/*
- * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1994, 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.lang.annotation.Native;
+import java.lang.invoke.MethodHandles;
+import java.lang.constant.Constable;
+import java.lang.constant.ConstantDesc;
+import java.util.Objects;
+import java.util.Optional;
+
+import jdk.internal.HotSpotIntrinsicCandidate;
+import jdk.internal.misc.VM;
+
+import static java.lang.String.COMPACT_STRINGS;
+import static java.lang.String.LATIN1;
+import static java.lang.String.UTF16;
 
 /**
  * The {@code Integer} class wraps a value of the primitive type
  * {@code int} in an object. An object of type {@code Integer}
  * contains a single field whose type is {@code int}.
  *
  * <p>In addition, this class provides several methods for converting
  * an {@code int} to a {@code String} and a {@code String} to an
  * {@code int}, as well as other constants and methods useful when
  * dealing with an {@code int}.
  *
  * <p>Implementation note: The implementations of the "bit twiddling"
  * methods (such as {@link #highestOneBit(int) highestOneBit} and
  * {@link #numberOfTrailingZeros(int) numberOfTrailingZeros}) are
  * based on material from Henry S. Warren, Jr.'s <i>Hacker's
  * Delight</i>, (Addison Wesley, 2002).
  *
  * @author  Lee Boynton
  * @author  Arthur van Hoff
  * @author  Josh Bloch
  * @author  Joseph D. Darcy
- * @since JDK1.0
+ * @since 1.0
  */
-public final class Integer extends Number implements Comparable<Integer> {
+public final class Integer extends Number
+        implements Comparable<Integer>, Constable, ConstantDesc {
     /**
      * A constant holding the minimum value an {@code int} can
      * have, -2<sup>31</sup>.
      */
     @Native public static final int   MIN_VALUE = 0x80000000;
 
     /**
      * A constant holding the maximum value an {@code int} can
      * have, 2<sup>31</sup>-1.
      */
     @Native public static final int   MAX_VALUE = 0x7fffffff;
 
     /**
      * The {@code Class} instance representing the primitive type
      * {@code int}.
      *
-     * @since   JDK1.1
+     * @since   1.1
      */
     @SuppressWarnings("unchecked")
     public static final Class<Integer>  TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
 
     /**
      * All possible chars for representing a number as a String
      */
-    final static char[] digits = {
+    static final char[] digits = {
         '0' , '1' , '2' , '3' , '4' , '5' ,
         '6' , '7' , '8' , '9' , 'a' , 'b' ,
         'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
         'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
         'o' , 'p' , 'q' , 'r' , 's' , 't' ,
         'u' , 'v' , 'w' , 'x' , 'y' , 'z'
     };
 
     /**
      * Returns a string representation of the first argument in the
      * radix specified by the second argument.
      *
      * <p>If the radix is smaller than {@code Character.MIN_RADIX}
      * or larger than {@code Character.MAX_RADIX}, then the radix
      * {@code 10} is used instead.
      *
      * <p>If the first argument is negative, the first element of the
      * result is the ASCII minus character {@code '-'}
      * ({@code '\u005Cu002D'}). If the first argument is not
      * negative, no sign character appears in the result.
      *
      * <p>The remaining characters of the result represent the magnitude
      * of the first argument. If the magnitude is zero, it is
      * represented by a single zero character {@code '0'}
      * ({@code '\u005Cu0030'}); otherwise, the first character of
      * the representation of the magnitude will not be the zero
      * character.  The following ASCII characters are used as digits:
      *
      * <blockquote>
      *   {@code 0123456789abcdefghijklmnopqrstuvwxyz}
      * </blockquote>
      *
      * These are {@code '\u005Cu0030'} through
      * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
      * {@code '\u005Cu007A'}. If {@code radix} is
      * <var>N</var>, then the first <var>N</var> of these characters
      * are used as radix-<var>N</var> digits in the order shown. Thus,
      * the digits for hexadecimal (radix 16) are
      * {@code 0123456789abcdef}. If uppercase letters are
      * desired, the {@link java.lang.String#toUpperCase()} method may
      * be called on the result:
      *
      * <blockquote>
      *  {@code Integer.toString(n, 16).toUpperCase()}
      * </blockquote>
      *
      * @param   i       an integer to be converted to a string.
      * @param   radix   the radix to use in the string representation.
      * @return  a string representation of the argument in the specified radix.
      * @see     java.lang.Character#MAX_RADIX
      * @see     java.lang.Character#MIN_RADIX
      */
     public static String toString(int i, int radix) {
         if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
             radix = 10;
 
         /* Use the faster version */
         if (radix == 10) {
             return toString(i);
         }
 
-        char buf[] = new char[33];
+        if (COMPACT_STRINGS) {
+            byte[] buf = new byte[33];
+            boolean negative = (i < 0);
+            int charPos = 32;
+
+            if (!negative) {
+                i = -i;
+            }
+
+            while (i <= -radix) {
+                buf[charPos--] = (byte)digits[-(i % radix)];
+                i = i / radix;
+            }
+            buf[charPos] = (byte)digits[-i];
+
+            if (negative) {
+                buf[--charPos] = '-';
+            }
+
+            return StringLatin1.newString(buf, charPos, (33 - charPos));
+        }
+        return toStringUTF16(i, radix);
+    }
+
+    private static String toStringUTF16(int i, int radix) {
+        byte[] buf = new byte[33 * 2];
         boolean negative = (i < 0);
         int charPos = 32;
-
         if (!negative) {
             i = -i;
         }
-
         while (i <= -radix) {
-            buf[charPos--] = digits[-(i % radix)];
+            StringUTF16.putChar(buf, charPos--, digits[-(i % radix)]);
             i = i / radix;
         }
-        buf[charPos] = digits[-i];
+        StringUTF16.putChar(buf, charPos, digits[-i]);
 
         if (negative) {
-            buf[--charPos] = '-';
+            StringUTF16.putChar(buf, --charPos, '-');
         }
-
-        return new String(buf, charPos, (33 - charPos));
+        return StringUTF16.newString(buf, charPos, (33 - charPos));
     }
 
     /**
      * Returns a string representation of the first argument as an
      * unsigned integer value in the radix specified by the second
      * argument.
      *
      * <p>If the radix is smaller than {@code Character.MIN_RADIX}
      * or larger than {@code Character.MAX_RADIX}, then the radix
      * {@code 10} is used instead.
      *
      * <p>Note that since the first argument is treated as an unsigned
      * value, no leading sign character is printed.
      *
      * <p>If the magnitude is zero, it is represented by a single zero
      * character {@code '0'} ({@code '\u005Cu0030'}); otherwise,
      * the first character of the representation of the magnitude will
      * not be the zero character.
      *
      * <p>The behavior of radixes and the characters used as digits
      * are the same as {@link #toString(int, int) toString}.
      *
      * @param   i       an integer to be converted to an unsigned string.
      * @param   radix   the radix to use in the string representation.
      * @return  an unsigned string representation of the argument in the specified radix.
      * @see     #toString(int, int)
      * @since 1.8
      */
     public static String toUnsignedString(int i, int radix) {
         return Long.toUnsignedString(toUnsignedLong(i), radix);
     }
 
     /**
      * Returns a string representation of the integer argument as an
      * unsigned integer in base&nbsp;16.
      *
      * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
      * if the argument is negative; otherwise, it is equal to the
      * argument.  This value is converted to a string of ASCII digits
      * in hexadecimal (base&nbsp;16) with no extra leading
      * {@code 0}s.
      *
      * <p>The value of the argument can be recovered from the returned
      * string {@code s} by calling {@link
      * Integer#parseUnsignedInt(String, int)
      * Integer.parseUnsignedInt(s, 16)}.
      *
      * <p>If the unsigned magnitude is zero, it is represented by a
      * single zero character {@code '0'} ({@code '\u005Cu0030'});
      * otherwise, the first character of the representation of the
      * unsigned magnitude will not be the zero character. The
      * following characters are used as hexadecimal digits:
      *
      * <blockquote>
      *  {@code 0123456789abcdef}
      * </blockquote>
      *
      * These are the characters {@code '\u005Cu0030'} through
      * {@code '\u005Cu0039'} and {@code '\u005Cu0061'} through
      * {@code '\u005Cu0066'}. If uppercase letters are
      * desired, the {@link java.lang.String#toUpperCase()} method may
      * be called on the result:
      *
      * <blockquote>
      *  {@code Integer.toHexString(n).toUpperCase()}
      * </blockquote>
      *
      * @param   i   an integer to be converted to a string.
      * @return  the string representation of the unsigned integer value
      *          represented by the argument in hexadecimal (base&nbsp;16).
      * @see #parseUnsignedInt(String, int)
      * @see #toUnsignedString(int, int)
-     * @since   JDK1.0.2
+     * @since   1.0.2
      */
     public static String toHexString(int i) {
         return toUnsignedString0(i, 4);
     }
 
