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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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
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 *
 * 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).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package javax.swing;

import java.awt.Component;
import java.awt.Font;
import java.awt.Color;
import java.awt.Insets;
import java.awt.Dimension;
import java.awt.KeyboardFocusManager;
import java.awt.KeyEventPostProcessor;
import java.awt.Toolkit;

import java.awt.event.KeyEvent;

import java.security.AccessController;

import javax.swing.plaf.ComponentUI;
import javax.swing.border.Border;

import javax.swing.event.SwingPropertyChangeSupport;
import java.beans.PropertyChangeListener;

import java.io.Serializable;
import java.io.File;
import java.io.FileInputStream;

import java.util.ArrayList;
import java.util.Properties;
import java.util.StringTokenizer;
import java.util.Vector;
import java.util.Locale;

import sun.awt.SunToolkit;
import sun.awt.OSInfo;
import sun.security.action.GetPropertyAction;
import sun.swing.SwingUtilities2;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Objects;
import sun.awt.AppContext;
import sun.awt.AWTAccessor;


UIManager manages the current look and feel, the set of available look and feels, PropertyChangeListeners that are notified when the look and feel changes, look and feel defaults, and convenience methods for obtaining various default values. 
Specifying the look and feel
 The look and feel can be specified in two distinct ways: by specifying the fully qualified name of the class for the look and feel, or by creating an instance of LookAndFeel and passing it to setLookAndFeel. The following example illustrates setting the look and feel to the system look and feel: 
  UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

The following example illustrates setting the look and feel based on
class name:
  UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
 Once the look and feel has been changed it is imperative to invoke updateUI on all JComponents. The method SwingUtilities.updateComponentTreeUI makes it easy to apply 
updateUI to a containment hierarchy. Refer to it for details. The exact behavior of not invoking 
updateUI after changing the look and feel is unspecified. It is very possible to receive unexpected exceptions, painting problems, or worse. 
Default look and feel
The class used for the default look and feel is chosen in the following
manner:

  
If the system property swing.defaultlaf is non-null, use its value as the default look and feel class name. 
If the Properties file swing.properties
      exists and contains the key swing.defaultlaf,
      use its value as the default look and feel class name. The location
      that is checked for swing.properties may vary depending
      upon the implementation of the Java platform. Typically the
      swing.properties file is located in the conf
      subdirectory of the Java installation directory.
      Refer to the release notes of the implementation being used for
      further details.
  
Otherwise use the cross platform look and feel.

Defaults
 UIManager manages three sets of UIDefaults. In order, they are: 

  
Developer defaults. With few exceptions Swing does not
      alter the developer defaults; these are intended to be modified
      and used by the developer.
  
Look and feel defaults. The look and feel defaults are supplied by the look and feel at the time it is installed as the current look and feel (setLookAndFeel() is invoked). The look and feel defaults can be obtained using the 
      getLookAndFeelDefaults() method. 
System defaults. The system defaults are provided by Swing.
 Invoking any of the various get methods results in checking each of the defaults, in order, returning the first non-null value. For example, invoking UIManager.getString("Table.foreground") results in first checking developer defaults. If the developer defaults contain a value for "Table.foreground" it is returned, otherwise the look and feel defaults are checked, followed by the system defaults. 
 It's important to note that getDefaults returns a custom instance of UIDefaults with this resolution logic built into it. For example, UIManager.getDefaults().getString("Table.foreground") is equivalent to UIManager.getString("Table.foreground"). Both resolve using the algorithm just described. In many places the documentation uses the word defaults to refer to the custom instance of UIDefaults with the resolution logic as previously described. 
 When the look and feel is changed, UIManager alters only the look and feel defaults; the developer and system defaults are not altered by the UIManager in any way. 
 The set of defaults a particular look and feel supports is defined and documented by that look and feel. In addition, each look and feel, or ComponentUI provided by a look and feel, may access the defaults at different times in their life cycle. Some look and feels may aggressively look up defaults, so that changing a default may not have an effect after installing the look and feel. Other look and feels may lazily access defaults so that a change to the defaults may effect an existing look and feel. Finally, other look and feels might not configure themselves from the defaults table in any way. None-the-less it is usually the case that a look and feel expects certain defaults, so that in general a ComponentUI provided by one look and feel will not work with another look and feel. 

Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeans™
has been added to the java.beans package. Please see XMLEncoder. 
Author:
Thomas Ball, Hans Muller
Since:
1.2/**
 * {@code UIManager} manages the current look and feel, the set of
 * available look and feels, {@code PropertyChangeListeners} that
 * are notified when the look and feel changes, look and feel defaults, and
 * convenience methods for obtaining various default values.
 *
 * <h3>Specifying the look and feel</h3>
 *
 * The look and feel can be specified in two distinct ways: by
 * specifying the fully qualified name of the class for the look and
 * feel, or by creating an instance of {@code LookAndFeel} and passing
 * it to {@code setLookAndFeel}. The following example illustrates
 * setting the look and feel to the system look and feel:
 * <pre>
 *   UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
 * </pre>
 * The following example illustrates setting the look and feel based on
 * class name:
 * <pre>
 *   UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
 * </pre>
 * Once the look and feel has been changed it is imperative to invoke
 * {@code updateUI} on all {@code JComponents}. The method {@link
 * SwingUtilities#updateComponentTreeUI} makes it easy to apply {@code
 * updateUI} to a containment hierarchy. Refer to it for
 * details. The exact behavior of not invoking {@code
 * updateUI} after changing the look and feel is
 * unspecified. It is very possible to receive unexpected exceptions,
 * painting problems, or worse.
 *
 * <h3>Default look and feel</h3>
 *
 * The class used for the default look and feel is chosen in the following
 * manner:
 * <ol>
 *   <li>If the system property <code>swing.defaultlaf</code> is
 *       {@code non-null}, use its value as the default look and feel class
 *       name.
 *   <li>If the {@link java.util.Properties} file <code>swing.properties</code>
 *       exists and contains the key <code>swing.defaultlaf</code>,
 *       use its value as the default look and feel class name. The location
 *       that is checked for <code>swing.properties</code> may vary depending
 *       upon the implementation of the Java platform. Typically the
 *       <code>swing.properties</code> file is located in the <code>conf</code>
 *       subdirectory of the Java installation directory.
 *       Refer to the release notes of the implementation being used for
 *       further details.
 *   <li>Otherwise use the cross platform look and feel.
 * </ol>
 *
 * <h3>Defaults</h3>
 *
 * {@code UIManager} manages three sets of {@code UIDefaults}. In order, they
 * are:
 * <ol>
 *   <li>Developer defaults. With few exceptions Swing does not
 *       alter the developer defaults; these are intended to be modified
 *       and used by the developer.
 *   <li>Look and feel defaults. The look and feel defaults are
 *       supplied by the look and feel at the time it is installed as the
 *       current look and feel ({@code setLookAndFeel()} is invoked). The
 *       look and feel defaults can be obtained using the {@code
 *       getLookAndFeelDefaults()} method.
 *   <li>System defaults. The system defaults are provided by Swing.
 * </ol>
 * Invoking any of the various {@code get} methods
 * results in checking each of the defaults, in order, returning
 * the first {@code non-null} value. For example, invoking
 * {@code UIManager.getString("Table.foreground")} results in first
 * checking developer defaults. If the developer defaults contain
 * a value for {@code "Table.foreground"} it is returned, otherwise
 * the look and feel defaults are checked, followed by the system defaults.
 * <p>
 * It's important to note that {@code getDefaults} returns a custom
 * instance of {@code UIDefaults} with this resolution logic built into it.
 * For example, {@code UIManager.getDefaults().getString("Table.foreground")}
 * is equivalent to {@code UIManager.getString("Table.foreground")}. Both
 * resolve using the algorithm just described. In many places the
 * documentation uses the word defaults to refer to the custom instance
 * of {@code UIDefaults} with the resolution logic as previously described.
 * <p>
 * When the look and feel is changed, {@code UIManager} alters only the
 * look and feel defaults; the developer and system defaults are not
 * altered by the {@code UIManager} in any way.
 * <p>
 * The set of defaults a particular look and feel supports is defined
 * and documented by that look and feel. In addition, each look and
 * feel, or {@code ComponentUI} provided by a look and feel, may
 * access the defaults at different times in their life cycle. Some
 * look and feels may aggressively look up defaults, so that changing a
 * default may not have an effect after installing the look and feel.
 * Other look and feels may lazily access defaults so that a change to
 * the defaults may effect an existing look and feel. Finally, other look
 * and feels might not configure themselves from the defaults table in
 * any way. None-the-less it is usually the case that a look and feel
 * expects certain defaults, so that in general
 * a {@code ComponentUI} provided by one look and feel will not
 * work with another look and feel.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Thomas Ball
 * @author Hans Muller
 * @since 1.2
 */
@SuppressWarnings("serial") // Same-version serialization only
public class UIManager implements Serializable
{
    
