我的学习之路—String源码分析

小咪咪 2022-08-27 03:24 153阅读 0赞

String 源码

/*
 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */
 package java.lang;
 
 import java.io.ObjectStreamField;
 import java.io.UnsupportedEncodingException;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
 import java.util.Formatter;
 import java.util.Locale;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
 
 /**
 * The <code>String</code> class represents character strings. All
 * string literals in Java programs, such as <code>"abc"</code>, are
 * implemented as instances of this class.
 * 
 * Strings are constant; their values cannot be changed after they
 * are created. String buffers support mutable strings.
 * Because String objects are immutable they can be shared. For example:
 * <blockquote><pre>
 * String str = "abc";
 * </pre></blockquote>
 * is equivalent to:
 * <blockquote><pre>
 * char data[] = {'a', 'b', 'c'};
 * String str = new String(data);
 * </pre></blockquote>
 * Here are some more examples of how strings can be used:
 * <blockquote><pre>
 * System.out.println("abc");
 * String cde = "cde";
 * System.out.println("abc" + cde);
 * String c = "abc".substring(2,3);
 * String d = cde.substring(1, 2);
 * </pre></blockquote>
 * 
 * The class <code>String</code> includes methods for examining
 * individual characters of the sequence, for comparing strings, for
 * searching strings, for extracting substrings, and for creating a
 * copy of a string with all characters translated to uppercase or to
 * lowercase. Case mapping is based on the Unicode Standard version
 * specified by the {@link java.lang.Character Character} class.
 * 
 * The Java language provides special support for the string
 * concatenation operator ( + ), and for conversion of
 * other objects to strings. String concatenation is implemented
 * through the <code>StringBuilder</code>(or <code>StringBuffer</code>)
 * class and its <code>append</code> method.
 * String conversions are implemented through the method
 * <code>toString</code>, defined by <code>Object</code> and
 * inherited by all classes in Java. For additional information on
 * string concatenation and conversion, see Gosling, Joy, and Steele,
 * The Java Language Specification.
 *
 * Unless otherwise noted, passing a <tt>null</tt> argument to a constructor
 * or method in this class will cause a {@link NullPointerException} to be
 * thrown.
 *
 * A <code>String</code> represents a string in the UTF-16 format
 * in which supplementary characters are represented by surrogate
 * pairs (see the section <a href="Character.html#unicode">Unicode
 * Character Representations</a> in the <code>Character</code> class for
 * more information).
 * Index values refer to <code>char</code> code units, so a supplementary
 * character uses two positions in a <code>String</code>.
 * The <code>String</code> class provides methods for dealing with
 * Unicode code points (i.e., characters), in addition to those for
 * dealing with Unicode code units (i.e., <code>char</code> values).
 *
 * @author Lee Boynton
 * @author Arthur van Hoff
 * @author Martin Buchholz
 * @author Ulf Zibis
 * @see java.lang.Object#toString()
 * @see java.lang.StringBuffer
 * @see java.lang.StringBuilder
 * @see java.nio.charset.Charset
 * @since JDK1.0
 */
 
 public final class String
 implements java.io.Serializable, Comparable<String>, CharSequence {
 /** The value is used for character storage. */
 private final char value[];
 
 /** Cache the hash code for the string */
 private int hash; // Default to 0
 
 /** use serialVersionUID from JDK 1.0.2 for interoperability */
 private static final long serialVersionUID = -6849794470754667710L;
 
 /**
 * Class String is special cased within the Serialization Stream Protocol.
 *
 * A String instance is written initially into an ObjectOutputStream in the
 * following format:
 * <pre>
 * <code>TC_STRING</code> (utf String)
 * </pre>
 * The String is written by method <code>DataOutput.writeUTF</code>.
 * A new handle is generated to refer to all future references to the
 * string instance within the stream.
 */
 private static final ObjectStreamField[] serialPersistentFields =
 new ObjectStreamField[0];
 
 /**
 * Initializes a newly created {@code String} object so that it represents
 * an empty character sequence. Note that use of this constructor is
 * unnecessary since Strings are immutable.
 */
 public String() {
 this.value = new char[0];
 }
 
 /**
 * Initializes a newly created {@code String} object so that it represents
 * the same sequence of characters as the argument; in other words, the
 * newly created string is a copy of the argument string. Unless an
 * explicit copy of {@code original} is needed, use of this constructor is
 * unnecessary since Strings are immutable.
 *
 * @param original
 * A {@code String}
 */
 public String(String original) {
 this.value = original.value;
 this.hash = original.hash;
 }
 
 /**
 * Allocates a new {@code String} so that it represents the sequence of
 * characters currently contained in the character array argument. The
 * contents of the character array are copied; subsequent modification of
 * the character array does not affect the newly created string.
 *
 * @param value
 * The initial value of the string
 */
 public String(char value[]) {
 this.value = Arrays.copyOf(value, value.length);
 }
 
 /**
 * Allocates a new {@code String} that contains characters from a subarray
 * of the character array argument. The {@code offset} argument is the
 * index of the first character of the subarray and the {@code count}
 * argument specifies the length of the subarray. The contents of the
 * subarray are copied; subsequent modification of the character array does
 * not affect the newly created string.
 *
 * @param value
 * Array that is the source of characters
 *
 * @param offset
 * The initial offset
 *
 * @param count
 * The length
 *
 * @throws IndexOutOfBoundsException
 * If the {@code offset} and {@code count} arguments index
 * characters outside the bounds of the {@code value} array
 */
 public String(char value[], int offset, int count) {
 if (offset < 0) {
 throw new StringIndexOutOfBoundsException(offset);
 }
 if (count < 0) {
 throw new StringIndexOutOfBoundsException(count);
 }
 // Note: offset or count might be near -1>>>1.
 if (offset > value.length - count) {
 throw new StringIndexOutOfBoundsException(offset + count);
 }
 this.value = Arrays.copyOfRange(value, offset, offset+count);
 }
 