     /**
      * Returns a string representation of the integer argument as an
      * unsigned integer in base&nbsp;8.
      *
      * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
      * if the argument is negative; otherwise, it is equal to the
      * argument.  This value is converted to a string of ASCII digits
      * in octal (base&nbsp;8) with no extra leading {@code 0}s.
      *
      * <p>The value of the argument can be recovered from the returned
      * string {@code s} by calling {@link
      * Integer#parseUnsignedInt(String, int)
      * Integer.parseUnsignedInt(s, 8)}.
      *
      * <p>If the unsigned magnitude is zero, it is represented by a
      * single zero character {@code '0'} ({@code '\u005Cu0030'});
      * otherwise, the first character of the representation of the
      * unsigned magnitude will not be the zero character. The
      * following characters are used as octal digits:
      *
      * <blockquote>
      * {@code 01234567}
      * </blockquote>
      *
      * These are the characters {@code '\u005Cu0030'} through
      * {@code '\u005Cu0037'}.
      *
      * @param   i   an integer to be converted to a string.
      * @return  the string representation of the unsigned integer value
      *          represented by the argument in octal (base&nbsp;8).
      * @see #parseUnsignedInt(String, int)
      * @see #toUnsignedString(int, int)
-     * @since   JDK1.0.2
+     * @since   1.0.2
      */
     public static String toOctalString(int i) {
         return toUnsignedString0(i, 3);
     }
 
     /**
      * Returns a string representation of the integer argument as an
      * unsigned integer in base&nbsp;2.
      *
      * <p>The unsigned integer value is the argument plus 2<sup>32</sup>
      * if the argument is negative; otherwise it is equal to the
      * argument.  This value is converted to a string of ASCII digits
      * in binary (base&nbsp;2) with no extra leading {@code 0}s.
      *
      * <p>The value of the argument can be recovered from the returned
      * string {@code s} by calling {@link
      * Integer#parseUnsignedInt(String, int)
      * Integer.parseUnsignedInt(s, 2)}.
      *
      * <p>If the unsigned magnitude is zero, it is represented by a
      * single zero character {@code '0'} ({@code '\u005Cu0030'});
      * otherwise, the first character of the representation of the
      * unsigned magnitude will not be the zero character. The
      * characters {@code '0'} ({@code '\u005Cu0030'}) and {@code
      * '1'} ({@code '\u005Cu0031'}) are used as binary digits.
      *
      * @param   i   an integer to be converted to a string.
      * @return  the string representation of the unsigned integer value
      *          represented by the argument in binary (base&nbsp;2).
      * @see #parseUnsignedInt(String, int)
      * @see #toUnsignedString(int, int)
-     * @since   JDK1.0.2
+     * @since   1.0.2
      */
     public static String toBinaryString(int i) {
         return toUnsignedString0(i, 1);
     }
 
     /**
      * Convert the integer to an unsigned number.
      */
     private static String toUnsignedString0(int val, int shift) {
         // assert shift > 0 && shift <=5 : "Illegal shift value";
         int mag = Integer.SIZE - Integer.numberOfLeadingZeros(val);
         int chars = Math.max(((mag + (shift - 1)) / shift), 1);
-        char[] buf = new char[chars];
-
-        formatUnsignedInt(val, shift, buf, 0, chars);
-
-        // Use special constructor which takes over "buf".
-        return new String(buf, true);
+        if (COMPACT_STRINGS) {
+            byte[] buf = new byte[chars];
+            formatUnsignedInt(val, shift, buf, 0, chars);
+            return new String(buf, LATIN1);
+        } else {
+            byte[] buf = new byte[chars * 2];
+            formatUnsignedIntUTF16(val, shift, buf, 0, chars);
+            return new String(buf, UTF16);
+        }
     }
 
     /**
-     * Format a long (treated as unsigned) into a character buffer.
+     * Format an {@code int} (treated as unsigned) into a character buffer. If
+     * {@code len} exceeds the formatted ASCII representation of {@code val},
+     * {@code buf} will be padded with leading zeroes.
+     *
      * @param val the unsigned int to format
      * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
      * @param buf the character buffer to write to
      * @param offset the offset in the destination buffer to start at
      * @param len the number of characters to write
-     * @return the lowest character  location used
      */
-     static int formatUnsignedInt(int val, int shift, char[] buf, int offset, int len) {
-        int charPos = len;
+    static void formatUnsignedInt(int val, int shift, char[] buf, int offset, int len) {
+        // assert shift > 0 && shift <=5 : "Illegal shift value";
+        // assert offset >= 0 && offset < buf.length : "illegal offset";
+        // assert len > 0 && (offset + len) <= buf.length : "illegal length";
+        int charPos = offset + len;
         int radix = 1 << shift;
         int mask = radix - 1;
         do {
-            buf[offset + --charPos] = Integer.digits[val & mask];
+            buf[--charPos] = Integer.digits[val & mask];
             val >>>= shift;
-        } while (val != 0 && charPos > 0);
-
-        return charPos;
+        } while (charPos > offset);
     }
 
-    final static char [] DigitTens = {
+    /** byte[]/LATIN1 version    */
+    static void formatUnsignedInt(int val, int shift, byte[] buf, int offset, int len) {
+        int charPos = offset + len;
+        int radix = 1 << shift;
+        int mask = radix - 1;
+        do {
+            buf[--charPos] = (byte)Integer.digits[val & mask];
+            val >>>= shift;
+        } while (charPos > offset);
+    }
+
+    /** byte[]/UTF16 version    */
+    private static void formatUnsignedIntUTF16(int val, int shift, byte[] buf, int offset, int len) {
+        int charPos = offset + len;
+        int radix = 1 << shift;
+        int mask = radix - 1;
+        do {
+            StringUTF16.putChar(buf, --charPos, Integer.digits[val & mask]);
+            val >>>= shift;
+        } while (charPos > offset);
+    }
+
+    static final byte[] DigitTens = {
         '0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
         '1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
         '2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
         '3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
         '4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
         '5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
         '6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
         '7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
         '8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
         '9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
         } ;
 
-    final static char [] DigitOnes = {
+    static final byte[] DigitOnes = {
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
         } ;
 
-        // I use the "invariant division by multiplication" trick to
-        // accelerate Integer.toString.  In particular we want to
-        // avoid division by 10.
-        //
-        // The "trick" has roughly the same performance characteristics
-        // as the "classic" Integer.toString code on a non-JIT VM.
-        // The trick avoids .rem and .div calls but has a longer code
-        // path and is thus dominated by dispatch overhead.  In the
-        // JIT case the dispatch overhead doesn't exist and the
-        // "trick" is considerably faster than the classic code.
-        //
-        // TODO-FIXME: convert (x * 52429) into the equiv shift-add
-        // sequence.
-        //
-        // RE:  Division by Invariant Integers using Multiplication
-        //      T Gralund, P Montgomery
-        //      ACM PLDI 1994
-        //
 
     /**
      * Returns a {@code String} object representing the
      * specified integer. The argument is converted to signed decimal
      * representation and returned as a string, exactly as if the
      * argument and radix 10 were given as arguments to the {@link
      * #toString(int, int)} method.
      *
      * @param   i   an integer to be converted.
      * @return  a string representation of the argument in base&nbsp;10.
      */
+    @HotSpotIntrinsicCandidate
     public static String toString(int i) {
-        if (i == Integer.MIN_VALUE)
-            return "-2147483648";
-        int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
-        char[] buf = new char[size];
-        getChars(i, size, buf);
-        return new String(buf, true);
+        int size = stringSize(i);
+        if (COMPACT_STRINGS) {
+            byte[] buf = new byte[size];
+            getChars(i, size, buf);
+            return new String(buf, LATIN1);
+        } else {
+            byte[] buf = new byte[size * 2];
+            StringUTF16.getChars(i, size, buf);
+            return new String(buf, UTF16);
+        }
     }
 
     /**
      * Returns a string representation of the argument as an unsigned
      * decimal value.
      *
      * The argument is converted to unsigned decimal representation
      * and returned as a string exactly as if the argument and radix
      * 10 were given as arguments to the {@link #toUnsignedString(int,
      * int)} method.
      *
      * @param   i  an integer to be converted to an unsigned string.
      * @return  an unsigned string representation of the argument.
      * @see     #toUnsignedString(int, int)
      * @since 1.8
      */
     public static String toUnsignedString(int i) {
         return Long.toString(toUnsignedLong(i));
     }
 