This class defines the state managed by the UIManager.  For
Swing applications the fields in this class could just as well
be static members of UIManager however we give them
"AppContext"
scope instead so that applets (and potentially multiple lightweight
applications running in a single VM) have their own state. For example,
an applet can alter its look and feel, see setLookAndFeel.
Doing so has no affect on other applets (or the browser).
/**
     * This class defines the state managed by the <code>UIManager</code>.  For
     * Swing applications the fields in this class could just as well
     * be static members of <code>UIManager</code> however we give them
     * "AppContext"
     * scope instead so that applets (and potentially multiple lightweight
     * applications running in a single VM) have their own state. For example,
     * an applet can alter its look and feel, see <code>setLookAndFeel</code>.
     * Doing so has no affect on other applets (or the browser).
     */
    private static class LAFState
    {
        Properties swingProps;
        private UIDefaults[] tables = new UIDefaults[2];

        boolean initialized = false;
        boolean focusPolicyInitialized = false;
        MultiUIDefaults multiUIDefaults = new MultiUIDefaults(tables);
        LookAndFeel lookAndFeel;
        LookAndFeel multiLookAndFeel = null;
        Vector<LookAndFeel> auxLookAndFeels = null;
        SwingPropertyChangeSupport changeSupport;

        LookAndFeelInfo[] installedLAFs;

        UIDefaults getLookAndFeelDefaults() { return tables[0]; }
        void setLookAndFeelDefaults(UIDefaults x) { tables[0] = x; }

        UIDefaults getSystemDefaults() { return tables[1]; }
        void setSystemDefaults(UIDefaults x) { tables[1] = x; }

        
Returns the SwingPropertyChangeSupport for the current
AppContext.  If create is a true, a non-null
SwingPropertyChangeSupport will be returned, if
create is false and this has not been invoked
with true, null will be returned.
/**
         * Returns the SwingPropertyChangeSupport for the current
         * AppContext.  If <code>create</code> is a true, a non-null
         * <code>SwingPropertyChangeSupport</code> will be returned, if
         * <code>create</code> is false and this has not been invoked
         * with true, null will be returned.
         */
        public synchronized SwingPropertyChangeSupport
                                 getPropertyChangeSupport(boolean create) {
            if (create && changeSupport == null) {
                changeSupport = new SwingPropertyChangeSupport(
                                         UIManager.class);
            }
            return changeSupport;
        }
    }




    /* Lock object used in place of class object for synchronization. (4187686)
     */
    private static final Object classLock = new Object();

    
Return the LAFState object, lazily create one if necessary.
All access to the LAFState fields is done via this method,
for example:
    getLAFState().initialized = true;

/**
     * Return the <code>LAFState</code> object, lazily create one if necessary.
     * All access to the <code>LAFState</code> fields is done via this method,
     * for example:
     * <pre>
     *     getLAFState().initialized = true;
     * </pre>
     */
    private static LAFState getLAFState() {
        LAFState rv = (LAFState)SwingUtilities.appContextGet(
                SwingUtilities2.LAF_STATE_KEY);
        if (rv == null) {
            synchronized (classLock) {
                rv = (LAFState)SwingUtilities.appContextGet(
                        SwingUtilities2.LAF_STATE_KEY);
                if (rv == null) {
                    SwingUtilities.appContextPut(
                            SwingUtilities2.LAF_STATE_KEY,
                            (rv = new LAFState()));
                }
            }
        }
        return rv;
    }


    /* Keys used in the <code>swing.properties</code> properties file.
     * See loadUserProperties(), initialize().
     */

    private static final String defaultLAFKey = "swing.defaultlaf";
    private static final String auxiliaryLAFsKey = "swing.auxiliarylaf";
    private static final String multiplexingLAFKey = "swing.plaf.multiplexinglaf";
    private static final String installedLAFsKey = "swing.installedlafs";
    private static final String disableMnemonicKey = "swing.disablenavaids";

    
Return a swing.properties file key for the attribute of specified
look and feel.  The attr is either "name" or "class", a typical
key would be: "swing.installedlaf.windows.name"
/**
     * Return a <code>swing.properties</code> file key for the attribute of specified
     * look and feel.  The attr is either "name" or "class", a typical
     * key would be: "swing.installedlaf.windows.name"
     */
    private static String makeInstalledLAFKey(String laf, String attr) {
        return "swing.installedlaf." + laf + "." + attr;
    }

    
The location of the swing.properties property file is
implementation-specific.
It is typically located in the conf subdirectory of the Java
installation directory. This method returns a bogus filename
if java.home isn't defined.
/**
     * The location of the <code>swing.properties</code> property file is
     * implementation-specific.
     * It is typically located in the <code>conf</code> subdirectory of the Java
     * installation directory. This method returns a bogus filename
     * if <code>java.home</code> isn't defined.
     */
    private static String makeSwingPropertiesFilename() {
        String sep = File.separator;
        // No need to wrap this in a doPrivileged as it's called from
        // a doPrivileged.
        String javaHome = System.getProperty("java.home");
        if (javaHome == null) {
            javaHome = "<java.home undefined>";
        }
        return javaHome + sep + "conf" + sep + "swing.properties";
    }


    
Provides a little information about an installed
LookAndFeel for the sake of configuring a menu or
for initial application set up.
See Also:
getInstalledLookAndFeels.getInstalledLookAndFeels
LookAndFeel/**
     * Provides a little information about an installed
     * <code>LookAndFeel</code> for the sake of configuring a menu or
     * for initial application set up.
     *
     * @see UIManager#getInstalledLookAndFeels
     * @see LookAndFeel
     */
    public static class LookAndFeelInfo {
        private String name;
        private String className;

        
Constructs a UIManagers
LookAndFeelInfo object.
Params:
name –      a String specifying the name of
                     the look and feel
className – a String specifying the name of
                     the class that implements the look and feel/**
         * Constructs a <code>UIManager</code>s
         * <code>LookAndFeelInfo</code> object.
         *
         * @param name      a <code>String</code> specifying the name of
         *                      the look and feel
         * @param className a <code>String</code> specifying the name of
         *                      the class that implements the look and feel
         */
        public LookAndFeelInfo(String name, String className) {
            this.name = name;
            this.className = className;
        }

        
Returns the name of the look and feel in a form suitable
for a menu or other presentation
See Also:
LookAndFeel.getName
Returns:
a String containing the name/**
         * Returns the name of the look and feel in a form suitable
         * for a menu or other presentation
         * @return a <code>String</code> containing the name
         * @see LookAndFeel#getName
         */
        public String getName() {
            return name;
        }

        
Returns the name of the class that implements this look and feel.
See Also:
LookAndFeel
Returns:
the name of the class that implements this
             LookAndFeel/**
         * Returns the name of the class that implements this look and feel.
         * @return the name of the class that implements this
         *              <code>LookAndFeel</code>
         * @see LookAndFeel
         */
        public String getClassName() {
            return className;
        }

        
Returns a string that displays and identifies this
object's properties.
Returns:
a String representation of this object/**
         * Returns a string that displays and identifies this
         * object's properties.
         *
         * @return a <code>String</code> representation of this object
         */
        public String toString() {
            return getClass().getName() + "[" + getName() + " " + getClassName() + "]";
        }
    }


    
The default value of installedLAFS is used when no
swing.properties
file is available or if the file doesn't contain a "swing.installedlafs"
property.
See Also:
initializeInstalledLAFs/**
     * The default value of <code>installedLAFS</code> is used when no
     * <code>swing.properties</code>
     * file is available or if the file doesn't contain a "swing.installedlafs"
     * property.
     *
     * @see #initializeInstalledLAFs
     */
    private static LookAndFeelInfo[] installedLAFs;

    static {
        ArrayList<LookAndFeelInfo> iLAFs = new ArrayList<LookAndFeelInfo>(4);
        iLAFs.add(new LookAndFeelInfo(
                      "Metal", "javax.swing.plaf.metal.MetalLookAndFeel"));
        iLAFs.add(new LookAndFeelInfo(
                      "Nimbus", "javax.swing.plaf.nimbus.NimbusLookAndFeel"));
        iLAFs.add(new LookAndFeelInfo("CDE/Motif",
                  "com.sun.java.swing.plaf.motif.MotifLookAndFeel"));