 /**
 * Allocates a new {@code String} that contains characters from a subarray
 * of the <a href="Character.html#unicode">Unicode code point</a> array
 * argument. The {@code offset} argument is the index of the first code
 * point of the subarray and the {@code count} argument specifies the
 * length of the subarray. The contents of the subarray are converted to
 * {@code char}s; subsequent modification of the {@code int} array does not
 * affect the newly created string.
 *
 * @param codePoints
 * Array that is the source of Unicode code points
 *
 * @param offset
 * The initial offset
 *
 * @param count
 * The length
 *
 * @throws IllegalArgumentException
 * If any invalid Unicode code point is found in {@code
 * codePoints}
 *
 * @throws IndexOutOfBoundsException
 * If the {@code offset} and {@code count} arguments index
 * characters outside the bounds of the {@code codePoints} array
 *
 * @since 1.5
 */
 public String(int[] codePoints, int offset, int count) {
 if (offset < 0) {
 throw new StringIndexOutOfBoundsException(offset);
 }
 if (count < 0) {
 throw new StringIndexOutOfBoundsException(count);
 }
 // Note: offset or count might be near -1>>>1.
 if (offset > codePoints.length - count) {
 throw new StringIndexOutOfBoundsException(offset + count);
 }
 
 final int end = offset + count;
 
 // Pass 1: Compute precise size of char[]
 int n = count;
 for (int i = offset; i < end; i++) {
 int c = codePoints[i];
 if (Character.isBmpCodePoint(c))
 continue;
 else if (Character.isValidCodePoint(c))
 n++;
 else throw new IllegalArgumentException(Integer.toString(c));
 }
 
 // Pass 2: Allocate and fill in char[]
 final char[] v = new char[n];
 
 for (int i = offset, j = 0; i < end; i++, j++) {
 int c = codePoints[i];
 if (Character.isBmpCodePoint(c))
 v[j] = (char)c;
 else
 Character.toSurrogates(c, v, j++);
 }
 
 this.value = v;
 }
 
 /**
 * Allocates a new {@code String} constructed from a subarray of an array
 * of 8-bit integer values.
 *
 * The {@code offset} argument is the index of the first byte of the
 * subarray, and the {@code count} argument specifies the length of the
 * subarray.
 *
 * Each {@code byte} in the subarray is converted to a {@code char} as
 * specified in the method above.
 *
 * @deprecated This method does not properly convert bytes into characters.
 * As of JDK 1.1, the preferred way to do this is via the
 * {@code String} constructors that take a {@link
 * java.nio.charset.Charset}, charset name, or that use the platform's
 * default charset.
 *
 * @param ascii
 * The bytes to be converted to characters
 *
 * @param hibyte
 * The top 8 bits of each 16-bit Unicode code unit
 *
 * @param offset
 * The initial offset
 * @param count
 * The length
 *
 * @throws IndexOutOfBoundsException
 * If the {@code offset} or {@code count} argument is invalid
 *
 * @see #String(byte[], int)
 * @see #String(byte[], int, int, java.lang.String)
 * @see #String(byte[], int, int, java.nio.charset.Charset)
 * @see #String(byte[], int, int)
 * @see #String(byte[], java.lang.String)
 * @see #String(byte[], java.nio.charset.Charset)
 * @see #String(byte[])
 */
 @Deprecated
 public String(byte ascii[], int hibyte, int offset, int count) {
 checkBounds(ascii, offset, count);
 char value[] = new char[count];
 
 if (hibyte == 0) {
 for (int i = count; i-- > 0;) {
 value[i] = (char)(ascii[i + offset] & 0xff);
 }
 } else {
 hibyte <<= 8;
 for (int i = count; i-- > 0;) {
 value[i] = (char)(hibyte | (ascii[i + offset] & 0xff));
 }
 }
 this.value = value;
 }
 
 /**
 * Allocates a new {@code String} containing characters constructed from
 * an array of 8-bit integer values. Each character cin the
 * resulting string is constructed from the corresponding component
 * b in the byte array such that:
 *
 * <blockquote><pre>
 * c == (char)(((hibyte & 0xff) << 8)
 * | (b & 0xff))
 * </pre></blockquote>
 *
 * @deprecated This method does not properly convert bytes into
 * characters. As of JDK 1.1, the preferred way to do this is via the
 * {@code String} constructors that take a {@link
 * java.nio.charset.Charset}, charset name, or that use the platform's
 * default charset.
 *
 * @param ascii
 * The bytes to be converted to characters
 *
 * @param hibyte
 * The top 8 bits of each 16-bit Unicode code unit
 *
 * @see #String(byte[], int, int, java.lang.String)
 * @see #String(byte[], int, int, java.nio.charset.Charset)
 * @see #String(byte[], int, int)
 * @see #String(byte[], java.lang.String)
 * @see #String(byte[], java.nio.charset.Charset)
 * @see #String(byte[])
 */
 @Deprecated
 public String(byte ascii[], int hibyte) {
 this(ascii, hibyte, 0, ascii.length);
 }
 
 /* Common private utility method used to bounds check the byte array
 * and requested offset & length values used by the String(byte[],..)
 * constructors.
 */
 private static void checkBounds(byte[] bytes, int offset, int length) {
 if (length < 0)
 throw new StringIndexOutOfBoundsException(length);
 if (offset < 0)
 throw new StringIndexOutOfBoundsException(offset);
 if (offset > bytes.length - length)
 throw new StringIndexOutOfBoundsException(offset + length);
 }
 
 /**
 * Constructs a new {@code String} by decoding the specified subarray of
 * bytes using the specified charset. The length of the new {@code String}
 * is a function of the charset, and hence may not be equal to the length
 * of the subarray.
 *
 * The behavior of this constructor when the given bytes are not valid
 * in the given charset is unspecified. The {@link
 * java.nio.charset.CharsetDecoder} class should be used when more control
 * over the decoding process is required.
 *
 * @param bytes
 * The bytes to be decoded into characters
 *
 * @param offset
 * The index of the first byte to decode
 *
 * @param length
 * The number of bytes to decode
 
 * @param charsetName
 * The name of a supported {@linkplain java.nio.charset.Charset
 * charset}
 *
 * @throws UnsupportedEncodingException
 * If the named charset is not supported
 *
 * @throws IndexOutOfBoundsException
 * If the {@code offset} and {@code length} arguments index
 * characters outside the bounds of the {@code bytes} array
 *
 * @since JDK1.1
 */
 public String(byte bytes[], int offset, int length, String charsetName)
 throws UnsupportedEncodingException {
 if (charsetName == null)
 throw new NullPointerException("charsetName");
 checkBounds(bytes, offset, length);
 this.value = StringCoding.decode(charsetName, bytes, offset, length);
 }
 
