassLoader.class });
-        ClassLoader sys = (ClassLoader) ctor.newInstance(
-            new Object[] { parent });
-        Thread.currentThread().setContextClassLoader(sys);
-        return sys;
+    /**
+     * Attempts to atomically set a volatile field in this object. Returns
+     * {@code true} if not beaten by another thread. Avoids the use of
+     * AtomicReferenceFieldUpdater in this class.
+     */
+    private boolean trySetObjectField(String name, Object obj) {
+        Unsafe unsafe = Unsafe.getUnsafe();
+        Class<?> k = ClassLoader.class;
+        long offset;
+        offset = unsafe.objectFieldOffset(k, name);
+        return unsafe.compareAndSetReference(this, offset, null, obj);
+    }
+}
+
+/*
+ * A utility class that will enumerate over an array of enumerations.
+ */
+final class CompoundEnumeration<E> implements Enumeration<E> {
+    private final Enumeration<E>[] enums;
+    private int index;
+
+    public CompoundEnumeration(Enumeration<E>[] enums) {
+        this.enums = enums;
+    }
+
+    private boolean next() {
+        while (index < enums.length) {
+            if (enums[index] != null && enums[index].hasMoreElements()) {
+                return true;
+            }
+            index++;
+        }
+        return false;
+    }
+
+    public boolean hasMoreElements() {
+        return next();
+    }
+
+    public E nextElement() {
+        if (!next()) {
+            throw new NoSuchElementException();
+        }
+        return enums[index].nextElement();
     }
 }