     /**
      * Places characters representing the integer i into the
      * character array buf. The characters are placed into
      * the buffer backwards starting with the least significant
      * digit at the specified index (exclusive), and working
      * backwards from there.
      *
-     * Will fail if i == Integer.MIN_VALUE
+     * @implNote This method converts positive inputs into negative
+     * values, to cover the Integer.MIN_VALUE case. Converting otherwise
+     * (negative to positive) will expose -Integer.MIN_VALUE that overflows
+     * integer.
+     *
+     * @param i     value to convert
+     * @param index next index, after the least significant digit
+     * @param buf   target buffer, Latin1-encoded
+     * @return index of the most significant digit or minus sign, if present
      */
-    static void getChars(int i, int index, char[] buf) {
+    static int getChars(int i, int index, byte[] buf) {
         int q, r;
         int charPos = index;
-        char sign = 0;
 
-        if (i < 0) {
-            sign = '-';
+        boolean negative = i < 0;
+        if (!negative) {
             i = -i;
         }
 
         // Generate two digits per iteration
-        while (i >= 65536) {
+        while (i <= -100) {
             q = i / 100;
-        // really: r = i - (q * 100);
-            r = i - ((q << 6) + (q << 5) + (q << 2));
+            r = (q * 100) - i;
             i = q;
-            buf [--charPos] = DigitOnes[r];
-            buf [--charPos] = DigitTens[r];
+            buf[--charPos] = DigitOnes[r];
+            buf[--charPos] = DigitTens[r];
         }
 
-        // Fall thru to fast mode for smaller numbers
-        // assert(i <= 65536, i);
-        for (;;) {
-            q = (i * 52429) >>> (16+3);
-            r = i - ((q << 3) + (q << 1));  // r = i-(q*10) ...
-            buf [--charPos] = digits [r];
-            i = q;
-            if (i == 0) break;
+        // We know there are at most two digits left at this point.
+        q = i / 10;
+        r = (q * 10) - i;
+        buf[--charPos] = (byte)('0' + r);
+
+        // Whatever left is the remaining digit.
+        if (q < 0) {
+            buf[--charPos] = (byte)('0' - q);
         }
-        if (sign != 0) {
-            buf [--charPos] = sign;
+
+        if (negative) {
+            buf[--charPos] = (byte)'-';
         }
+        return charPos;
     }
 
-    final static int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
+    // Left here for compatibility reasons, see JDK-8143900.
+    static final int [] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999,
                                       99999999, 999999999, Integer.MAX_VALUE };
 
-    // Requires positive x
+    /**
+     * Returns the string representation size for a given int value.
+     *
+     * @param x int value
+     * @return string size
+     *
+     * @implNote There are other ways to compute this: e.g. binary search,
+     * but values are biased heavily towards zero, and therefore linear search
+     * wins. The iteration results are also routinely inlined in the generated
+     * code after loop unrolling.
+     */
     static int stringSize(int x) {
-        for (int i=0; ; i++)
-            if (x <= sizeTable[i])
-                return i+1;
+        int d = 1;
+        if (x >= 0) {
+            d = 0;
+            x = -x;
+        }
+        int p = -10;
+        for (int i = 1; i < 10; i++) {
+            if (x > p)
+                return i + d;
+            p = 10 * p;
+        }
+        return 10 + d;
     }
 
     /**
      * Parses the string argument as a signed integer in the radix
      * specified by the second argument. The characters in the string
      * must all be digits of the specified radix (as determined by
      * whether {@link java.lang.Character#digit(char, int)} returns a
      * nonnegative value), except that the first character may be an
      * ASCII minus sign {@code '-'} ({@code '\u005Cu002D'}) to
      * indicate a negative value or an ASCII plus sign {@code '+'}
      * ({@code '\u005Cu002B'}) to indicate a positive value. The
      * resulting integer value is returned.
      *
      * <p>An exception of type {@code NumberFormatException} is
      * thrown if any of the following situations occurs:
      * <ul>
      * <li>The first argument is {@code null} or is a string of
      * length zero.
      *
      * <li>The radix is either smaller than
      * {@link java.lang.Character#MIN_RADIX} or
      * larger than {@link java.lang.Character#MAX_RADIX}.
      *
      * <li>Any character of the string is not a digit of the specified
      * radix, except that the first character may be a minus sign
      * {@code '-'} ({@code '\u005Cu002D'}) or plus sign
      * {@code '+'} ({@code '\u005Cu002B'}) provided that the
      * string is longer than length 1.
      *
      * <li>The value represented by the string is not a value of type
      * {@code int}.
      * </ul>
      *
      * <p>Examples:
      * <blockquote><pre>
      * parseInt("0", 10) returns 0
      * parseInt("473", 10) returns 473
      * parseInt("+42", 10) returns 42
      * parseInt("-0", 10) returns 0
      * parseInt("-FF", 16) returns -255
      * parseInt("1100110", 2) returns 102
      * parseInt("2147483647", 10) returns 2147483647
      * parseInt("-2147483648", 10) returns -2147483648
      * parseInt("2147483648", 10) throws a NumberFormatException
      * parseInt("99", 8) throws a NumberFormatException
      * parseInt("Kona", 10) throws a NumberFormatException
      * parseInt("Kona", 27) returns 411787
      * </pre></blockquote>
      *
      * @param      s   the {@code String} containing the integer
      *                  representation to be parsed
      * @param      radix   the radix to be used while parsing {@code s}.
      * @return     the integer represented by the string argument in the
      *             specified radix.
      * @exception  NumberFormatException if the {@code String}
      *             does not contain a parsable {@code int}.
      */
     public static int parseInt(String s, int radix)
                 throws NumberFormatException
     {
         /*
          * WARNING: This method may be invoked early during VM initialization
          * before IntegerCache is initialized. Care must be taken to not use
          * the valueOf method.
          */
 
         if (s == null) {
             throw new NumberFormatException("null");
         }
 
         if (radix < Character.MIN_RADIX) {
             throw new NumberFormatException("radix " + radix +
                                             " less than Character.MIN_RADIX");
         }
 
         if (radix > Character.MAX_RADIX) {
             throw new NumberFormatException("radix " + radix +
                                             " greater than Character.MAX_RADIX");
         }
 
-        int result = 0;
         boolean negative = false;
         int i = 0, len = s.length();
         int limit = -Integer.MAX_VALUE;
-        int multmin;
-        int digit;
 
         if (len > 0) {
             char firstChar = s.charAt(0);
             if (firstChar < '0') { // Possible leading "+" or "-"
                 if (firstChar == '-') {
                     negative = true;
                     limit = Integer.MIN_VALUE;
-                } else if (firstChar != '+')
-                    throw NumberFormatException.forInputString(s);
+                } else if (firstChar != '+') {
+                    throw NumberFormatException.forInputString(s, radix);
+                }
 