 /**
 * Constructs a new {@code String} by decoding the specified subarray of
 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
 * The length of the new {@code String} is a function of the charset, and
 * hence may not be equal to the length of the subarray.
 *
 * This method always replaces malformed-input and unmappable-character
 * sequences with this charset's default replacement string. The {@link
 * java.nio.charset.CharsetDecoder} class should be used when more control
 * over the decoding process is required.
 *
 * @param bytes
 * The bytes to be decoded into characters
 *
 * @param offset
 * The index of the first byte to decode
 *
 * @param length
 * The number of bytes to decode
 *
 * @param charset
 * The {@linkplain java.nio.charset.Charset charset} to be used to
 * decode the {@code bytes}
 *
 * @throws IndexOutOfBoundsException
 * If the {@code offset} and {@code length} arguments index
 * characters outside the bounds of the {@code bytes} array
 *
 * @since 1.6
 */
 public String(byte bytes[], int offset, int length, Charset charset) {
 if (charset == null)
 throw new NullPointerException("charset");
 checkBounds(bytes, offset, length);
 this.value = StringCoding.decode(charset, bytes, offset, length);
 }
 
 /**
 * Constructs a new {@code String} by decoding the specified array of bytes
 * using the specified {@linkplain java.nio.charset.Charset charset}. The
 * length of the new {@code String} is a function of the charset, and hence
 * may not be equal to the length of the byte array.
 *
 * The behavior of this constructor when the given bytes are not valid
 * in the given charset is unspecified. The {@link
 * java.nio.charset.CharsetDecoder} class should be used when more control
 * over the decoding process is required.
 *
 * @param bytes
 * The bytes to be decoded into characters
 *
 * @param charsetName
 * The name of a supported {@linkplain java.nio.charset.Charset
 * charset}
 *
 * @throws UnsupportedEncodingException
 * If the named charset is not supported
 *
 * @since JDK1.1
 */
 public String(byte bytes[], String charsetName)
 throws UnsupportedEncodingException {
 this(bytes, 0, bytes.length, charsetName);
 }
 
 /**
 * Constructs a new {@code String} by decoding the specified array of
 * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
 * The length of the new {@code String} is a function of the charset, and
 * hence may not be equal to the length of the byte array.
 *
 * This method always replaces malformed-input and unmappable-character
 * sequences with this charset's default replacement string. The {@link
 * java.nio.charset.CharsetDecoder} class should be used when more control
 * over the decoding process is required.
 *
 * @param bytes
 * The bytes to be decoded into characters
 *
 * @param charset
 * The {@linkplain java.nio.charset.Charset charset} to be used to
 * decode the {@code bytes}
 *
 * @since 1.6
 */
 public String(byte bytes[], Charset charset) {
 this(bytes, 0, bytes.length, charset);
 }
 
 /**
 * Constructs a new {@code String} by decoding the specified subarray of
 * bytes using the platform's default charset. The length of the new
 * {@code String} is a function of the charset, and hence may not be equal
 * to the length of the subarray.
 *
 * The behavior of this constructor when the given bytes are not valid
 * in the default charset is unspecified. The {@link
 * java.nio.charset.CharsetDecoder} class should be used when more control
 * over the decoding process is required.
 *
 * @param bytes
 * The bytes to be decoded into characters
 *
 * @param offset
 * The index of the first byte to decode
 *
 * @param length
 * The number of bytes to decode
 *
 * @throws IndexOutOfBoundsException
 * If the {@code offset} and the {@code length} arguments index
 * characters outside the bounds of the {@code bytes} array
 *
 * @since JDK1.1
 */
 public String(byte bytes[], int offset, int length) {
 checkBounds(bytes, offset, length);
 this.value = StringCoding.decode(bytes, offset, length);
 }
 
 /**
 * Constructs a new {@code String} by decoding the specified array of bytes
 * using the platform's default charset. The length of the new {@code
 * String} is a function of the charset, and hence may not be equal to the
 * length of the byte array.
 *
 * The behavior of this constructor when the given bytes are not valid
 * in the default charset is unspecified. The {@link
 * java.nio.charset.CharsetDecoder} class should be used when more control
 * over the decoding process is required.
 *
 * @param bytes
 * The bytes to be decoded into characters
 *
 * @since JDK1.1
 */
 public String(byte bytes[]) {
 this(bytes, 0, bytes.length);
 }
 
 /**
 * Allocates a new string that contains the sequence of characters
 * currently contained in the string buffer argument. The contents of the
 * string buffer are copied; subsequent modification of the string buffer
 * does not affect the newly created string.
 *
 * @param buffer
 * A {@code StringBuffer}
 */
 public String(StringBuffer buffer) {
 synchronized(buffer) {
 this.value = Arrays.copyOf(buffer.getValue(), buffer.length());
 }
 }
 
 /**
 * Allocates a new string that contains the sequence of characters
 * currently contained in the string builder argument. The contents of the
 * string builder are copied; subsequent modification of the string builder
 * does not affect the newly created string.
 *
 * This constructor is provided to ease migration to {@code
 * StringBuilder}. Obtaining a string from a string builder via the {@code
 * toString} method is likely to run faster and is generally preferred.
 *
 * @param builder
 * A {@code StringBuilder}
 *
 * @since 1.5
 */
 public String(StringBuilder builder) {
 this.value = Arrays.copyOf(builder.getValue(), builder.length());
 }
 
 /*
 * Package private constructor which shares value array for speed.
 * this constructor is always expected to be called with share==true.
 * a separate constructor is needed because we already have a public
 * String(char[]) constructor that makes a copy of the given char[].
 */
 String(char[] value, boolean share) {
 // assert share : "unshared not supported";
 this.value = value;
 }
 
 /**
 * Package private constructor
 *
 * @deprecated Use {@link #String(char[],int,int)} instead.
 */
 @Deprecated
 String(int offset, int count, char[] value) {
 this(value, offset, count);
 }
 
 /**
 * Returns the length of this string.
 * The length is equal to the number of <a href="Character.html#unicode">Unicode
 * code units</a> in the string.
 *
 * @return the length of the sequence of characters represented by this
 * object.
 */
 public int length() {
 return value.length;
 }
 