        // Only include windows on Windows boxs.
        OSInfo.OSType osType = AccessController.doPrivileged(OSInfo.getOSTypeAction());
        if (osType == OSInfo.OSType.WINDOWS) {
            iLAFs.add(new LookAndFeelInfo("Windows",
                        "com.sun.java.swing.plaf.windows.WindowsLookAndFeel"));
            if (Toolkit.getDefaultToolkit().getDesktopProperty(
                    "win.xpstyle.themeActive") != null) {
                iLAFs.add(new LookAndFeelInfo("Windows Classic",
                 "com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel"));
            }
        }
        else if (osType == OSInfo.OSType.MACOSX) {
            iLAFs.add(new LookAndFeelInfo("Mac OS X", "com.apple.laf.AquaLookAndFeel"));
        }
        else {
            // GTK is not shipped on Windows.
            iLAFs.add(new LookAndFeelInfo("GTK+",
                  "com.sun.java.swing.plaf.gtk.GTKLookAndFeel"));
        }
        installedLAFs = iLAFs.toArray(new LookAndFeelInfo[iLAFs.size()]);
    }


    
Returns an array of LookAndFeelInfos representing the LookAndFeel implementations currently available. The LookAndFeelInfo objects can be used by an application to construct a menu of look and feel options for the user, or to determine which look and feel to set at startup time. To avoid the penalty of creating numerous 
LookAndFeel objects, LookAndFeelInfo maintains the class name of the LookAndFeel class, not the actual LookAndFeel instance. 
 The following example illustrates setting the current look and feel from an instance of LookAndFeelInfo: 
  UIManager.setLookAndFeel(info.getClassName());

See Also:
setLookAndFeel
Returns:
an array of LookAndFeelInfo objects/**
     * Returns an array of {@code LookAndFeelInfo}s representing the
     * {@code LookAndFeel} implementations currently available. The
     * <code>LookAndFeelInfo</code> objects can be used by an
     * application to construct a menu of look and feel options for
     * the user, or to determine which look and feel to set at startup
     * time. To avoid the penalty of creating numerous {@code
     * LookAndFeel} objects, {@code LookAndFeelInfo} maintains the
     * class name of the {@code LookAndFeel} class, not the actual
     * {@code LookAndFeel} instance.
     * <p>
     * The following example illustrates setting the current look and feel
     * from an instance of {@code LookAndFeelInfo}:
     * <pre>
     *   UIManager.setLookAndFeel(info.getClassName());
     * </pre>
     *
     * @return an array of <code>LookAndFeelInfo</code> objects
     * @see #setLookAndFeel
     */
    public static LookAndFeelInfo[] getInstalledLookAndFeels() {
        maybeInitialize();
        LookAndFeelInfo[] ilafs = getLAFState().installedLAFs;
        if (ilafs == null) {
            ilafs = installedLAFs;
        }
        LookAndFeelInfo[] rv = new LookAndFeelInfo[ilafs.length];
        System.arraycopy(ilafs, 0, rv, 0, ilafs.length);
        return rv;
    }


    
Sets the set of available look and feels. While this method does not check to ensure all of the LookAndFeelInfos are non-null, it is strongly recommended that only non-null values are supplied in the infos array. 
Params:
infos – set of LookAndFeelInfo objects specifying
       the available look and feels
Throws:
NullPointerException – if infos is null
See Also:
getInstalledLookAndFeels/**
     * Sets the set of available look and feels. While this method does
     * not check to ensure all of the {@code LookAndFeelInfos} are
     * {@code non-null}, it is strongly recommended that only {@code non-null}
     * values are supplied in the {@code infos} array.
     *
     * @param infos set of <code>LookAndFeelInfo</code> objects specifying
     *        the available look and feels
     *
     * @see #getInstalledLookAndFeels
     * @throws NullPointerException if {@code infos} is {@code null}
     */
    public static void setInstalledLookAndFeels(LookAndFeelInfo[] infos)
        throws SecurityException
    {
        maybeInitialize();
        LookAndFeelInfo[] newInfos = new LookAndFeelInfo[infos.length];
        System.arraycopy(infos, 0, newInfos, 0, infos.length);
        getLAFState().installedLAFs = newInfos;
    }


    
Adds the specified look and feel to the set of available look and feels. While this method allows a null info, it is strongly recommended that a non-null value be used. 
Params:
info – a LookAndFeelInfo object that names the
         look and feel and identifies the class that implements it
See Also:
setInstalledLookAndFeels/**
     * Adds the specified look and feel to the set of available look
     * and feels. While this method allows a {@code null} {@code info},
     * it is strongly recommended that a {@code non-null} value be used.
     *
     * @param info a <code>LookAndFeelInfo</code> object that names the
     *          look and feel and identifies the class that implements it
     * @see #setInstalledLookAndFeels
     */
    public static void installLookAndFeel(LookAndFeelInfo info) {
        LookAndFeelInfo[] infos = getInstalledLookAndFeels();
        LookAndFeelInfo[] newInfos = new LookAndFeelInfo[infos.length + 1];
        System.arraycopy(infos, 0, newInfos, 0, infos.length);
        newInfos[infos.length] = info;
        setInstalledLookAndFeels(newInfos);
    }


    
Adds the specified look and feel to the set of available look and feels. While this method does not check the arguments in any way, it is strongly recommended that 
non-null values be supplied. 
Params:
name – descriptive name of the look and feel
className – name of the class that implements the look and feel
See Also:
setInstalledLookAndFeels/**
     * Adds the specified look and feel to the set of available look
     * and feels. While this method does not check the
     * arguments in any way, it is strongly recommended that {@code
     * non-null} values be supplied.
     *
     * @param name descriptive name of the look and feel
     * @param className name of the class that implements the look and feel
     * @see #setInstalledLookAndFeels
     */
    public static void installLookAndFeel(String name, String className) {
        installLookAndFeel(new LookAndFeelInfo(name, className));
    }


    
Returns the current look and feel or null.
See Also:
setLookAndFeel
Returns:
current look and feel, or null/**
     * Returns the current look and feel or <code>null</code>.
     *
     * @return current look and feel, or <code>null</code>
     * @see #setLookAndFeel
     */
    public static LookAndFeel getLookAndFeel() {
        maybeInitialize();
        return getLAFState().lookAndFeel;
    }

    
Creates a supported built-in Java LookAndFeel specified by the given L&F name name. 
Params:
name – a String specifying the name of the built-in look and feel
Throws:
NullPointerException – if name is null
UnsupportedLookAndFeelException – if the built-in Java L&F is not found for the given name or it is not supported by the underlying platform
See Also:
LookAndFeel.getName
LookAndFeel.isSupportedLookAndFeel
Returns:
the built-in LookAndFeel object
Since:
9/**
     * Creates a supported built-in Java {@code LookAndFeel} specified
     * by the given {@code L&F name} name.
     *
     * @param name a {@code String} specifying the name of the built-in
     *             look and feel
     * @return the built-in {@code LookAndFeel} object
     * @throws NullPointerException if {@code name} is {@code null}
     * @throws UnsupportedLookAndFeelException if the built-in Java {@code L&F}
     *         is not found for the given name or it is not supported by the
     *         underlying platform
     *
     * @see LookAndFeel#getName
     * @see LookAndFeel#isSupportedLookAndFeel
     *
     * @since 9
     */
    @SuppressWarnings("deprecation")
    public static LookAndFeel createLookAndFeel(String name)
            throws UnsupportedLookAndFeelException {
        Objects.requireNonNull(name);

        if ("GTK look and feel".equals(name)) {
            name = "GTK+";
        }

        try {
            for (LookAndFeelInfo info : installedLAFs) {
                if (info.getName().equals(name)) {
                    Class<?> cls = Class.forName(UIManager.class.getModule(),
                                                 info.getClassName());
                    LookAndFeel laf =
                        (LookAndFeel) cls.newInstance();
                    if (!laf.isSupportedLookAndFeel()) {
                        break;
                    }
                    return laf;
                }
            }
        } catch (ReflectiveOperationException |
                 IllegalArgumentException ignore) {
        }

        throw new UnsupportedLookAndFeelException(name);
    }

    
Sets the current look and feel to newLookAndFeel. If the current look and feel is non-null 
uninitialize is invoked on it. If newLookAndFeel is non-null, initialize is invoked on it followed by getDefaults. The defaults returned from 
newLookAndFeel.getDefaults() replace those of the defaults from the previous look and feel. If the newLookAndFeel is null, the look and feel defaults are set to null. 
 A value of null can be used to set the look and feel to null. As the LookAndFeel is required for most of Swing to function, setting the LookAndFeel to null is strongly discouraged. 