-                if (len == 1) // Cannot have lone "+" or "-"
-                    throw NumberFormatException.forInputString(s);
+                if (len == 1) { // Cannot have lone "+" or "-"
+                    throw NumberFormatException.forInputString(s, radix);
+                }
                 i++;
             }
-            multmin = limit / radix;
+            int multmin = limit / radix;
+            int result = 0;
             while (i < len) {
                 // Accumulating negatively avoids surprises near MAX_VALUE
-                digit = Character.digit(s.charAt(i++),radix);
-                if (digit < 0) {
-                    throw NumberFormatException.forInputString(s);
-                }
-                if (result < multmin) {
-                    throw NumberFormatException.forInputString(s);
+                int digit = Character.digit(s.charAt(i++), radix);
+                if (digit < 0 || result < multmin) {
+                    throw NumberFormatException.forInputString(s, radix);
                 }
                 result *= radix;
                 if (result < limit + digit) {
-                    throw NumberFormatException.forInputString(s);
+                    throw NumberFormatException.forInputString(s, radix);
                 }
                 result -= digit;
             }
+            return negative ? result : -result;
         } else {
-            throw NumberFormatException.forInputString(s);
+            throw NumberFormatException.forInputString(s, radix);
         }
-        return negative ? result : -result;
+    }
+
+    /**
+     * Parses the {@link CharSequence} argument as a signed {@code int} in the
+     * specified {@code radix}, beginning at the specified {@code beginIndex}
+     * and extending to {@code endIndex - 1}.
+     *
+     * <p>The method does not take steps to guard against the
+     * {@code CharSequence} being mutated while parsing.
+     *
+     * @param      s   the {@code CharSequence} containing the {@code int}
+     *                  representation to be parsed
+     * @param      beginIndex   the beginning index, inclusive.
+     * @param      endIndex     the ending index, exclusive.
+     * @param      radix   the radix to be used while parsing {@code s}.
+     * @return     the signed {@code int} represented by the subsequence in
+     *             the specified radix.
+     * @throws     NullPointerException  if {@code s} is null.
+     * @throws     IndexOutOfBoundsException  if {@code beginIndex} is
+     *             negative, or if {@code beginIndex} is greater than
+     *             {@code endIndex} or if {@code endIndex} is greater than
+     *             {@code s.length()}.
+     * @throws     NumberFormatException  if the {@code CharSequence} does not
+     *             contain a parsable {@code int} in the specified
+     *             {@code radix}, or if {@code radix} is either smaller than
+     *             {@link java.lang.Character#MIN_RADIX} or larger than
+     *             {@link java.lang.Character#MAX_RADIX}.
+     * @since  9
+     */
+    public static int parseInt(CharSequence s, int beginIndex, int endIndex, int radix)
+                throws NumberFormatException {
+        s = Objects.requireNonNull(s);
+
+        if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
+            throw new IndexOutOfBoundsException();
+        }
+        if (radix < Character.MIN_RADIX) {
+            throw new NumberFormatException("radix " + radix +
+                                            " less than Character.MIN_RADIX");
+        }
+        if (radix > Character.MAX_RADIX) {
+            throw new NumberFormatException("radix " + radix +
+                                            " greater than Character.MAX_RADIX");
+        }
+
+        boolean negative = false;
+        int i = beginIndex;
+        int limit = -Integer.MAX_VALUE;
+
+        if (i < endIndex) {
+            char firstChar = s.charAt(i);
+            if (firstChar < '0') { // Possible leading "+" or "-"
+                if (firstChar == '-') {
+                    negative = true;
+                    limit = Integer.MIN_VALUE;
+                } else if (firstChar != '+') {
+                    throw NumberFormatException.forCharSequence(s, beginIndex,
+                            endIndex, i);
+                }
+                i++;
+                if (i == endIndex) { // Cannot have lone "+" or "-"
+                    throw NumberFormatException.forCharSequence(s, beginIndex,
+                            endIndex, i);
+                }
+            }
+            int multmin = limit / radix;
+            int result = 0;
+            while (i < endIndex) {
+                // Accumulating negatively avoids surprises near MAX_VALUE
+                int digit = Character.digit(s.charAt(i), radix);
+                if (digit < 0 || result < multmin) {
+                    throw NumberFormatException.forCharSequence(s, beginIndex,
+                            endIndex, i);
+                }
+                result *= radix;
+                if (result < limit + digit) {
+                    throw NumberFormatException.forCharSequence(s, beginIndex,
+                            endIndex, i);
+                }
+                i++;
+                result -= digit;
+            }
+            return negative ? result : -result;
+        } else {
+            throw NumberFormatException.forInputString("", radix);
+        }
     }
 
     /**
      * Parses the string argument as a signed decimal integer. The
      * characters in the string must all be decimal digits, except
      * that the first character may be an ASCII minus sign {@code '-'}
      * ({@code '\u005Cu002D'}) to indicate a negative value or an
      * ASCII plus sign {@code '+'} ({@code '\u005Cu002B'}) to
      * indicate a positive value. The resulting integer value is
      * returned, exactly as if the argument and the radix 10 were
      * given as arguments to the {@link #parseInt(java.lang.String,
      * int)} method.
      *
      * @param s    a {@code String} containing the {@code int}
      *             representation to be parsed
      * @return     the integer value represented by the argument in decimal.
      * @exception  NumberFormatException  if the string does not contain a
      *               parsable integer.
      */
     public static int parseInt(String s) throws NumberFormatException {
         return parseInt(s,10);
     }
 
     /**
      * Parses the string argument as an unsigned integer in the radix
      * specified by the second argument.  An unsigned integer maps the
      * values usually associated with negative numbers to positive
      * numbers larger than {@code MAX_VALUE}.
      *
      * The characters in the string must all be digits of the
      * specified radix (as determined by whether {@link
      * java.lang.Character#digit(char, int)} returns a nonnegative
      * value), except that the first character may be an ASCII plus
      * sign {@code '+'} ({@code '\u005Cu002B'}). The resulting
      * integer value is returned.
      *
      * <p>An exception of type {@code NumberFormatException} is
      * thrown if any of the following situations occurs:
      * <ul>
      * <li>The first argument is {@code null} or is a string of
      * length zero.
      *
      * <li>The radix is either smaller than
      * {@link java.lang.Character#MIN_RADIX} or
      * larger than {@link java.lang.Character#MAX_RADIX}.
      *
      * <li>Any character of the string is not a digit of the specified
      * radix, except that the first character may be a plus sign
      * {@code '+'} ({@code '\u005Cu002B'}) provided that the
      * string is longer than length 1.
      *
      * <li>The value represented by the string is larger than the
      * largest unsigned {@code int}, 2<sup>32</sup>-1.
      *
      * </ul>
      *
      *
      * @param      s   the {@code String} containing the unsigned integer
      *                  representation to be parsed
      * @param      radix   the radix to be used while parsing {@code s}.
      * @return     the integer represented by the string argument in the
      *             specified radix.
      * @throws     NumberFormatException if the {@code String}
      *             does not contain a parsable {@code int}.
      * @since 1.8
      */
     public static int parseUnsignedInt(String s, int radix)
                 throws NumberFormatException {
         if (s == null)  {
             throw new NumberFormatException("null");
         }
 
         int len = s.length();
         if (len > 0) {
             char firstChar = s.charAt(0);
             if (firstChar == '-') {
                 throw new
                     NumberFormatException(String.format("Illegal leading minus sign " +
                                                        "on unsigned string %s.", s));
             } else {
                 if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
                     (radix == 10 && len <= 9) ) { // Integer.MAX_VALUE in base 10 is 10 digits
                     return parseInt(s, radix);
                 } else {
                     long ell = Long.parseLong(s, radix);
                     if ((ell & 0xffff_ffff_0000_0000L) == 0) {
                         return (int) ell;
                     } else {
                         throw new
                             NumberFormatException(String.format("String value %s exceeds " +
                                                                 "range of unsigned int.", s));
                     }
                 }
             }
         } else {
-            throw NumberFormatException.forInputString(s);
+            throw NumberFormatException.forInputString(s, radix);
+        }
+    }
+
+    /**
+     * Parses the {@link CharSequence} argument as an unsigned {@code int} in
+     * the specified {@code radix}, beginning at the specified
+     * {@code beginIndex} and extending to {@code endIndex - 1}.
+     *
+     * <p>The method does not take steps to guard against the
+     * {@code CharSequence} being mutated while parsing.
+     *
+     * @param      s   the {@code CharSequence} containing the unsigned
+     *                 {@code int} representation to be parsed
+     * @param      beginIndex   the beginning index, inclusive.
+     * @param      endIndex     the ending index, exclusive.
+     * @param      radix   the radix to be used while parsing {@code s}.
+     * @return     the unsigned {@code int} represented by the subsequence in
+     *             the specified radix.
+     * @throws     NullPointerException  if {@code s} is null.
+     * @throws     IndexOutOfBoundsException  if {@code beginIndex} is
+     *             negative, or if {@code beginIndex} is greater than
+     *             {@code endIndex} or if {@code endIndex} is greater than
+     *             {@code s.length()}.
+     * @throws     NumberFormatException  if the {@code CharSequence} does not
+     *             contain a parsable unsigned {@code int} in the specified
+     *             {@code radix}, or if {@code radix} is either smaller than
+     *             {@link java.lang.Character#MIN_RADIX} or larger than
+     *             {@link java.lang.Character#MAX_RADIX}.
+     * @since  9
+     */
+    public static int parseUnsignedInt(CharSequence s, int beginIndex, int endIndex, int radix)
+                throws NumberFormatException {
+        s = Objects.requireNonNull(s);
+
+        if (beginIndex < 0 || beginIndex > endIndex || endIndex > s.length()) {
+            throw new IndexOutOfBoundsException();
+        }
+        int start = beginIndex, len = endIndex - beginIndex;
+
+        if (len > 0) {
+            char firstChar = s.charAt(start);
+            if (firstChar == '-') {
+                throw new
+                    NumberFormatException(String.format("Illegal leading minus sign " +
+                                                       "on unsigned string %s.", s));
+            } else {
+                if (len <= 5 || // Integer.MAX_VALUE in Character.MAX_RADIX is 6 digits
+                        (radix == 10 && len <= 9)) { // Integer.MAX_VALUE in base 10 is 10 digits
+                    return parseInt(s, start, start + len, radix);
+                } else {
+                    long ell = Long.parseLong(s, start, start + len, radix);
+                    if ((ell & 0xffff_ffff_0000_0000L) == 0) {
+                        return (int) ell;
+                    } else {
+                        throw new
+                            NumberFormatException(String.format("String value %s exceeds " +
+                                                                "range of unsigned int.", s));
+                    }
+                }
+            }
+        } else {
+            throw new NumberFormatException("");
         }
     }
 