 /**
 * Returns <tt>true</tt> if, and only if, {@link #length()} is <tt>0</tt>.
 *
 * @return <tt>true</tt> if {@link #length()} is <tt>0</tt>, otherwise
 * <tt>false</tt>
 *
 * @since 1.6
 */
 public boolean isEmpty() {
 return value.length == 0;
 }
 
 /**
 * Returns the <code>char</code> value at the
 * specified index. An index ranges from <code>0</code> to
 * <code>length() - 1</code>. The first <code>char</code> value of the sequence
 * is at index <code>0</code>, the next at index <code>1</code>,
 * and so on, as for array indexing.
 *
 * If the <code>char</code> value specified by the index is a
 * <a href="Character.html#unicode">surrogate</a>, the surrogate
 * value is returned.
 *
 * @param index the index of the <code>char</code> value.
 * @return the <code>char</code> value at the specified index of this string.
 * The first <code>char</code> value is at index <code>0</code>.
 * @exception IndexOutOfBoundsException if the <code>index</code>
 * argument is negative or not less than the length of this
 * string.
 */
 public char charAt(int index) {
 if ((index < 0) || (index >= value.length)) {
 throw new StringIndexOutOfBoundsException(index);
 }
 return value[index];
 }
 
 /**
 * Returns the character (Unicode code point) at the specified
 * index. The index refers to <code>char</code> values
 * (Unicode code units) and ranges from <code>0</code> to
 * {@link #length()}<code> - 1</code>.
 *
 * If the <code>char</code> value specified at the given index
 * is in the high-surrogate range, the following index is less
 * than the length of this <code>String</code>, and the
 * <code>char</code> value at the following index is in the
 * low-surrogate range, then the supplementary code point
 * corresponding to this surrogate pair is returned. Otherwise,
 * the <code>char</code> value at the given index is returned.
 *
 * @param index the index to the <code>char</code> values
 * @return the code point value of the character at the
 * <code>index</code>
 * @exception IndexOutOfBoundsException if the <code>index</code>
 * argument is negative or not less than the length of this
 * string.
 * @since 1.5
 */
 public int codePointAt(int index) {
 if ((index < 0) || (index >= value.length)) {
 throw new StringIndexOutOfBoundsException(index);
 }
 return Character.codePointAtImpl(value, index, value.length);
 }
 
 /**
 * Returns the character (Unicode code point) before the specified
 * index. The index refers to <code>char</code> values
 * (Unicode code units) and ranges from <code>1</code> to {@link
 * CharSequence#length() length}.
 *
 * If the <code>char</code> value at <code>(index - 1)</code>
 * is in the low-surrogate range, <code>(index - 2)</code> is not
 * negative, and the <code>char</code> value at <code>(index -
 * 2)</code> is in the high-surrogate range, then the
 * supplementary code point value of the surrogate pair is
 * returned. If the <code>char</code> value at <code>index -
 * 1</code> is an unpaired low-surrogate or a high-surrogate, the
 * surrogate value is returned.
 *
 * @param index the index following the code point that should be returned
 * @return the Unicode code point value before the given index.
 * @exception IndexOutOfBoundsException if the <code>index</code>
 * argument is less than 1 or greater than the length
 * of this string.
 * @since 1.5
 */
 public int codePointBefore(int index) {
 int i = index - 1;
 if ((i < 0) || (i >= value.length)) {
 throw new StringIndexOutOfBoundsException(index);
 }
 return Character.codePointBeforeImpl(value, index, 0);
 }
 
 /**
 * Returns the number of Unicode code points in the specified text
 * range of this <code>String</code>. The text range begins at the
 * specified <code>beginIndex</code> and extends to the
 * <code>char</code> at index <code>endIndex - 1</code>. Thus the
 * length (in <code>char</code>s) of the text range is
 * <code>endIndex-beginIndex</code>. Unpaired surrogates within
 * the text range count as one code point each.
 *
 * @param beginIndex the index to the first <code>char</code> of
 * the text range.
 * @param endIndex the index after the last <code>char</code> of
 * the text range.
 * @return the number of Unicode code points in the specified text
 * range
 * @exception IndexOutOfBoundsException if the
 * <code>beginIndex</code> is negative, or <code>endIndex</code>
 * is larger than the length of this <code>String</code>, or
 * <code>beginIndex</code> is larger than <code>endIndex</code>.
 * @since 1.5
 */
 public int codePointCount(int beginIndex, int endIndex) {
 if (beginIndex < 0 || endIndex > value.length || beginIndex > endIndex) {
 throw new IndexOutOfBoundsException();
 }
 return Character.codePointCountImpl(value, beginIndex, endIndex - beginIndex);
 }
 
 /**
 * Returns the index within this <code>String</code> that is
 * offset from the given <code>index</code> by
 * <code>codePointOffset</code> code points. Unpaired surrogates
 * within the text range given by <code>index</code> and
 * <code>codePointOffset</code> count as one code point each.
 *
 * @param index the index to be offset
 * @param codePointOffset the offset in code points
 * @return the index within this <code>String</code>
 * @exception IndexOutOfBoundsException if <code>index</code>
 * is negative or larger then the length of this
 * <code>String</code>, or if <code>codePointOffset</code> is positive
 * and the substring starting with <code>index</code> has fewer
 * than <code>codePointOffset</code> code points,
 * or if <code>codePointOffset</code> is negative and the substring
 * before <code>index</code> has fewer than the absolute value
 * of <code>codePointOffset</code> code points.
 * @since 1.5
 */
 public int offsetByCodePoints(int index, int codePointOffset) {
 if (index < 0 || index > value.length) {
 throw new IndexOutOfBoundsException();
 }
 return Character.offsetByCodePointsImpl(value, 0, value.length,
 index, codePointOffset);
 }
 
 /**
 * Copy characters from this string into dst starting at dstBegin.
 * This method doesn't perform any range checking.
 */
 void getChars(char dst[], int dstBegin) {
 System.arraycopy(value, 0, dst, dstBegin, value.length);
 }
 