This is a JavaBeans bound property.
Params:
newLookAndFeel – LookAndFeel to install
Throws:
UnsupportedLookAndFeelException – if newLookAndFeel is non-null and newLookAndFeel.isSupportedLookAndFeel() returns false
See Also:
getLookAndFeel/**
     * Sets the current look and feel to {@code newLookAndFeel}.
     * If the current look and feel is {@code non-null} {@code
     * uninitialize} is invoked on it. If {@code newLookAndFeel} is
     * {@code non-null}, {@code initialize} is invoked on it followed
     * by {@code getDefaults}. The defaults returned from {@code
     * newLookAndFeel.getDefaults()} replace those of the defaults
     * from the previous look and feel. If the {@code newLookAndFeel} is
     * {@code null}, the look and feel defaults are set to {@code null}.
     * <p>
     * A value of {@code null} can be used to set the look and feel
     * to {@code null}. As the {@code LookAndFeel} is required for
     * most of Swing to function, setting the {@code LookAndFeel} to
     * {@code null} is strongly discouraged.
     * <p>
     * This is a JavaBeans bound property.
     *
     * @param newLookAndFeel {@code LookAndFeel} to install
     * @throws UnsupportedLookAndFeelException if
     *          {@code newLookAndFeel} is {@code non-null} and
     *          {@code newLookAndFeel.isSupportedLookAndFeel()} returns
     *          {@code false}
     * @see #getLookAndFeel
     */
    public static void setLookAndFeel(LookAndFeel newLookAndFeel)
        throws UnsupportedLookAndFeelException
    {
        if ((newLookAndFeel != null) && !newLookAndFeel.isSupportedLookAndFeel()) {
            String s = newLookAndFeel.toString() + " not supported on this platform";
            throw new UnsupportedLookAndFeelException(s);
        }

        LAFState lafState = getLAFState();
        LookAndFeel oldLookAndFeel = lafState.lookAndFeel;
        if (oldLookAndFeel != null) {
            oldLookAndFeel.uninitialize();
        }

        lafState.lookAndFeel = newLookAndFeel;
        if (newLookAndFeel != null) {
            sun.swing.DefaultLookup.setDefaultLookup(null);
            newLookAndFeel.initialize();
            lafState.setLookAndFeelDefaults(newLookAndFeel.getDefaults());
        }
        else {
            lafState.setLookAndFeelDefaults(null);
        }

        SwingPropertyChangeSupport changeSupport = lafState.
                                         getPropertyChangeSupport(false);
        if (changeSupport != null) {
            changeSupport.firePropertyChange("lookAndFeel", oldLookAndFeel,
                                             newLookAndFeel);
        }
    }


    
Loads the LookAndFeel specified by the given class name, using the current thread's context class loader, and passes it to setLookAndFeel(LookAndFeel). 
Params:
className –  a string specifying the name of the class that implements
       the look and feel
Throws:
ClassNotFoundException – if the LookAndFeel
          class could not be found
InstantiationException – if a new instance of the class
         couldn't be created
IllegalAccessException – if the class or initializer isn't accessible
UnsupportedLookAndFeelException – if
         lnf.isSupportedLookAndFeel() is false
ClassCastException – if className does not identify a class that extends LookAndFeel
NullPointerException – if className is null/**
     * Loads the {@code LookAndFeel} specified by the given class
     * name, using the current thread's context class loader, and
     * passes it to {@code setLookAndFeel(LookAndFeel)}.
     *
     * @param className  a string specifying the name of the class that implements
     *        the look and feel
     * @throws ClassNotFoundException if the <code>LookAndFeel</code>
     *           class could not be found
     * @throws InstantiationException if a new instance of the class
     *          couldn't be created
     * @throws IllegalAccessException if the class or initializer isn't accessible
     * @throws UnsupportedLookAndFeelException if
     *          <code>lnf.isSupportedLookAndFeel()</code> is false
     * @throws ClassCastException if {@code className} does not identify
     *         a class that extends {@code LookAndFeel}
     * @throws NullPointerException if {@code className} is {@code null}
     */
    @SuppressWarnings("deprecation")
    public static void setLookAndFeel(String className)
        throws ClassNotFoundException,
               InstantiationException,
               IllegalAccessException,
               UnsupportedLookAndFeelException
    {
        if ("javax.swing.plaf.metal.MetalLookAndFeel".equals(className)) {
            // Avoid reflection for the common case of metal.
            setLookAndFeel(new javax.swing.plaf.metal.MetalLookAndFeel());
        }
        else {
            Class<?> lnfClass = SwingUtilities.loadSystemClass(className);
            setLookAndFeel((LookAndFeel)(lnfClass.newInstance()));
        }
    }

    
Returns the name of the LookAndFeel class that implements
the native system look and feel if there is one, otherwise
the name of the default cross platform LookAndFeel
class. This value can be overriden by setting the
swing.systemlaf system property.
See Also:
setLookAndFeel
getCrossPlatformLookAndFeelClassName
Returns:
the String of the LookAndFeel
         class/**
     * Returns the name of the <code>LookAndFeel</code> class that implements
     * the native system look and feel if there is one, otherwise
     * the name of the default cross platform <code>LookAndFeel</code>
     * class. This value can be overriden by setting the
     * <code>swing.systemlaf</code> system property.
     *
     * @return the <code>String</code> of the <code>LookAndFeel</code>
     *          class
     *
     * @see #setLookAndFeel
     * @see #getCrossPlatformLookAndFeelClassName
     */
    public static String getSystemLookAndFeelClassName() {
        String systemLAF = AccessController.doPrivileged(
                             new GetPropertyAction("swing.systemlaf"));
        if (systemLAF != null) {
            return systemLAF;
        }
        OSInfo.OSType osType = AccessController.doPrivileged(OSInfo.getOSTypeAction());
        if (osType == OSInfo.OSType.WINDOWS) {
            return "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
        } else {
            String desktop = AccessController.doPrivileged(new GetPropertyAction("sun.desktop"));
            Toolkit toolkit = Toolkit.getDefaultToolkit();
            if ("gnome".equals(desktop) &&
                    toolkit instanceof SunToolkit &&
                    ((SunToolkit) toolkit).isNativeGTKAvailable()) {
                // May be set on Linux and Solaris boxs.
                return "com.sun.java.swing.plaf.gtk.GTKLookAndFeel";
            }
            if (osType == OSInfo.OSType.MACOSX) {
                if (toolkit.getClass() .getName()
                                       .equals("sun.lwawt.macosx.LWCToolkit")) {
                    return "com.apple.laf.AquaLookAndFeel";
                }
            }
            if (osType == OSInfo.OSType.SOLARIS) {
                return "com.sun.java.swing.plaf.motif.MotifLookAndFeel";
            }
        }
        return getCrossPlatformLookAndFeelClassName();
    }


    
Returns the name of the LookAndFeel class that implements
the default cross platform look and feel -- the Java
Look and Feel (JLF).  This value can be overriden by setting the
swing.crossplatformlaf system property.
See Also:
setLookAndFeel
getSystemLookAndFeelClassName
Returns:
 a string with the JLF implementation-class/**
     * Returns the name of the <code>LookAndFeel</code> class that implements
     * the default cross platform look and feel -- the Java
     * Look and Feel (JLF).  This value can be overriden by setting the
     * <code>swing.crossplatformlaf</code> system property.
     *
     * @return  a string with the JLF implementation-class
     * @see #setLookAndFeel
     * @see #getSystemLookAndFeelClassName
     */
    public static String getCrossPlatformLookAndFeelClassName() {
        String laf = AccessController.doPrivileged(
                             new GetPropertyAction("swing.crossplatformlaf"));
        if (laf != null) {
            return laf;
        }
        return "javax.swing.plaf.metal.MetalLookAndFeel";
    }