     /**
      * Parses the string argument as an unsigned decimal integer. The
      * characters in the string must all be decimal digits, except
-     * that the first character may be an an ASCII plus sign {@code
+     * that the first character may be an ASCII plus sign {@code
      * '+'} ({@code '\u005Cu002B'}). The resulting integer value
      * is returned, exactly as if the argument and the radix 10 were
      * given as arguments to the {@link
      * #parseUnsignedInt(java.lang.String, int)} method.
      *
      * @param s   a {@code String} containing the unsigned {@code int}
      *            representation to be parsed
      * @return    the unsigned integer value represented by the argument in decimal.
      * @throws    NumberFormatException  if the string does not contain a
      *            parsable unsigned integer.
      * @since 1.8
      */
     public static int parseUnsignedInt(String s) throws NumberFormatException {
         return parseUnsignedInt(s, 10);
     }
 
     /**
      * Returns an {@code Integer} object holding the value
      * extracted from the specified {@code String} when parsed
      * with the radix given by the second argument. The first argument
      * is interpreted as representing a signed integer in the radix
      * specified by the second argument, exactly as if the arguments
      * were given to the {@link #parseInt(java.lang.String, int)}
      * method. The result is an {@code Integer} object that
      * represents the integer value specified by the string.
      *
      * <p>In other words, this method returns an {@code Integer}
      * object equal to the value of:
      *
      * <blockquote>
      *  {@code new Integer(Integer.parseInt(s, radix))}
      * </blockquote>
      *
      * @param      s   the string to be parsed.
      * @param      radix the radix to be used in interpreting {@code s}
      * @return     an {@code Integer} object holding the value
      *             represented by the string argument in the specified
      *             radix.
      * @exception NumberFormatException if the {@code String}
      *            does not contain a parsable {@code int}.
      */
     public static Integer valueOf(String s, int radix) throws NumberFormatException {
         return Integer.valueOf(parseInt(s,radix));
     }
 
     /**
      * Returns an {@code Integer} object holding the
      * value of the specified {@code String}. The argument is
      * interpreted as representing a signed decimal integer, exactly
      * as if the argument were given to the {@link
      * #parseInt(java.lang.String)} method. The result is an
      * {@code Integer} object that represents the integer value
      * specified by the string.
      *
      * <p>In other words, this method returns an {@code Integer}
      * object equal to the value of:
      *
      * <blockquote>
      *  {@code new Integer(Integer.parseInt(s))}
      * </blockquote>
      *
      * @param      s   the string to be parsed.
      * @return     an {@code Integer} object holding the value
      *             represented by the string argument.
      * @exception  NumberFormatException  if the string cannot be parsed
      *             as an integer.
      */
     public static Integer valueOf(String s) throws NumberFormatException {
         return Integer.valueOf(parseInt(s, 10));
     }
 
     /**
      * Cache to support the object identity semantics of autoboxing for values between
      * -128 and 127 (inclusive) as required by JLS.
      *
      * The cache is initialized on first usage.  The size of the cache
      * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
      * During VM initialization, java.lang.Integer.IntegerCache.high property
      * may be set and saved in the private system properties in the
-     * sun.misc.VM class.
+     * jdk.internal.misc.VM class.
+     *
+     * WARNING: The cache is archived with CDS and reloaded from the shared
+     * archive at runtime. The archived cache (Integer[]) and Integer objects
+     * reside in the closed archive heap regions. Care should be taken when
+     * changing the implementation and the cache array should not be assigned
+     * with new Integer object(s) after initialization.
      */
 
     private static class IntegerCache {
         static final int low = -128;
         static final int high;
-        static final Integer cache[];
+        static final Integer[] cache;
+        static Integer[] archivedCache;
 
         static {
             // high value may be configured by property
             int h = 127;
             String integerCacheHighPropValue =
-                sun.misc.VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
+                VM.getSavedProperty("java.lang.Integer.IntegerCache.high");
             if (integerCacheHighPropValue != null) {
                 try {
-                    int i = parseInt(integerCacheHighPropValue);
-                    i = Math.max(i, 127);
+                    h = Math.max(parseInt(integerCacheHighPropValue), 127);
                     // Maximum array size is Integer.MAX_VALUE
-                    h = Math.min(i, Integer.MAX_VALUE - (-low) -1);
+                    h = Math.min(h, Integer.MAX_VALUE - (-low) -1);
                 } catch( NumberFormatException nfe) {
                     // If the property cannot be parsed into an int, ignore it.
                 }
             }
             high = h;
 
-            cache = new Integer[(high - low) + 1];
-            int j = low;
-            for(int k = 0; k < cache.length; k++)
-                cache[k] = new Integer(j++);
+            // Load IntegerCache.archivedCache from archive, if possible
+            VM.initializeFromArchive(IntegerCache.class);
+            int size = (high - low) + 1;
 
+            // Use the archived cache if it exists and is large enough
+            if (archivedCache == null || size > archivedCache.length) {
+                Integer[] c = new Integer[size];
+                int j = low;
+                for(int i = 0; i < c.length; i++) {
+                    c[i] = new Integer(j++);
+                }
+                archivedCache = c;
+            }
+            cache = archivedCache;
             // range [-128, 127] must be interned (JLS7 5.1.7)
             assert IntegerCache.high >= 127;
         }
 
         private IntegerCache() {}
     }
 
     /**
      * Returns an {@code Integer} instance representing the specified
      * {@code int} value.  If a new {@code Integer} instance is not
      * required, this method should generally be used in preference to
      * the constructor {@link #Integer(int)}, as this method is likely
      * to yield significantly better space and time performance by
      * caching frequently requested values.
      *
      * This method will always cache values in the range -128 to 127,
      * inclusive, and may cache other values outside of this range.
      *
      * @param  i an {@code int} value.
      * @return an {@code Integer} instance representing {@code i}.
      * @since  1.5
      */
+    @HotSpotIntrinsicCandidate
     public static Integer valueOf(int i) {
         if (i >= IntegerCache.low && i <= IntegerCache.high)
             return IntegerCache.cache[i + (-IntegerCache.low)];
         return new Integer(i);
     }
 
     /**
      * The value of the {@code Integer}.
      *
      * @serial
      */
     private final int value;
 
     /**
      * Constructs a newly allocated {@code Integer} object that
      * represents the specified {@code int} value.
      *
      * @param   value   the value to be represented by the
      *                  {@code Integer} object.
+     *
+     * @deprecated
+     * It is rarely appropriate to use this constructor. The static factory
+     * {@link #valueOf(int)} is generally a better choice, as it is
+     * likely to yield significantly better space and time performance.
      */
+    @Deprecated(since="9")
     public Integer(int value) {
         this.value = value;
     }
 
     /**
      * Constructs a newly allocated {@code Integer} object that
      * represents the {@code int} value indicated by the
      * {@code String} parameter. The string is converted to an
      * {@code int} value in exactly the manner used by the
      * {@code parseInt} method for radix 10.
      *
-     * @param      s   the {@code String} to be converted to an
-     *                 {@code Integer}.
-     * @exception  NumberFormatException  if the {@code String} does not
-     *               contain a parsable integer.
-     * @see        java.lang.Integer#parseInt(java.lang.String, int)
+     * @param   s   the {@code String} to be converted to an {@code Integer}.
+     * @throws      NumberFormatException if the {@code String} does not
+     *              contain a parsable integer.
+     *
+     * @deprecated
+     * It is rarely appropriate to use this constructor.
+     * Use {@link #parseInt(String)} to convert a string to a
+     * {@code int} primitive, or use {@link #valueOf(String)}
+     * to convert a string to an {@code Integer} object.
      */
+    @Deprecated(since="9")
     public Integer(String s) throws NumberFormatException {
         this.value = parseInt(s, 10);
     }
 
     /**
      * Returns the value of this {@code Integer} as a {@code byte}
      * after a narrowing primitive conversion.
      * @jls 5.1.3 Narrowing Primitive Conversions
      */
     public byte byteValue() {
         return (byte)value;
     }
 
     /**
      * Returns the value of this {@code Integer} as a {@code short}
      * after a narrowing primitive conversion.
      * @jls 5.1.3 Narrowing Primitive Conversions
      */
     public short shortValue() {
         return (short)value;
     }
 
     /**
      * Returns the value of this {@code Integer} as an
      * {@code int}.
      */
+    @HotSpotIntrinsicCandidate
     public int intValue() {
         return value;
     }
 
     /**
      * Returns the value of this {@code Integer} as a {@code long}
      * after a widening primitive conversion.
      * @jls 5.1.2 Widening Primitive Conversions
      * @see Integer#toUnsignedLong(int)
      */
     public long longValue() {
         return (long)value;
     }
 