 /**
 * Copies characters from this string into the destination character
 * array.
 * 
 * The first character to be copied is at index <code>srcBegin</code>;
 * the last character to be copied is at index <code>srcEnd-1</code>
 * (thus the total number of characters to be copied is
 * <code>srcEnd-srcBegin</code>). The characters are copied into the
 * subarray of <code>dst</code> starting at index <code>dstBegin</code>
 * and ending at index:
 * <blockquote><pre>
 * dstbegin + (srcEnd-srcBegin) - 1
 * </pre></blockquote>
 *
 * @param srcBegin index of the first character in the string
 * to copy.
 * @param srcEnd index after the last character in the string
 * to copy.
 * @param dst the destination array.
 * @param dstBegin the start offset in the destination array.
 * @exception IndexOutOfBoundsException If any of the following
 * is true:
 * <ul><li><code>srcBegin</code> is negative.
 * <li><code>srcBegin</code> is greater than <code>srcEnd</code>
 * <li><code>srcEnd</code> is greater than the length of this
 * string
 * <li><code>dstBegin</code> is negative
 * <li><code>dstBegin+(srcEnd-srcBegin)</code> is larger than
 * <code>dst.length</code></ul>
 */
 public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) {
 if (srcBegin < 0) {
 throw new StringIndexOutOfBoundsException(srcBegin);
 }
 if (srcEnd > value.length) {
 throw new StringIndexOutOfBoundsException(srcEnd);
 }
 if (srcBegin > srcEnd) {
 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
 }
 System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin);
 }
 
 /**
 * Copies characters from this string into the destination byte array. Each
 * byte receives the 8 low-order bits of the corresponding character. The
 * eight high-order bits of each character are not copied and do not
 * participate in the transfer in any way.
 *
 * The first character to be copied is at index {@code srcBegin}; the
 * last character to be copied is at index {@code srcEnd-1}. The total
 * number of characters to be copied is {@code srcEnd-srcBegin}. The
 * characters, converted to bytes, are copied into the subarray of {@code
 * dst} starting at index {@code dstBegin} and ending at index:
 *
 * <blockquote><pre>
 * dstbegin + (srcEnd-srcBegin) - 1
 * </pre></blockquote>
 *
 * @deprecated This method does not properly convert characters into
 * bytes. As of JDK 1.1, the preferred way to do this is via the
 * {@link #getBytes()} method, which uses the platform's default charset.
 *
 * @param srcBegin
 * Index of the first character in the string to copy
 *
 * @param srcEnd
 * Index after the last character in the string to copy
 *
 * @param dst
 * The destination array
 *
 * @param dstBegin
 * The start offset in the destination array
 *
 * @throws IndexOutOfBoundsException
 * If any of the following is true:
 * <ul>
 * <li> {@code srcBegin} is negative
 * <li> {@code srcBegin} is greater than {@code srcEnd}
 * <li> {@code srcEnd} is greater than the length of this String
 * <li> {@code dstBegin} is negative
 * <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code
 * dst.length}
 * </ul>
 */
 @Deprecated
 public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
 if (srcBegin < 0) {
 throw new StringIndexOutOfBoundsException(srcBegin);
 }
 if (srcEnd > value.length) {
 throw new StringIndexOutOfBoundsException(srcEnd);
 }
 if (srcBegin > srcEnd) {
 throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
 }
 int j = dstBegin;
 int n = srcEnd;
 int i = srcBegin;
 char[] val = value; /* avoid getfield opcode */
 
 while (i < n) {
 dst[j++] = (byte)val[i++];
 }
 }
 
 /**
 * Encodes this {@code String} into a sequence of bytes using the named
 * charset, storing the result into a new byte array.
 *
 * The behavior of this method when this string cannot be encoded in
 * the given charset is unspecified. The {@link
 * java.nio.charset.CharsetEncoder} class should be used when more control
 * over the encoding process is required.
 *
 * @param charsetName
 * The name of a supported {@linkplain java.nio.charset.Charset
 * charset}
 *
 * @return The resultant byte array
 *
 * @throws UnsupportedEncodingException
 * If the named charset is not supported
 *
 * @since JDK1.1
 */
 public byte[] getBytes(String charsetName)
 throws UnsupportedEncodingException {
 if (charsetName == null) throw new NullPointerException();
 return StringCoding.encode(charsetName, value, 0, value.length);
 }
 
 /**
 * Encodes this {@code String} into a sequence of bytes using the given
 * {@linkplain java.nio.charset.Charset charset}, storing the result into a
 * new byte array.
 *
 * This method always replaces malformed-input and unmappable-character
 * sequences with this charset's default replacement byte array. The
 * {@link java.nio.charset.CharsetEncoder} class should be used when more
 * control over the encoding process is required.
 *
 * @param charset
 * The {@linkplain java.nio.charset.Charset} to be used to encode
 * the {@code String}
 *
 * @return The resultant byte array
 *
 * @since 1.6
 */
 public byte[] getBytes(Charset charset) {
 if (charset == null) throw new NullPointerException();
 return StringCoding.encode(charset, value, 0, value.length);
 }
 
 /**
 * Encodes this {@code String} into a sequence of bytes using the
 * platform's default charset, storing the result into a new byte array.
 *
 * The behavior of this method when this string cannot be encoded in
 * the default charset is unspecified. The {@link
 * java.nio.charset.CharsetEncoder} class should be used when more control
 * over the encoding process is required.
 *
 * @return The resultant byte array
 *
 * @since JDK1.1
 */
 public byte[] getBytes() {
 return StringCoding.encode(value, 0, value.length);
 }
 
 /**
 * Compares this string to the specified object. The result is {@code
 * true} if and only if the argument is not {@code null} and is a {@code
 * String} object that represents the same sequence of characters as this
 * object.
 *
 * @param anObject
 * The object to compare this {@code String} against
 *
 * @return {@code true} if the given object represents a {@code String}
 * equivalent to this string, {@code false} otherwise
 *
 * @see #compareTo(String)
 * @see #equalsIgnoreCase(String)
 */
 public boolean equals(Object anObject) {
 if (this == anObject) {
 return true;
 }
 if (anObject instanceof String) {
 String anotherString = (String) anObject;
 int n = value.length;
 if (n == anotherString.value.length) {
 char v1[] = value;
 char v2[] = anotherString.value;
 int i = 0;
 while (n-- != 0) {
 if (v1[i] != v2[i])
 return false;
 i++;
 }
 return true;
 }
 }
 return false;
 }
 