    
Returns the defaults. The returned defaults resolve using the
logic specified in the class documentation.
Returns:
a UIDefaults object containing the default values/**
     * Returns the defaults. The returned defaults resolve using the
     * logic specified in the class documentation.
     *
     * @return a <code>UIDefaults</code> object containing the default values
     */
    public static UIDefaults getDefaults() {
        maybeInitialize();
        return getLAFState().multiUIDefaults;
    }

    
Returns a font from the defaults. If the value for key is not a Font, null is returned. 
Params:
key –  an Object specifying the font
Throws:
NullPointerException – if key is null
Returns:
the Font object/**
     * Returns a font from the defaults. If the value for {@code key} is
     * not a {@code Font}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the font
     * @return the <code>Font</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static Font getFont(Object key) {
        return getDefaults().getFont(key);
    }

    
Returns a font from the defaults that is appropriate for the given locale. If the value for key is not a Font, null is returned. 
Params:
key –  an Object specifying the font
l – the Locale for which the font is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the Font object
Since:
1.4/**
     * Returns a font from the defaults that is appropriate
     * for the given locale. If the value for {@code key} is
     * not a {@code Font}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the font
     * @param l the <code>Locale</code> for which the font is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>Font</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static Font getFont(Object key, Locale l) {
        return getDefaults().getFont(key,l);
    }

    
Returns a color from the defaults. If the value for key is not a Color, null is returned. 
Params:
key –  an Object specifying the color
Throws:
NullPointerException – if key is null
Returns:
the Color object/**
     * Returns a color from the defaults. If the value for {@code key} is
     * not a {@code Color}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the color
     * @return the <code>Color</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static Color getColor(Object key) {
        return getDefaults().getColor(key);
    }

    
Returns a color from the defaults that is appropriate for the given locale. If the value for key is not a Color, null is returned. 
Params:
key –  an Object specifying the color
l – the Locale for which the color is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the Color object
Since:
1.4/**
     * Returns a color from the defaults that is appropriate
     * for the given locale. If the value for {@code key} is
     * not a {@code Color}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the color
     * @param l the <code>Locale</code> for which the color is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>Color</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static Color getColor(Object key, Locale l) {
        return getDefaults().getColor(key,l);
    }

    
Returns an Icon from the defaults. If the value for key is not an Icon, null is returned. 
Params:
key –  an Object specifying the icon
Throws:
NullPointerException – if key is null
Returns:
the Icon object/**
     * Returns an <code>Icon</code> from the defaults. If the value for
     * {@code key} is not an {@code Icon}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the icon
     * @return the <code>Icon</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static Icon getIcon(Object key) {
        return getDefaults().getIcon(key);
    }

    
Returns an Icon from the defaults that is appropriate for the given locale. If the value for key is not an Icon, null is returned. 
Params:
key –  an Object specifying the icon
l – the Locale for which the icon is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the Icon object
Since:
1.4/**
     * Returns an <code>Icon</code> from the defaults that is appropriate
     * for the given locale. If the value for
     * {@code key} is not an {@code Icon}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the icon
     * @param l the <code>Locale</code> for which the icon is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>Icon</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static Icon getIcon(Object key, Locale l) {
        return getDefaults().getIcon(key,l);
    }

    
Returns a border from the defaults. If the value for key is not a Border, null is returned. 
Params:
key –  an Object specifying the border
Throws:
NullPointerException – if key is null
Returns:
the Border object/**
     * Returns a border from the defaults. If the value for
     * {@code key} is not a {@code Border}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the border
     * @return the <code>Border</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static Border getBorder(Object key) {
        return getDefaults().getBorder(key);
    }

    
Returns a border from the defaults that is appropriate for the given locale. If the value for key is not a Border, null is returned. 
Params:
key –  an Object specifying the border
l – the Locale for which the border is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the Border object
Since:
1.4/**
     * Returns a border from the defaults that is appropriate
     * for the given locale.  If the value for
     * {@code key} is not a {@code Border}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the border
     * @param l the <code>Locale</code> for which the border is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>Border</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static Border getBorder(Object key, Locale l) {
        return getDefaults().getBorder(key,l);
    }

    
Returns a string from the defaults. If the value for key is not a String, null is returned. 
Params:
key –  an Object specifying the string
Throws:
NullPointerException – if key is null
Returns:
the String/**
     * Returns a string from the defaults. If the value for
     * {@code key} is not a {@code String}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the string
     * @return the <code>String</code>
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static String getString(Object key) {
        return getDefaults().getString(key);
    }

    
Returns a string from the defaults that is appropriate for the given locale. If the value for key is not a String, null is returned. 
Params:
key –  an Object specifying the string
l – the Locale for which the string is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the String
Since:
1.4/**
     * Returns a string from the defaults that is appropriate for the
     * given locale.  If the value for
     * {@code key} is not a {@code String}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the string
     * @param l the <code>Locale</code> for which the string is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>String</code>
     * @since 1.4
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static String getString(Object key, Locale l) {
        return getDefaults().getString(key,l);
    }

    
Returns a string from the defaults that is appropriate for the given locale. If the value for key is not a String, null is returned. 
Params:
key –  an Object specifying the string
c – Component used to determine the locale; null implies the default locale as returned by Locale.getDefault()
Throws:
NullPointerException – if key is null
Returns:
the String/**
     * Returns a string from the defaults that is appropriate for the
     * given locale.  If the value for
     * {@code key} is not a {@code String}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the string
     * @param c {@code Component} used to determine the locale;
     *          {@code null} implies the default locale as
     *          returned by {@code Locale.getDefault()}
     * @return the <code>String</code>
     * @throws NullPointerException if {@code key} is {@code null}
     */
    static String getString(Object key, Component c) {
        Locale l = (c == null) ? Locale.getDefault() : c.getLocale();
        return getString(key, l);
    }

    
Returns an integer from the defaults. If the value for key is not an Integer, or does not exist, 0 is returned. 
Params:
key –  an Object specifying the int
Throws:
NullPointerException – if key is null
Returns:
the int/**
     * Returns an integer from the defaults. If the value for
     * {@code key} is not an {@code Integer}, or does not exist,
     * {@code 0} is returned.
     *
     * @param key  an <code>Object</code> specifying the int
     * @return the int
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static int getInt(Object key) {
        return getDefaults().getInt(key);
    }

    
Returns an integer from the defaults that is appropriate for the given locale. If the value for key is not an Integer, or does not exist, 0 is returned. 
Params:
key –  an Object specifying the int
l – the Locale for which the int is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the int
Since:
1.4/**
     * Returns an integer from the defaults that is appropriate
     * for the given locale. If the value for
     * {@code key} is not an {@code Integer}, or does not exist,
     * {@code 0} is returned.
     *
     * @param key  an <code>Object</code> specifying the int
     * @param l the <code>Locale</code> for which the int is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the int
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static int getInt(Object key, Locale l) {
        return getDefaults().getInt(key,l);
    }

    
Returns a boolean from the defaults which is associated with the key value. If the key is not found or the key doesn't represent a boolean value then false is returned. 
Params:
key –  an Object specifying the key for the desired boolean value
Throws:
NullPointerException – if key is null
Returns:
the boolean value corresponding to the key
Since:
1.4/**
     * Returns a boolean from the defaults which is associated with
     * the key value. If the key is not found or the key doesn't represent
     * a boolean value then {@code false} is returned.
     *
     * @param key  an <code>Object</code> specifying the key for the desired boolean value
     * @return the boolean value corresponding to the key
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static boolean getBoolean(Object key) {
        return getDefaults().getBoolean(key);
    }

    
Returns a boolean from the defaults which is associated with
the key value and the given Locale. If the key is not found or the key doesn't represent a boolean value then false will be returned. 
Params:
key –  an Object specifying the key for the desired
            boolean value
l – the Locale for which the boolean is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the boolean value corresponding to the key
Since:
1.4/**
     * Returns a boolean from the defaults which is associated with
     * the key value and the given <code>Locale</code>. If the key is not
     * found or the key doesn't represent
     * a boolean value then {@code false} will be returned.
     *
     * @param key  an <code>Object</code> specifying the key for the desired
     *             boolean value
     * @param l the <code>Locale</code> for which the boolean is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the boolean value corresponding to the key
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static boolean getBoolean(Object key, Locale l) {
        return getDefaults().getBoolean(key,l);
    }