     /**
      * Returns the value of this {@code Integer} as a {@code float}
      * after a widening primitive conversion.
      * @jls 5.1.2 Widening Primitive Conversions
      */
     public float floatValue() {
         return (float)value;
     }
 
     /**
      * Returns the value of this {@code Integer} as a {@code double}
      * after a widening primitive conversion.
      * @jls 5.1.2 Widening Primitive Conversions
      */
     public double doubleValue() {
         return (double)value;
     }
 
     /**
      * Returns a {@code String} object representing this
      * {@code Integer}'s value. The value is converted to signed
      * decimal representation and returned as a string, exactly as if
      * the integer value were given as an argument to the {@link
      * java.lang.Integer#toString(int)} method.
      *
      * @return  a string representation of the value of this object in
      *          base&nbsp;10.
      */
     public String toString() {
         return toString(value);
     }
 
     /**
      * Returns a hash code for this {@code Integer}.
      *
      * @return  a hash code value for this object, equal to the
      *          primitive {@code int} value represented by this
      *          {@code Integer} object.
      */
     @Override
     public int hashCode() {
         return Integer.hashCode(value);
     }
 
     /**
-     * Returns a hash code for a {@code int} value; compatible with
+     * Returns a hash code for an {@code int} value; compatible with
      * {@code Integer.hashCode()}.
      *
      * @param value the value to hash
      * @since 1.8
      *
-     * @return a hash code value for a {@code int} value.
+     * @return a hash code value for an {@code int} value.
      */
     public static int hashCode(int value) {
         return value;
     }
 
     /**
      * Compares this object to the specified object.  The result is
      * {@code true} if and only if the argument is not
      * {@code null} and is an {@code Integer} object that
      * contains the same {@code int} value as this object.
      *
      * @param   obj   the object to compare with.
      * @return  {@code true} if the objects are the same;
      *          {@code false} otherwise.
      */
     public boolean equals(Object obj) {
         if (obj instanceof Integer) {
             return value == ((Integer)obj).intValue();
         }
         return false;
     }
 
     /**
      * Determines the integer value of the system property with the
      * specified name.
      *
      * <p>The first argument is treated as the name of a system
      * property.  System properties are accessible through the {@link
      * java.lang.System#getProperty(java.lang.String)} method. The
      * string value of this property is then interpreted as an integer
      * value using the grammar supported by {@link Integer#decode decode} and
      * an {@code Integer} object representing this value is returned.
      *
      * <p>If there is no property with the specified name, if the
      * specified name is empty or {@code null}, or if the property
      * does not have the correct numeric format, then {@code null} is
      * returned.
      *
      * <p>In other words, this method returns an {@code Integer}
      * object equal to the value of:
      *
      * <blockquote>
      *  {@code getInteger(nm, null)}
      * </blockquote>
      *
      * @param   nm   property name.
      * @return  the {@code Integer} value of the property.
      * @throws  SecurityException for the same reasons as
      *          {@link System#getProperty(String) System.getProperty}
      * @see     java.lang.System#getProperty(java.lang.String)
      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
      */
     public static Integer getInteger(String nm) {
         return getInteger(nm, null);
     }
 
     /**
      * Determines the integer value of the system property with the
      * specified name.
      *
      * <p>The first argument is treated as the name of a system
      * property.  System properties are accessible through the {@link
      * java.lang.System#getProperty(java.lang.String)} method. The
      * string value of this property is then interpreted as an integer
      * value using the grammar supported by {@link Integer#decode decode} and
      * an {@code Integer} object representing this value is returned.
      *
      * <p>The second argument is the default value. An {@code Integer} object
      * that represents the value of the second argument is returned if there
      * is no property of the specified name, if the property does not have
      * the correct numeric format, or if the specified name is empty or
      * {@code null}.
      *
      * <p>In other words, this method returns an {@code Integer} object
      * equal to the value of:
      *
      * <blockquote>
      *  {@code getInteger(nm, new Integer(val))}
      * </blockquote>
      *
      * but in practice it may be implemented in a manner such as:
      *
      * <blockquote><pre>
      * Integer result = getInteger(nm, null);
      * return (result == null) ? new Integer(val) : result;
      * </pre></blockquote>
      *
      * to avoid the unnecessary allocation of an {@code Integer}
      * object when the default value is not needed.
      *
      * @param   nm   property name.
      * @param   val   default value.
      * @return  the {@code Integer} value of the property.
      * @throws  SecurityException for the same reasons as
      *          {@link System#getProperty(String) System.getProperty}
      * @see     java.lang.System#getProperty(java.lang.String)
      * @see     java.lang.System#getProperty(java.lang.String, java.lang.String)
      */
     public static Integer getInteger(String nm, int val) {
         Integer result = getInteger(nm, null);
         return (result == null) ? Integer.valueOf(val) : result;
     }
 
     /**
      * Returns the integer value of the system property with the
      * specified name.  The first argument is treated as the name of a
      * system property.  System properties are accessible through the
      * {@link java.lang.System#getProperty(java.lang.String)} method.
      * The string value of this property is then interpreted as an
      * integer value, as per the {@link Integer#decode decode} method,
      * and an {@code Integer} object representing this value is
      * returned; in summary:
      *
      * <ul><li>If the property value begins with the two ASCII characters
      *         {@code 0x} or the ASCII character {@code #}, not
      *      followed by a minus sign, then the rest of it is parsed as a
      *      hexadecimal integer exactly as by the method
      *      {@link #valueOf(java.lang.String, int)} with radix 16.
      * <li>If the property value begins with the ASCII character
      *     {@code 0} followed by another character, it is parsed as an
      *     octal integer exactly as by the method
      *     {@link #valueOf(java.lang.String, int)} with radix 8.
      * <li>Otherwise, the property value is parsed as a decimal integer
      * exactly as by the method {@link #valueOf(java.lang.String, int)}
      * with radix 10.
      * </ul>
      *
      * <p>The second argument is the default value. The default value is
      * returned if there is no property of the specified name, if the
      * property does not have the correct numeric format, or if the
      * specified name is empty or {@code null}.
      *
      * @param   nm   property name.
      * @param   val   default value.
      * @return  the {@code Integer} value of the property.
      * @throws  SecurityException for the same reasons as
      *          {@link System#getProperty(String) System.getProperty}
      * @see     System#getProperty(java.lang.String)
      * @see     System#getProperty(java.lang.String, java.lang.String)
      */
     public static Integer getInteger(String nm, Integer val) {
         String v = null;
         try {
             v = System.getProperty(nm);
         } catch (IllegalArgumentException | NullPointerException e) {
         }
         if (v != null) {
             try {
                 return Integer.decode(v);
             } catch (NumberFormatException e) {
             }
         }
         return val;
     }
 
     /**
      * Decodes a {@code String} into an {@code Integer}.
      * Accepts decimal, hexadecimal, and octal numbers given
      * by the following grammar:
      *
      * <blockquote>
      * <dl>
      * <dt><i>DecodableString:</i>
      * <dd><i>Sign<sub>opt</sub> DecimalNumeral</i>
      * <dd><i>Sign<sub>opt</sub></i> {@code 0x} <i>HexDigits</i>
      * <dd><i>Sign<sub>opt</sub></i> {@code 0X} <i>HexDigits</i>
      * <dd><i>Sign<sub>opt</sub></i> {@code #} <i>HexDigits</i>
      * <dd><i>Sign<sub>opt</sub></i> {@code 0} <i>OctalDigits</i>
      *
      * <dt><i>Sign:</i>
      * <dd>{@code -}
      * <dd>{@code +}
      * </dl>
      * </blockquote>
      *
      * <i>DecimalNumeral</i>, <i>HexDigits</i>, and <i>OctalDigits</i>
      * are as defined in section 3.10.1 of
      * <cite>The Java&trade; Language Specification</cite>,
      * except that underscores are not accepted between digits.
      *
      * <p>The sequence of characters following an optional
      * sign and/or radix specifier ("{@code 0x}", "{@code 0X}",
      * "{@code #}", or leading zero) is parsed as by the {@code
      * Integer.parseInt} method with the indicated radix (10, 16, or
      * 8).  This sequence of characters must represent a positive
      * value or a {@link NumberFormatException} will be thrown.  The
      * result is negated if first character of the specified {@code
      * String} is the minus sign.  No whitespace characters are
      * permitted in the {@code String}.
      *
      * @param     nm the {@code String} to decode.
      * @return    an {@code Integer} object holding the {@code int}
      *             value represented by {@code nm}
      * @exception NumberFormatException  if the {@code String} does not
      *            contain a parsable integer.
      * @see java.lang.Integer#parseInt(java.lang.String, int)
      */
     public static Integer decode(String nm) throws NumberFormatException {
         int radix = 10;
         int index = 0;
         boolean negative = false;
         Integer result;
 