 /**
 * Compares this string to the specified {@code StringBuffer}. The result
 * is {@code true} if and only if this {@code String} represents the same
 * sequence of characters as the specified {@code StringBuffer}.
 *
 * @param sb
 * The {@code StringBuffer} to compare this {@code String} against
 *
 * @return {@code true} if this {@code String} represents the same
 * sequence of characters as the specified {@code StringBuffer},
 * {@code false} otherwise
 *
 * @since 1.4
 */
 public boolean contentEquals(StringBuffer sb) {
 synchronized (sb) {
 return contentEquals((CharSequence) sb);
 }
 }
 
 /**
 * Compares this string to the specified {@code CharSequence}. The result
 * is {@code true} if and only if this {@code String} represents the same
 * sequence of char values as the specified sequence.
 *
 * @param cs
 * The sequence to compare this {@code String} against
 *
 * @return {@code true} if this {@code String} represents the same
 * sequence of char values as the specified sequence, {@code
 * false} otherwise
 *
 * @since 1.5
 */
 public boolean contentEquals(CharSequence cs) {
 if (value.length != cs.length())
 return false;
 // Argument is a StringBuffer, StringBuilder
 if (cs instanceof AbstractStringBuilder) {
 char v1[] = value;
 char v2[] = ((AbstractStringBuilder) cs).getValue();
 int i = 0;
 int n = value.length;
 while (n-- != 0) {
 if (v1[i] != v2[i])
 return false;
 i++;
 }
 return true;
 }
 // Argument is a String
 if (cs.equals(this))
 return true;
 // Argument is a generic CharSequence
 char v1[] = value;
 int i = 0;
 int n = value.length;
 while (n-- != 0) {
 if (v1[i] != cs.charAt(i))
 return false;
 i++;
 }
 return true;
 }
 
 /**
 * Compares this {@code String} to another {@code String}, ignoring case
 * considerations. Two strings are considered equal ignoring case if they
 * are of the same length and corresponding characters in the two strings
 * are equal ignoring case.
 *
 * Two characters {@code c1} and {@code c2} are considered the same
 * ignoring case if at least one of the following is true:
 * <ul>
 * <li> The two characters are the same (as compared by the
 * {@code ==} operator)
 * <li> Applying the method {@link
 * java.lang.Character#toUpperCase(char)} to each character
 * produces the same result
 * <li> Applying the method {@link
 * java.lang.Character#toLowerCase(char)} to each character
 * produces the same result
 * </ul>
 *
 * @param anotherString
 * The {@code String} to compare this {@code String} against
 *
 * @return {@code true} if the argument is not {@code null} and it
 * represents an equivalent {@code String} ignoring case; {@code
 * false} otherwise
 *
 * @see #equals(Object)
 */
 public boolean equalsIgnoreCase(String anotherString) {
 return (this == anotherString) ? true
 : (anotherString != null)
 && (anotherString.value.length == value.length)
 && regionMatches(true, 0, anotherString, 0, value.length);
 }
 
 /**
 * Compares two strings lexicographically.
 * The comparison is based on the Unicode value of each character in
 * the strings. The character sequence represented by this
 * <code>String</code> object is compared lexicographically to the
 * character sequence represented by the argument string. The result is
 * a negative integer if this <code>String</code> object
 * lexicographically precedes the argument string. The result is a
 * positive integer if this <code>String</code> object lexicographically
 * follows the argument string. The result is zero if the strings
 * are equal; <code>compareTo</code> returns <code>0</code> exactly when
 * the {@link #equals(Object)} method would return <code>true</code>.
 * 
 * This is the definition of lexicographic ordering. If two strings are
 * different, then either they have different characters at some index
 * that is a valid index for both strings, or their lengths are different,
 * or both. If they have different characters at one or more index
 * positions, let k be the smallest such index; then the string
 * whose character at position k has the smaller value, as
 * determined by using the < operator, lexicographically precedes the
 * other string. In this case, <code>compareTo</code> returns the
 * difference of the two character values at position <code>k</code> in
 * the two string -- that is, the value:
 * <blockquote><pre>
 * this.charAt(k)-anotherString.charAt(k)
 * </pre></blockquote>
 * If there is no index position at which they differ, then the shorter
 * string lexicographically precedes the longer string. In this case,
 * <code>compareTo</code> returns the difference of the lengths of the
 * strings -- that is, the value:
 * <blockquote><pre>
 * this.length()-anotherString.length()
 * </pre></blockquote>
 *
 * @param anotherString the <code>String</code> to be compared.
 * @return the value <code>0</code> if the argument string is equal to
 * this string; a value less than <code>0</code> if this string
 * is lexicographically less than the string argument; and a
 * value greater than <code>0</code> if this string is
 * lexicographically greater than the string argument.
 */
 public int compareTo(String anotherString) {
 int len1 = value.length;
 int len2 = anotherString.value.length;
 int lim = Math.min(len1, len2);
 char v1[] = value;
 char v2[] = anotherString.value;
 
 int k = 0;
 while (k < lim) {
 char c1 = v1[k];
 char c2 = v2[k];
 if (c1 != c2) {
 return c1 - c2;
 }
 k++;
 }
 return len1 - len2;
 }
 
 /**
 * A Comparator that orders <code>String</code> objects as by
 * <code>compareToIgnoreCase</code>. This comparator is serializable.
 * 
 * Note that this Comparator does not take locale into account,
 * and will result in an unsatisfactory ordering for certain locales.
 * The java.text package provides Collators to allow
 * locale-sensitive ordering.
 *
 * @see java.text.Collator#compare(String, String)
 * @since 1.2
 */
 public static final Comparator<String> CASE_INSENSITIVE_ORDER
 = new CaseInsensitiveComparator();
 private static class CaseInsensitiveComparator
 implements Comparator<String>, java.io.Serializable {
 // use serialVersionUID from JDK 1.2.2 for interoperability
 private static final long serialVersionUID = 8575799808933029326L;
 
 public int compare(String s1, String s2) {
 int n1 = s1.length();
 int n2 = s2.length();
 int min = Math.min(n1, n2);
 for (int i = 0; i < min; i++) {
 char c1 = s1.charAt(i);
 char c2 = s2.charAt(i);
 if (c1 != c2) {
 c1 = Character.toUpperCase(c1);
 c2 = Character.toUpperCase(c2);
 if (c1 != c2) {
 c1 = Character.toLowerCase(c1);
 c2 = Character.toLowerCase(c2);
 if (c1 != c2) {
 // No overflow because of numeric promotion
 return c1 - c2;
 }
 }
 }
 }
 return n1 - n2;
 }
 }
 