    
Returns an Insets object from the defaults. If the value for key is not an Insets, null is returned. 
Params:
key –  an Object specifying the Insets object
Throws:
NullPointerException – if key is null
Returns:
the Insets object/**
     * Returns an <code>Insets</code> object from the defaults. If the value
     * for {@code key} is not an {@code Insets}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the <code>Insets</code> object
     * @return the <code>Insets</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static Insets getInsets(Object key) {
        return getDefaults().getInsets(key);
    }

    
Returns an Insets object from the defaults that is appropriate for the given locale. If the value for key is not an Insets, null is returned. 
Params:
key –  an Object specifying the Insets object
l – the Locale for which the object is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the Insets object
Since:
1.4/**
     * Returns an <code>Insets</code> object from the defaults that is
     * appropriate for the given locale. If the value
     * for {@code key} is not an {@code Insets}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the <code>Insets</code> object
     * @param l the <code>Locale</code> for which the object is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>Insets</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static Insets getInsets(Object key, Locale l) {
        return getDefaults().getInsets(key,l);
    }

    
Returns a dimension from the defaults. If the value for key is not a Dimension, null is returned. 
Params:
key –  an Object specifying the dimension object
Throws:
NullPointerException – if key is null
Returns:
the Dimension object/**
     * Returns a dimension from the defaults. If the value
     * for {@code key} is not a {@code Dimension}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the dimension object
     * @return the <code>Dimension</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static Dimension getDimension(Object key) {
        return getDefaults().getDimension(key);
    }

    
Returns a dimension from the defaults that is appropriate for the given locale. If the value for key is not a Dimension, null is returned. 
Params:
key –  an Object specifying the dimension object
l – the Locale for which the object is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the Dimension object
Since:
1.4/**
     * Returns a dimension from the defaults that is appropriate
     * for the given locale. If the value
     * for {@code key} is not a {@code Dimension}, {@code null} is returned.
     *
     * @param key  an <code>Object</code> specifying the dimension object
     * @param l the <code>Locale</code> for which the object is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>Dimension</code> object
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static Dimension getDimension(Object key, Locale l) {
        return getDefaults().getDimension(key,l);
    }

    
Returns an object from the defaults.
Params:
key –  an Object specifying the desired object
Throws:
NullPointerException – if key is null
Returns:
the Object/**
     * Returns an object from the defaults.
     *
     * @param key  an <code>Object</code> specifying the desired object
     * @return the <code>Object</code>
     * @throws NullPointerException if {@code key} is {@code null}
     */
    public static Object get(Object key) {
        return getDefaults().get(key);
    }

    
Returns an object from the defaults that is appropriate for
the given locale.
Params:
key –  an Object specifying the desired object
l – the Locale for which the object is desired; refer to UIDefaults for details on how a null Locale is handled
Throws:
NullPointerException – if key is null
Returns:
the Object
Since:
1.4/**
     * Returns an object from the defaults that is appropriate for
     * the given locale.
     *
     * @param key  an <code>Object</code> specifying the desired object
     * @param l the <code>Locale</code> for which the object is desired; refer
     *        to {@code UIDefaults} for details on how a {@code null}
     *        {@code Locale} is handled
     * @return the <code>Object</code>
     * @throws NullPointerException if {@code key} is {@code null}
     * @since 1.4
     */
    public static Object get(Object key, Locale l) {
        return getDefaults().get(key,l);
    }

    
Stores an object in the developer defaults. This is a cover method for getDefaults().put(key, value). This only effects the developer defaults, not the system or look and feel defaults. 
Params:
key –    an Object specifying the retrieval key
value –  the Object to store; refer to UIDefaults for details on how null is handled
Throws:
NullPointerException – if key is null
See Also:
UIDefaults.put
Returns:
the Object returned by UIDefaults.put/**
     * Stores an object in the developer defaults. This is a cover method
     * for {@code getDefaults().put(key, value)}. This only effects the
     * developer defaults, not the system or look and feel defaults.
     *
     * @param key    an <code>Object</code> specifying the retrieval key
     * @param value  the <code>Object</code> to store; refer to
     *               {@code UIDefaults} for details on how {@code null} is
     *               handled
     * @return the <code>Object</code> returned by {@link UIDefaults#put}
     * @throws NullPointerException if {@code key} is {@code null}
     * @see UIDefaults#put
     */
    public static Object put(Object key, Object value) {
        return getDefaults().put(key, value);
    }

    
Returns the appropriate ComponentUI implementation for target. Typically, this is a cover for getDefaults().getUI(target). However, if an auxiliary look and feel has been installed, this first invokes getUI(target) on the multiplexing look and feel's defaults, and returns that value if it is non-null. 
Params:
target – the JComponent to return the ComponentUI for
Throws:
NullPointerException – if target is null
See Also:
UIDefaults.getUI
Returns:
the ComponentUI object for target/**
     * Returns the appropriate {@code ComponentUI} implementation for
     * {@code target}. Typically, this is a cover for
     * {@code getDefaults().getUI(target)}. However, if an auxiliary
     * look and feel has been installed, this first invokes
     * {@code getUI(target)} on the multiplexing look and feel's
     * defaults, and returns that value if it is {@code non-null}.
     *
     * @param target the <code>JComponent</code> to return the
     *        {@code ComponentUI} for
     * @return the <code>ComponentUI</code> object for {@code target}
     * @throws NullPointerException if {@code target} is {@code null}
     * @see UIDefaults#getUI
     */
    public static ComponentUI getUI(JComponent target) {
        maybeInitialize();
        maybeInitializeFocusPolicy(target);
        ComponentUI ui = null;
        LookAndFeel multiLAF = getLAFState().multiLookAndFeel;
        if (multiLAF != null) {
            // This can return null if the multiplexing look and feel
            // doesn't support a particular UI.
            ui = multiLAF.getDefaults().getUI(target);
        }
        if (ui == null) {
            ui = getDefaults().getUI(target);
        }
        return ui;
    }


    
Returns the UIDefaults from the current look and feel, that were obtained at the time the look and feel was installed. 
 In general, developers should use the UIDefaults returned from getDefaults(). As the current look and feel may expect certain values to exist, altering the UIDefaults returned from this method could have unexpected results. 
See Also:
getDefaults
setLookAndFeel(LookAndFeel)
LookAndFeel.getDefaults
Returns:
UIDefaults from the current look and feel/**
     * Returns the {@code UIDefaults} from the current look and feel,
     * that were obtained at the time the look and feel was installed.
     * <p>
     * In general, developers should use the {@code UIDefaults} returned from
     * {@code getDefaults()}. As the current look and feel may expect
     * certain values to exist, altering the {@code UIDefaults} returned
     * from this method could have unexpected results.
     *
     * @return <code>UIDefaults</code> from the current look and feel
     * @see #getDefaults
     * @see #setLookAndFeel(LookAndFeel)
     * @see LookAndFeel#getDefaults
     */
    public static UIDefaults getLookAndFeelDefaults() {
        maybeInitialize();
        return getLAFState().getLookAndFeelDefaults();
    }

    
Finds the Multiplexing LookAndFeel.
/**
     * Finds the Multiplexing <code>LookAndFeel</code>.
     */
    @SuppressWarnings("deprecation")
    private static LookAndFeel getMultiLookAndFeel() {
        LookAndFeel multiLookAndFeel = getLAFState().multiLookAndFeel;
        if (multiLookAndFeel == null) {
            String defaultName = "javax.swing.plaf.multi.MultiLookAndFeel";
            String className = getLAFState().swingProps.getProperty(multiplexingLAFKey, defaultName);
            try {
                Class<?> lnfClass = SwingUtilities.loadSystemClass(className);
                multiLookAndFeel =
                        (LookAndFeel)lnfClass.newInstance();
            } catch (Exception exc) {
                System.err.println("UIManager: failed loading " + className);
            }
        }
        return multiLookAndFeel;
    }