-        if (nm.length() == 0)
+        if (nm.isEmpty())
             throw new NumberFormatException("Zero length string");
         char firstChar = nm.charAt(0);
         // Handle sign, if present
         if (firstChar == '-') {
             negative = true;
             index++;
         } else if (firstChar == '+')
             index++;
 
         // Handle radix specifier, if present
         if (nm.startsWith("0x", index) || nm.startsWith("0X", index)) {
             index += 2;
             radix = 16;
         }
         else if (nm.startsWith("#", index)) {
             index ++;
             radix = 16;
         }
         else if (nm.startsWith("0", index) && nm.length() > 1 + index) {
             index ++;
             radix = 8;
         }
 
         if (nm.startsWith("-", index) || nm.startsWith("+", index))
             throw new NumberFormatException("Sign character in wrong position");
 
         try {
             result = Integer.valueOf(nm.substring(index), radix);
             result = negative ? Integer.valueOf(-result.intValue()) : result;
         } catch (NumberFormatException e) {
             // If number is Integer.MIN_VALUE, we'll end up here. The next line
             // handles this case, and causes any genuine format error to be
             // rethrown.
             String constant = negative ? ("-" + nm.substring(index))
                                        : nm.substring(index);
             result = Integer.valueOf(constant, radix);
         }
         return result;
     }
 
     /**
      * Compares two {@code Integer} objects numerically.
      *
      * @param   anotherInteger   the {@code Integer} to be compared.
      * @return  the value {@code 0} if this {@code Integer} is
      *          equal to the argument {@code Integer}; a value less than
      *          {@code 0} if this {@code Integer} is numerically less
      *          than the argument {@code Integer}; and a value greater
      *          than {@code 0} if this {@code Integer} is numerically
      *           greater than the argument {@code Integer} (signed
      *           comparison).
      * @since   1.2
      */
     public int compareTo(Integer anotherInteger) {
         return compare(this.value, anotherInteger.value);
     }
 
     /**
      * Compares two {@code int} values numerically.
      * The value returned is identical to what would be returned by:
      * <pre>
      *    Integer.valueOf(x).compareTo(Integer.valueOf(y))
      * </pre>
      *
      * @param  x the first {@code int} to compare
      * @param  y the second {@code int} to compare
      * @return the value {@code 0} if {@code x == y};
      *         a value less than {@code 0} if {@code x < y}; and
      *         a value greater than {@code 0} if {@code x > y}
      * @since 1.7
      */
     public static int compare(int x, int y) {
         return (x < y) ? -1 : ((x == y) ? 0 : 1);
     }
 
     /**
      * Compares two {@code int} values numerically treating the values
      * as unsigned.
      *
      * @param  x the first {@code int} to compare
      * @param  y the second {@code int} to compare
      * @return the value {@code 0} if {@code x == y}; a value less
      *         than {@code 0} if {@code x < y} as unsigned values; and
      *         a value greater than {@code 0} if {@code x > y} as
      *         unsigned values
      * @since 1.8
      */
     public static int compareUnsigned(int x, int y) {
         return compare(x + MIN_VALUE, y + MIN_VALUE);
     }
 
     /**
      * Converts the argument to a {@code long} by an unsigned
      * conversion.  In an unsigned conversion to a {@code long}, the
      * high-order 32 bits of the {@code long} are zero and the
      * low-order 32 bits are equal to the bits of the integer
      * argument.
      *
      * Consequently, zero and positive {@code int} values are mapped
      * to a numerically equal {@code long} value and negative {@code
      * int} values are mapped to a {@code long} value equal to the
      * input plus 2<sup>32</sup>.
      *
      * @param  x the value to convert to an unsigned {@code long}
      * @return the argument converted to {@code long} by an unsigned
      *         conversion
      * @since 1.8
      */
     public static long toUnsignedLong(int x) {
         return ((long) x) & 0xffffffffL;
     }
 
     /**
      * Returns the unsigned quotient of dividing the first argument by
      * the second where each argument and the result is interpreted as
      * an unsigned value.
      *
      * <p>Note that in two's complement arithmetic, the three other
      * basic arithmetic operations of add, subtract, and multiply are
      * bit-wise identical if the two operands are regarded as both
      * being signed or both being unsigned.  Therefore separate {@code
      * addUnsigned}, etc. methods are not provided.
      *
      * @param dividend the value to be divided
      * @param divisor the value doing the dividing
      * @return the unsigned quotient of the first argument divided by
      * the second argument
      * @see #remainderUnsigned
      * @since 1.8
      */
     public static int divideUnsigned(int dividend, int divisor) {
         // In lieu of tricky code, for now just use long arithmetic.
         return (int)(toUnsignedLong(dividend) / toUnsignedLong(divisor));
     }
 
     /**
      * Returns the unsigned remainder from dividing the first argument
      * by the second where each argument and the result is interpreted
      * as an unsigned value.
      *
      * @param dividend the value to be divided
      * @param divisor the value doing the dividing
      * @return the unsigned remainder of the first argument divided by
      * the second argument
      * @see #divideUnsigned
      * @since 1.8
      */
     public static int remainderUnsigned(int dividend, int divisor) {
         // In lieu of tricky code, for now just use long arithmetic.
         return (int)(toUnsignedLong(dividend) % toUnsignedLong(divisor));
     }
 
 
     // Bit twiddling
 
     /**
      * The number of bits used to represent an {@code int} value in two's
      * complement binary form.
      *
      * @since 1.5
      */
     @Native public static final int SIZE = 32;
 
     /**
-     * The number of bytes used to represent a {@code int} value in two's
+     * The number of bytes used to represent an {@code int} value in two's
      * complement binary form.
      *
      * @since 1.8
      */
     public static final int BYTES = SIZE / Byte.SIZE;
 
     /**
      * Returns an {@code int} value with at most a single one-bit, in the
      * position of the highest-order ("leftmost") one-bit in the specified
      * {@code int} value.  Returns zero if the specified value has no
      * one-bits in its two's complement binary representation, that is, if it
      * is equal to zero.
      *
      * @param i the value whose highest one bit is to be computed
      * @return an {@code int} value with a single one-bit, in the position
      *     of the highest-order one-bit in the specified value, or zero if
      *     the specified value is itself equal to zero.
      * @since 1.5
      */
     public static int highestOneBit(int i) {
-        // HD, Figure 3-1
-        i |= (i >>  1);
-        i |= (i >>  2);
-        i |= (i >>  4);
-        i |= (i >>  8);
-        i |= (i >> 16);
-        return i - (i >>> 1);
+        return i & (MIN_VALUE >>> numberOfLeadingZeros(i));
     }
 
     /**
      * Returns an {@code int} value with at most a single one-bit, in the
      * position of the lowest-order ("rightmost") one-bit in the specified
      * {@code int} value.  Returns zero if the specified value has no
      * one-bits in its two's complement binary representation, that is, if it
      * is equal to zero.
      *
      * @param i the value whose lowest one bit is to be computed
      * @return an {@code int} value with a single one-bit, in the position
      *     of the lowest-order one-bit in the specified value, or zero if
      *     the specified value is itself equal to zero.
      * @since 1.5
      */
     public static int lowestOneBit(int i) {
         // HD, Section 2-1
         return i & -i;
     }
 
     /**
      * Returns the number of zero bits preceding the highest-order
      * ("leftmost") one-bit in the two's complement binary representation
      * of the specified {@code int} value.  Returns 32 if the
      * specified value has no one-bits in its two's complement representation,
      * in other words if it is equal to zero.
      *
      * <p>Note that this method is closely related to the logarithm base 2.
      * For all positive {@code int} values x:
      * <ul>
      * <li>floor(log<sub>2</sub>(x)) = {@code 31 - numberOfLeadingZeros(x)}
      * <li>ceil(log<sub>2</sub>(x)) = {@code 32 - numberOfLeadingZeros(x - 1)}
      * </ul>
      *
      * @param i the value whose number of leading zeros is to be computed
      * @return the number of zero bits preceding the highest-order
      *     ("leftmost") one-bit in the two's complement binary representation
      *     of the specified {@code int} value, or 32 if the value
      *     is equal to zero.
      * @since 1.5
      */
+    @HotSpotIntrinsicCandidate
     public static int numberOfLeadingZeros(int i) {
-        // HD, Figure 5-6
-        if (i == 0)
-            return 32;
-        int n = 1;
-        if (i >>> 16 == 0) { n += 16; i <<= 16; }
-        if (i >>> 24 == 0) { n +=  8; i <<=  8; }
-        if (i >>> 28 == 0) { n +=  4; i <<=  4; }
-        if (i >>> 30 == 0) { n +=  2; i <<=  2; }
-        n -= i >>> 31;
-        return n;
+        // HD, Count leading 0's
+        if (i <= 0)
+            return i == 0 ? 32 : 0;
+        int n = 31;
+        if (i >= 1 << 16) { n -= 16; i >>>= 16; }
+        if (i >= 1 <<  8) { n -=  8; i >>>=  8; }
+        if (i >= 1 <<  4) { n -=  4; i >>>=  4; }
+        if (i >= 1 <<  2) { n -=  2; i >>>=  2; }
+        return n - (i >>> 1);
     }
 