 /**
 * Compares two strings lexicographically, ignoring case
 * differences. This method returns an integer whose sign is that of
 * calling <code>compareTo</code> with normalized versions of the strings
 * where case differences have been eliminated by calling
 * <code>Character.toLowerCase(Character.toUpperCase(character))</code> on
 * each character.
 * 
 * Note that this method does not take locale into account,
 * and will result in an unsatisfactory ordering for certain locales.
 * The java.text package provides collators to allow
 * locale-sensitive ordering.
 *
 * @param str the <code>String</code> to be compared.
 * @return a negative integer, zero, or a positive integer as the
 * specified String is greater than, equal to, or less
 * than this String, ignoring case considerations.
 * @see java.text.Collator#compare(String, String)
 * @since 1.2
 */
 public int compareToIgnoreCase(String str) {
 return CASE_INSENSITIVE_ORDER.compare(this, str);
 }
 
 /**
 * Tests if two string regions are equal.
 * 
 * A substring of this <tt>String</tt> object is compared to a substring
 * of the argument other. The result is true if these substrings
 * represent identical character sequences. The substring of this
 * <tt>String</tt> object to be compared begins at index <tt>toffset</tt>
 * and has length <tt>len</tt>. The substring of other to be compared
 * begins at index <tt>ooffset</tt> and has length <tt>len</tt>. The
 * result is <tt>false</tt> if and only if at least one of the following
 * is true:
 * <ul><li><tt>toffset</tt> is negative.
 * <li><tt>ooffset</tt> is negative.
 * <li><tt>toffset+len</tt> is greater than the length of this
 * <tt>String</tt> object.
 * <li><tt>ooffset+len</tt> is greater than the length of the other
 * argument.
 * <li>There is some nonnegative integer k less than <tt>len</tt>
 * such that:
 * <tt>this.charAt(toffset+k) != other.charAt(ooffset+k)</tt>
 * </ul>
 *
 * @param toffset the starting offset of the subregion in this string.
 * @param other the string argument.
 * @param ooffset the starting offset of the subregion in the string
 * argument.
 * @param len the number of characters to compare.
 * @return <code>true</code> if the specified subregion of this string
 * exactly matches the specified subregion of the string argument;
 * <code>false</code> otherwise.
 */
 public boolean regionMatches(int toffset, String other, int ooffset,
 int len) {
 char ta[] = value;
 int to = toffset;
 char pa[] = other.value;
 int po = ooffset;
 // Note: toffset, ooffset, or len might be near -1>>>1.
 if ((ooffset < 0) || (toffset < 0)
 || (toffset > (long)value.length - len)
 || (ooffset > (long)other.value.length - len)) {
 return false;
 }
 while (len-- > 0) {
 if (ta[to++] != pa[po++]) {
 return false;
 }
 }
 return true;
 }
 
 /**
 * Tests if two string regions are equal.
 * 
 * A substring of this <tt>String</tt> object is compared to a substring
 * of the argument <tt>other</tt>. The result is <tt>true</tt> if these
 * substrings represent character sequences that are the same, ignoring
 * case if and only if <tt>ignoreCase</tt> is true. The substring of
 * this <tt>String</tt> object to be compared begins at index
 * <tt>toffset</tt> and has length <tt>len</tt>. The substring of
 * <tt>other</tt> to be compared begins at index <tt>ooffset</tt> and
 * has length <tt>len</tt>. The result is <tt>false</tt> if and only if
 * at least one of the following is true:
 * <ul><li><tt>toffset</tt> is negative.
 * <li><tt>ooffset</tt> is negative.
 * <li><tt>toffset+len</tt> is greater than the length of this
 * <tt>String</tt> object.
 * <li><tt>ooffset+len</tt> is greater than the length of the other
 * argument.
 * <li><tt>ignoreCase</tt> is <tt>false</tt> and there is some nonnegative
 * integer k less than <tt>len</tt> such that:
 * <blockquote><pre>
 * this.charAt(toffset+k) != other.charAt(ooffset+k)
 * </pre></blockquote>
 * <li><tt>ignoreCase</tt> is <tt>true</tt> and there is some nonnegative
 * integer k less than <tt>len</tt> such that:
 * <blockquote><pre>
 * Character.toLowerCase(this.charAt(toffset+k)) !=
 Character.toLowerCase(other.charAt(ooffset+k))
 * </pre></blockquote>
 * and:
 * <blockquote><pre>
 * Character.toUpperCase(this.charAt(toffset+k)) !=
 * Character.toUpperCase(other.charAt(ooffset+k))
 * </pre></blockquote>
 * </ul>
 *
 * @param ignoreCase if <code>true</code>, ignore case when comparing
 * characters.
 * @param toffset the starting offset of the subregion in this
 * string.
 * @param other the string argument.
 * @param ooffset the starting offset of the subregion in the string
 * argument.
 * @param len the number of characters to compare.
 * @return <code>true</code> if the specified subregion of this string
 * matches the specified subregion of the string argument;
 * <code>false</code> otherwise. Whether the matching is exact
 * or case insensitive depends on the <code>ignoreCase</code>
 * argument.
 */
 public boolean regionMatches(boolean ignoreCase, int toffset,
 String other, int ooffset, int len) {
 char ta[] = value;
 int to = toffset;
 char pa[] = other.value;
 int po = ooffset;
 // Note: toffset, ooffset, or len might be near -1>>>1.
 if ((ooffset < 0) || (toffset < 0)
 || (toffset > (long)value.length - len)
 || (ooffset > (long)other.value.length - len)) {
 return false;
 }
 while (len-- > 0) {
 char c1 = ta[to++];
 char c2 = pa[po++];
 if (c1 == c2) {
 continue;
 }
 if (ignoreCase) {
 // If characters don't match but case may be ignored,
 // try converting both characters to uppercase.
 // If the results match, then the comparison scan should
 // continue.
 char u1 = Character.toUpperCase(c1);
 char u2 = Character.toUpperCase(c2);
 if (u1 == u2) {
 continue;
 }
 // Unfortunately, conversion to uppercase does not work properly
 // for the Georgian alphabet, which has strange rules about case
 // conversion. So we need to make one last check before
 // exiting.
 if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) {
 continue;
 }
 }
 return false;
 }
 return true;
 }
 