    
Adds a LookAndFeel to the list of auxiliary look and feels.
The auxiliary look and feels tell the multiplexing look and feel what
other LookAndFeel classes for a component instance are to be used
in addition to the default LookAndFeel class when creating a
multiplexing UI.  The change will only take effect when a new
UI class is created or when the default look and feel is changed
on a component instance.
Note these are not the same as the installed look and feels.
Params:
laf – the LookAndFeel object
See Also:
removeAuxiliaryLookAndFeel
setLookAndFeel
getAuxiliaryLookAndFeels
getInstalledLookAndFeels/**
     * Adds a <code>LookAndFeel</code> to the list of auxiliary look and feels.
     * The auxiliary look and feels tell the multiplexing look and feel what
     * other <code>LookAndFeel</code> classes for a component instance are to be used
     * in addition to the default <code>LookAndFeel</code> class when creating a
     * multiplexing UI.  The change will only take effect when a new
     * UI class is created or when the default look and feel is changed
     * on a component instance.
     * <p>Note these are not the same as the installed look and feels.
     *
     * @param laf the <code>LookAndFeel</code> object
     * @see #removeAuxiliaryLookAndFeel
     * @see #setLookAndFeel
     * @see #getAuxiliaryLookAndFeels
     * @see #getInstalledLookAndFeels
     */
    public static void addAuxiliaryLookAndFeel(LookAndFeel laf) {
        maybeInitialize();

        if (!laf.isSupportedLookAndFeel()) {
            // Ideally we would throw an exception here, but it's too late
            // for that.
            return;
        }
        Vector<LookAndFeel> v = getLAFState().auxLookAndFeels;
        if (v == null) {
            v = new Vector<LookAndFeel>();
        }

        if (!v.contains(laf)) {
            v.addElement(laf);
            laf.initialize();
            getLAFState().auxLookAndFeels = v;

            if (getLAFState().multiLookAndFeel == null) {
                getLAFState().multiLookAndFeel = getMultiLookAndFeel();
            }
        }
    }

    
Removes a LookAndFeel from the list of auxiliary look and feels.
The auxiliary look and feels tell the multiplexing look and feel what
other LookAndFeel classes for a component instance are to be used
in addition to the default LookAndFeel class when creating a
multiplexing UI.  The change will only take effect when a new
UI class is created or when the default look and feel is changed
on a component instance.
Note these are not the same as the installed look and feels.
Params:
laf – the LookAndFeel to be removed
See Also:
removeAuxiliaryLookAndFeel
getAuxiliaryLookAndFeels
setLookAndFeel
getInstalledLookAndFeels
Returns:
true if the LookAndFeel was removed from the list/**
     * Removes a <code>LookAndFeel</code> from the list of auxiliary look and feels.
     * The auxiliary look and feels tell the multiplexing look and feel what
     * other <code>LookAndFeel</code> classes for a component instance are to be used
     * in addition to the default <code>LookAndFeel</code> class when creating a
     * multiplexing UI.  The change will only take effect when a new
     * UI class is created or when the default look and feel is changed
     * on a component instance.
     * <p>Note these are not the same as the installed look and feels.
     *
     * @param laf the {@code LookAndFeel} to be removed
     * @return true if the <code>LookAndFeel</code> was removed from the list
     * @see #removeAuxiliaryLookAndFeel
     * @see #getAuxiliaryLookAndFeels
     * @see #setLookAndFeel
     * @see #getInstalledLookAndFeels
     */
    public static boolean removeAuxiliaryLookAndFeel(LookAndFeel laf) {
        maybeInitialize();

        boolean result;

        Vector<LookAndFeel> v = getLAFState().auxLookAndFeels;
        if ((v == null) || (v.size() == 0)) {
            return false;
        }

        result = v.removeElement(laf);
        if (result) {
            if (v.size() == 0) {
                getLAFState().auxLookAndFeels = null;
                getLAFState().multiLookAndFeel = null;
            } else {
                getLAFState().auxLookAndFeels = v;
            }
        }
        laf.uninitialize();

        return result;
    }

    
Returns the list of auxiliary look and feels (can be null).
The auxiliary look and feels tell the multiplexing look and feel what
other LookAndFeel classes for a component instance are
to be used in addition to the default LookAndFeel class when creating a
multiplexing UI.
Note these are not the same as the installed look and feels.
See Also:
addAuxiliaryLookAndFeel
removeAuxiliaryLookAndFeel
setLookAndFeel
getInstalledLookAndFeels
Returns:
list of auxiliary LookAndFeels or null/**
     * Returns the list of auxiliary look and feels (can be <code>null</code>).
     * The auxiliary look and feels tell the multiplexing look and feel what
     * other <code>LookAndFeel</code> classes for a component instance are
     * to be used in addition to the default LookAndFeel class when creating a
     * multiplexing UI.
     * <p>Note these are not the same as the installed look and feels.
     *
     * @return list of auxiliary <code>LookAndFeel</code>s or <code>null</code>
     * @see #addAuxiliaryLookAndFeel
     * @see #removeAuxiliaryLookAndFeel
     * @see #setLookAndFeel
     * @see #getInstalledLookAndFeels
     */
    public static LookAndFeel[] getAuxiliaryLookAndFeels() {
        maybeInitialize();

        Vector<LookAndFeel> v = getLAFState().auxLookAndFeels;
        if ((v == null) || (v.size() == 0)) {
            return null;
        }
        else {
            LookAndFeel[] rv = new LookAndFeel[v.size()];
            for (int i = 0; i < rv.length; i++) {
                rv[i] = v.elementAt(i);
            }
            return rv;
        }
    }


    
Adds a PropertyChangeListener to the listener list.
The listener is registered for all properties.
Params:
listener –  the PropertyChangeListener to be added
See Also:
PropertyChangeSupport/**
     * Adds a <code>PropertyChangeListener</code> to the listener list.
     * The listener is registered for all properties.
     *
     * @param listener  the <code>PropertyChangeListener</code> to be added
     * @see java.beans.PropertyChangeSupport
     */
    public static void addPropertyChangeListener(PropertyChangeListener listener)
    {
        synchronized (classLock) {
            getLAFState().getPropertyChangeSupport(true).
                             addPropertyChangeListener(listener);
        }
    }


    
Removes a PropertyChangeListener from the listener list.
This removes a PropertyChangeListener that was registered
for all properties.
Params:
listener –  the PropertyChangeListener to be removed
See Also:
PropertyChangeSupport/**
     * Removes a <code>PropertyChangeListener</code> from the listener list.
     * This removes a <code>PropertyChangeListener</code> that was registered
     * for all properties.
     *
     * @param listener  the <code>PropertyChangeListener</code> to be removed
     * @see java.beans.PropertyChangeSupport
     */
    public static void removePropertyChangeListener(PropertyChangeListener listener)
    {
        synchronized (classLock) {
            getLAFState().getPropertyChangeSupport(true).
                          removePropertyChangeListener(listener);
        }
    }


    
Returns an array of all the PropertyChangeListeners added
to this UIManager with addPropertyChangeListener().
Returns:
all of the PropertyChangeListeners added or an empty
        array if no listeners have been added
Since:
1.4/**
     * Returns an array of all the <code>PropertyChangeListener</code>s added
     * to this UIManager with addPropertyChangeListener().
     *
     * @return all of the <code>PropertyChangeListener</code>s added or an empty
     *         array if no listeners have been added
     * @since 1.4
     */
    public static PropertyChangeListener[] getPropertyChangeListeners() {
        synchronized(classLock) {
            return getLAFState().getPropertyChangeSupport(true).
                      getPropertyChangeListeners();
        }
    }

    private static Properties loadSwingProperties()
    {
        /* Don't bother checking for Swing properties if untrusted, as
         * there's no way to look them up without triggering SecurityExceptions.
         */
        if (UIManager.class.getClassLoader() != null) {
            return new Properties();
        }
        else {
            final Properties props = new Properties();

            java.security.AccessController.doPrivileged(
                new java.security.PrivilegedAction<Object>() {
                public Object run() {
                    OSInfo.OSType osType = AccessController.doPrivileged(OSInfo.getOSTypeAction());
                    if (osType == OSInfo.OSType.MACOSX) {
                        props.put(defaultLAFKey, getSystemLookAndFeelClassName());
                    }

                    try {
                        File file = new File(makeSwingPropertiesFilename());

                        if (file.exists()) {
                            // InputStream has been buffered in Properties
                            // class
                            FileInputStream ins = new FileInputStream(file);
                            props.load(ins);
                            ins.close();
                        }
                    }
                    catch (Exception e) {
                        // No such file, or file is otherwise non-readable.
                    }