     /**
      * Returns the number of zero bits following the lowest-order ("rightmost")
      * one-bit in the two's complement binary representation of the specified
      * {@code int} value.  Returns 32 if the specified value has no
      * one-bits in its two's complement representation, in other words if it is
      * equal to zero.
      *
      * @param i the value whose number of trailing zeros is to be computed
      * @return the number of zero bits following the lowest-order ("rightmost")
      *     one-bit in the two's complement binary representation of the
      *     specified {@code int} value, or 32 if the value is equal
      *     to zero.
      * @since 1.5
      */
+    @HotSpotIntrinsicCandidate
     public static int numberOfTrailingZeros(int i) {
-        // HD, Figure 5-14
-        int y;
-        if (i == 0) return 32;
-        int n = 31;
-        y = i <<16; if (y != 0) { n = n -16; i = y; }
-        y = i << 8; if (y != 0) { n = n - 8; i = y; }
-        y = i << 4; if (y != 0) { n = n - 4; i = y; }
-        y = i << 2; if (y != 0) { n = n - 2; i = y; }
-        return n - ((i << 1) >>> 31);
+        // HD, Count trailing 0's
+        i = ~i & (i - 1);
+        if (i <= 0) return i & 32;
+        int n = 1;
+        if (i > 1 << 16) { n += 16; i >>>= 16; }
+        if (i > 1 <<  8) { n +=  8; i >>>=  8; }
+        if (i > 1 <<  4) { n +=  4; i >>>=  4; }
+        if (i > 1 <<  2) { n +=  2; i >>>=  2; }
+        return n + (i >>> 1);
     }
 
     /**
      * Returns the number of one-bits in the two's complement binary
      * representation of the specified {@code int} value.  This function is
      * sometimes referred to as the <i>population count</i>.
      *
      * @param i the value whose bits are to be counted
      * @return the number of one-bits in the two's complement binary
      *     representation of the specified {@code int} value.
      * @since 1.5
      */
+    @HotSpotIntrinsicCandidate
     public static int bitCount(int i) {
         // HD, Figure 5-2
         i = i - ((i >>> 1) & 0x55555555);
         i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
         i = (i + (i >>> 4)) & 0x0f0f0f0f;
         i = i + (i >>> 8);
         i = i + (i >>> 16);
         return i & 0x3f;
     }
 
     /**
      * Returns the value obtained by rotating the two's complement binary
      * representation of the specified {@code int} value left by the
      * specified number of bits.  (Bits shifted out of the left hand, or
      * high-order, side reenter on the right, or low-order.)
      *
      * <p>Note that left rotation with a negative distance is equivalent to
      * right rotation: {@code rotateLeft(val, -distance) == rotateRight(val,
      * distance)}.  Note also that rotation by any multiple of 32 is a
      * no-op, so all but the last five bits of the rotation distance can be
      * ignored, even if the distance is negative: {@code rotateLeft(val,
      * distance) == rotateLeft(val, distance & 0x1F)}.
      *
      * @param i the value whose bits are to be rotated left
      * @param distance the number of bit positions to rotate left
      * @return the value obtained by rotating the two's complement binary
      *     representation of the specified {@code int} value left by the
      *     specified number of bits.
      * @since 1.5
      */
     public static int rotateLeft(int i, int distance) {
         return (i << distance) | (i >>> -distance);
     }
 
     /**
      * Returns the value obtained by rotating the two's complement binary
      * representation of the specified {@code int} value right by the
      * specified number of bits.  (Bits shifted out of the right hand, or
      * low-order, side reenter on the left, or high-order.)
      *
      * <p>Note that right rotation with a negative distance is equivalent to
      * left rotation: {@code rotateRight(val, -distance) == rotateLeft(val,
      * distance)}.  Note also that rotation by any multiple of 32 is a
      * no-op, so all but the last five bits of the rotation distance can be
      * ignored, even if the distance is negative: {@code rotateRight(val,
      * distance) == rotateRight(val, distance & 0x1F)}.
      *
      * @param i the value whose bits are to be rotated right
      * @param distance the number of bit positions to rotate right
      * @return the value obtained by rotating the two's complement binary
      *     representation of the specified {@code int} value right by the
      *     specified number of bits.
      * @since 1.5
      */
     public static int rotateRight(int i, int distance) {
         return (i >>> distance) | (i << -distance);
     }
 
     /**
      * Returns the value obtained by reversing the order of the bits in the
      * two's complement binary representation of the specified {@code int}
      * value.
      *
      * @param i the value to be reversed
      * @return the value obtained by reversing order of the bits in the
      *     specified {@code int} value.
      * @since 1.5
      */
     public static int reverse(int i) {
         // HD, Figure 7-1
         i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555;
         i = (i & 0x33333333) << 2 | (i >>> 2) & 0x33333333;
         i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f;
-        i = (i << 24) | ((i & 0xff00) << 8) |
-            ((i >>> 8) & 0xff00) | (i >>> 24);
-        return i;
+
+        return reverseBytes(i);
     }
 
     /**
      * Returns the signum function of the specified {@code int} value.  (The
      * return value is -1 if the specified value is negative; 0 if the
      * specified value is zero; and 1 if the specified value is positive.)
      *
      * @param i the value whose signum is to be computed
      * @return the signum function of the specified {@code int} value.
      * @since 1.5
      */
     public static int signum(int i) {
         // HD, Section 2-7
         return (i >> 31) | (-i >>> 31);
     }
 
     /**
      * Returns the value obtained by reversing the order of the bytes in the
      * two's complement representation of the specified {@code int} value.
      *
      * @param i the value whose bytes are to be reversed
      * @return the value obtained by reversing the bytes in the specified
      *     {@code int} value.
      * @since 1.5
      */
+    @HotSpotIntrinsicCandidate
     public static int reverseBytes(int i) {
-        return ((i >>> 24)           ) |
-               ((i >>   8) &   0xFF00) |
-               ((i <<   8) & 0xFF0000) |
-               ((i << 24));
+        return (i << 24)            |
+               ((i & 0xff00) << 8)  |
+               ((i >>> 8) & 0xff00) |
+               (i >>> 24);
     }
 
     /**
      * Adds two integers together as per the + operator.
      *
      * @param a the first operand
      * @param b the second operand
      * @return the sum of {@code a} and {@code b}
      * @see java.util.function.BinaryOperator
      * @since 1.8
      */
     public static int sum(int a, int b) {
         return a + b;
     }
 
     /**
      * Returns the greater of two {@code int} values
      * as if by calling {@link Math#max(int, int) Math.max}.
      *
      * @param a the first operand
      * @param b the second operand
      * @return the greater of {@code a} and {@code b}
      * @see java.util.function.BinaryOperator
      * @since 1.8
      */
     public static int max(int a, int b) {
         return Math.max(a, b);
     }
 
     /**
      * Returns the smaller of two {@code int} values
      * as if by calling {@link Math#min(int, int) Math.min}.
      *
      * @param a the first operand
      * @param b the second operand
      * @return the smaller of {@code a} and {@code b}
      * @see java.util.function.BinaryOperator
      * @since 1.8
      */
     public static int min(int a, int b) {
         return Math.min(a, b);
     }
 
+    /**
+     * Returns an {@link Optional} containing the nominal descriptor for this
+     * instance, which is the instance itself.
+     *
+     * @return an {@link Optional} describing the {@linkplain Integer} instance
+     * @since 12
+     */
+    @Override
+    public Optional<Integer> describeConstable() {
+        return Optional.of(this);
+    }
+
+    /**
+     * Resolves this instance as a {@link ConstantDesc}, the result of which is
+     * the instance itself.
+     *
+     * @param lookup ignored
+     * @return the {@linkplain Integer} instance
+     * @since 12
+     */
+    @Override
+    public Integer resolveConstantDesc(MethodHandles.Lookup lookup) {
+        return this;
+    }
+
     /** use serialVersionUID from JDK 1.0.2 for interoperability */
     @Native private static final long serialVersionUID = 1360826667806852920L;
 }