                    // Check whether any properties were overridden at the
                    // command line.
                    checkProperty(props, defaultLAFKey);
                    checkProperty(props, auxiliaryLAFsKey);
                    checkProperty(props, multiplexingLAFKey);
                    checkProperty(props, installedLAFsKey);
                    checkProperty(props, disableMnemonicKey);
                    // Don't care about return value.
                    return null;
                }
            });
            return props;
        }
    }

    private static void checkProperty(Properties props, String key) {
        // No need to do catch the SecurityException here, this runs
        // in a doPrivileged.
        String value = System.getProperty(key);
        if (value != null) {
            props.put(key, value);
        }
    }


    
If a swing.properties file exist and it has a
swing.installedlafs property
then initialize the installedLAFs field.
See Also:
getInstalledLookAndFeels/**
     * If a <code>swing.properties</code> file exist and it has a
     * <code>swing.installedlafs</code> property
     * then initialize the <code>installedLAFs</code> field.
     *
     * @see #getInstalledLookAndFeels
     */
    private static void initializeInstalledLAFs(Properties swingProps)
    {
        String ilafsString = swingProps.getProperty(installedLAFsKey);
        if (ilafsString == null) {
            return;
        }

        /* Create a vector that contains the value of the swing.installedlafs
         * property.  For example given "swing.installedlafs=motif,windows"
         * lafs = {"motif", "windows"}.
         */
        Vector<String> lafs = new Vector<String>();
        StringTokenizer st = new StringTokenizer(ilafsString, ",", false);
        while (st.hasMoreTokens()) {
            lafs.addElement(st.nextToken());
        }

        /* Look up the name and class for each name in the "swing.installedlafs"
         * list.  If they both exist then add a LookAndFeelInfo to
         * the installedLafs array.
         */
        Vector<LookAndFeelInfo> ilafs = new Vector<LookAndFeelInfo>(lafs.size());
        for (String laf : lafs) {
            String name = swingProps.getProperty(makeInstalledLAFKey(laf, "name"), laf);
            String cls = swingProps.getProperty(makeInstalledLAFKey(laf, "class"));
            if (cls != null) {
                ilafs.addElement(new LookAndFeelInfo(name, cls));
            }
        }

        LookAndFeelInfo[] installedLAFs = new LookAndFeelInfo[ilafs.size()];
        for(int i = 0; i < ilafs.size(); i++) {
            installedLAFs[i] = ilafs.elementAt(i);
        }
        getLAFState().installedLAFs = installedLAFs;
    }


    
If the user has specified a default look and feel, use that.
Otherwise use the look and feel that's native to this platform.
If this code is called after the application has explicitly
set it's look and feel, do nothing.
See Also:
maybeInitialize/**
     * If the user has specified a default look and feel, use that.
     * Otherwise use the look and feel that's native to this platform.
     * If this code is called after the application has explicitly
     * set it's look and feel, do nothing.
     *
     * @see #maybeInitialize
     */
    private static void initializeDefaultLAF(Properties swingProps)
    {
        if (getLAFState().lookAndFeel != null) {
            return;
        }

        // Try to get default LAF from system property, then from AppContext
        // (6653395), then use cross-platform one by default.
        String lafName = null;
        @SuppressWarnings("unchecked")
        HashMap<Object, String> lafData =
                (HashMap) AppContext.getAppContext().remove("swing.lafdata");
        if (lafData != null) {
            lafName = lafData.remove("defaultlaf");
        }
        if (lafName == null) {
            lafName = getCrossPlatformLookAndFeelClassName();
        }
        lafName = swingProps.getProperty(defaultLAFKey, lafName);

        try {
            setLookAndFeel(lafName);
        } catch (Exception e) {
            throw new Error("Cannot load " + lafName);
        }

        // Set any properties passed through AppContext (6653395).
        if (lafData != null) {
            for (Object key: lafData.keySet()) {
                UIManager.put(key, lafData.get(key));
            }
        }
    }


    @SuppressWarnings("deprecation")
    private static void initializeAuxiliaryLAFs(Properties swingProps)
    {
        String auxLookAndFeelNames = swingProps.getProperty(auxiliaryLAFsKey);
        if (auxLookAndFeelNames == null) {
            return;
        }

        Vector<LookAndFeel> auxLookAndFeels = new Vector<LookAndFeel>();

        StringTokenizer p = new StringTokenizer(auxLookAndFeelNames,",");
        String factoryName;

        /* Try to load each LookAndFeel subclass in the list.
         */

        while (p.hasMoreTokens()) {
            String className = p.nextToken();
            try {
                Class<?> lnfClass = SwingUtilities.loadSystemClass(className);
                LookAndFeel newLAF =
                        (LookAndFeel)lnfClass.newInstance();
                newLAF.initialize();
                auxLookAndFeels.addElement(newLAF);
            }
            catch (Exception e) {
                System.err.println("UIManager: failed loading auxiliary look and feel " + className);
            }
        }

        /* If there were problems and no auxiliary look and feels were
         * loaded, make sure we reset auxLookAndFeels to null.
         * Otherwise, we are going to use the MultiLookAndFeel to get
         * all component UI's, so we need to load it now.
         */
        if (auxLookAndFeels.size() == 0) {
            auxLookAndFeels = null;
        }
        else {
            getLAFState().multiLookAndFeel = getMultiLookAndFeel();
            if (getLAFState().multiLookAndFeel == null) {
                auxLookAndFeels = null;
            }
        }

        getLAFState().auxLookAndFeels = auxLookAndFeels;
    }


    private static void initializeSystemDefaults(Properties swingProps) {
        getLAFState().swingProps = swingProps;
    }


    /*
     * This method is called before any code that depends on the
     * <code>AppContext</code> specific LAFState object runs.  When the AppContext
     * corresponds to a set of applets it's possible for this method
     * to be re-entered, which is why we grab a lock before calling
     * initialize().
     */
    private static void maybeInitialize() {
        synchronized (classLock) {
            if (!getLAFState().initialized) {
                getLAFState().initialized = true;
                initialize();
            }
        }
    }

    /*
     * Sets default swing focus traversal policy.
     */
    @SuppressWarnings("deprecation")
    private static void maybeInitializeFocusPolicy(JComponent comp) {
        // Check for JRootPane which indicates that a swing toplevel
        // is coming, in which case a swing default focus policy
        // should be instatiated. See 7125044.
        if (comp instanceof JRootPane) {
            synchronized (classLock) {
                if (!getLAFState().focusPolicyInitialized) {
                    getLAFState().focusPolicyInitialized = true;

                    if (FocusManager.isFocusManagerEnabled()) {
                        KeyboardFocusManager.getCurrentKeyboardFocusManager().
                            setDefaultFocusTraversalPolicy(
                                new LayoutFocusTraversalPolicy());
                    }
                }
            }
        }
    }

    /*
     * Only called by maybeInitialize().
     */
    private static void initialize() {
        Properties swingProps = loadSwingProperties();
        initializeSystemDefaults(swingProps);
        initializeDefaultLAF(swingProps);
        initializeAuxiliaryLAFs(swingProps);
        initializeInstalledLAFs(swingProps);

        // Install Swing's PaintEventDispatcher
        if (RepaintManager.HANDLE_TOP_LEVEL_PAINT) {
            sun.awt.PaintEventDispatcher.setPaintEventDispatcher(
                                        new SwingPaintEventDispatcher());
        }
        // Install a hook that will be invoked if no one consumes the
        // KeyEvent.  If the source isn't a JComponent this will process
        // key bindings, if the source is a JComponent it implies that
        // processKeyEvent was already invoked and thus no need to process
        // the bindings again, unless the Component is disabled, in which
        // case KeyEvents will no longer be dispatched to it so that we
        // handle it here.
        KeyboardFocusManager.getCurrentKeyboardFocusManager().
                addKeyEventPostProcessor(new KeyEventPostProcessor() {
                    public boolean postProcessKeyEvent(KeyEvent e) {
                        Component c = e.getComponent();

                        if ((!(c instanceof JComponent) ||
                             (c != null && !c.isEnabled())) &&
                                JComponent.KeyboardState.shouldProcess(e) &&
                                SwingUtilities.processKeyBindings(e)) {
                            e.consume();
                            return true;
                        }
                        return false;
                    }
                });
        AWTAccessor.getComponentAccessor().
            setRequestFocusController(JComponent.focusController);
    }
}