 /**
 * Tests if the substring of this string beginning at the
 * specified index starts with the specified prefix.
 *
 * @param prefix the prefix.
 * @param toffset where to begin looking in this string.
 * @return <code>true</code> if the character sequence represented by the
 * argument is a prefix of the substring of this object starting
 * at index <code>toffset</code>; <code>false</code> otherwise.
 * The result is <code>false</code> if <code>toffset</code> is
 * negative or greater than the length of this
 * <code>String</code> object; otherwise the result is the same
 * as the result of the expression
 * <pre>
 * this.substring(toffset).startsWith(prefix)
 * </pre>
 */
 public boolean startsWith(String prefix, int toffset) {
 char ta[] = value;
 int to = toffset;
 char pa[] = prefix.value;
 int po = 0;
 int pc = prefix.value.length;
 // Note: toffset might be near -1>>>1.
 if ((toffset < 0) || (toffset > value.length - pc)) {
 return false;
 }
 while (--pc >= 0) {
 if (ta[to++] != pa[po++]) {
 return false;
 }
 }
 return true;
 }
 
 /**
 * Tests if this string starts with the specified prefix.
 *
 * @param prefix the prefix.
 * @return <code>true</code> if the character sequence represented by the
 * argument is a prefix of the character sequence represented by
 * this string; <code>false</code> otherwise.
 * Note also that <code>true</code> will be returned if the
 * argument is an empty string or is equal to this
 * <code>String</code> object as determined by the
 * {@link #equals(Object)} method.
 * @since 1. 0
 */
 public boolean startsWith(String prefix) {
 return startsWith(prefix, 0);
 }
 
 /**
 * Tests if this string ends with the specified suffix.
 *
 * @param suffix the suffix.
 * @return <code>true</code> if the character sequence represented by the
 * argument is a suffix of the character sequence represented by
 * this object; <code>false</code> otherwise. Note that the
 * result will be <code>true</code> if the argument is the
 * empty string or is equal to this <code>String</code> object
 * as determined by the {@link #equals(Object)} method.
 */
 public boolean endsWith(String suffix) {
 return startsWith(suffix, value.length - suffix.value.length);
 }
 
 /**
 * Returns a hash code for this string. The hash code for a
 * <code>String</code> object is computed as
 * <blockquote><pre>
 * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
 * </pre></blockquote>
 * using <code>int</code> arithmetic, where <code>s[i]</code> is the
 * ith character of the string, <code>n</code> is the length of
 * the string, and <code>^</code> indicates exponentiation.
 * (The hash value of the empty string is zero.)
 *
 * @return a hash code value for this object.
 */
 public int hashCode() {
 int h = hash;
 if (h == 0 && value.length > 0) {
 char val[] = value;
 
 for (int i = 0; i < value.length; i++) {
 h = 31 * h + val[i];
 }
 hash = h;
 }
 return h;
 }
 
 /**
 * Returns the index within this string of the first occurrence of
 * the specified character. If a character with value
 * <code>ch</code> occurs in the character sequence represented by
 * this <code>String</code> object, then the index (in Unicode
 * code units) of the first such occurrence is returned. For
 * values of <code>ch</code> in the range from 0 to 0xFFFF
 * (inclusive), this is the smallest value k such that:
 * <blockquote><pre>
 * this.charAt(k) == ch
 * </pre></blockquote>
 * is true. For other values of <code>ch</code>, it is the
 * smallest value k such that:
 * <blockquote><pre>
 * this.codePointAt(k) == ch
 * </pre></blockquote>
 * is true. In either case, if no such character occurs in this
 * string, then <code>-1</code> is returned.
 *
 * @param ch a character (Unicode code point).
 * @return the index of the first occurrence of the character in the
 * character sequence represented by this object, or
 * <code>-1</code> if the character does not occur.
 */
 public int indexOf(int ch) {
 return indexOf(ch, 0);
 }
 
 /**
 * Returns the index within this string of the first occurrence of the
 * specified character, starting the search at the specified index.
 * 
 * If a character with value <code>ch</code> occurs in the
 * character sequence represented by this <code>String</code>
 * object at an index no smaller than <code>fromIndex</code>, then
 * the index of the first such occurrence is returned. For values
 * of <code>ch</code> in the range from 0 to 0xFFFF (inclusive),
 * this is the smallest value k such that:
 * <blockquote><pre>
 * (this.charAt(k) == ch) && (k >= fromIndex)
 * </pre></blockquote>
 * is true. For other values of <code>ch</code>, it is the
 * smallest value k such that:
 * <blockquote><pre>
 * (this.codePointAt(k) == ch) && (k >= fromIndex)
 * </pre></blockquote>
 * is true. In either case, if no such character occurs in this
 * string at or after position <code>fromIndex</code>, then
 * <code>-1</code> is returned.
 *
 * 
 * There is no restriction on the value of <code>fromIndex</code>. If it
 * is negative, it has the same effect as if it were zero: this entire
 * string may be searched. If it is greater than the length of this
 * string, it has the same effect as if it were equal to the length of
 * this string: <code>-1</code> is returned.
 *
 * All indices are specified in <code>char</code> values
 * (Unicode code units).
 *
 * @param ch a character (Unicode code point).
 * @param fromIndex the index to start the search from.
 * @return the index of the first occurrence of the character in the
 * character sequence represented by this object that is greater
 * than or equal to <code>fromIndex</code>, or <code>-1</code>
 * if the character does not occur.
 */
 public int indexOf(int ch, int fromIndex) {
 final int max = value.length;
 if (fromIndex < 0) {
 fromIndex = 0;
 } else if (fromIndex >= max) {
 // Note: fromIndex might be near -1>>>1.
 return -1;
 }
 
 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
 // handle most cases here (ch is a BMP code point or a
 // negative value (invalid code point))
 final char[] value = this.value;
 for (int i = fromIndex; i < max; i++) {
 if (value[i] == ch) {
 return i;
 }
 }
 return -1;
 } else {
 return indexOfSupplementary(ch, fromIndex);
 }
 }
 
 /**
 * Handles (rare) calls of indexOf with a supplementary character.
 */
 private int indexOfSupplementary(int ch, int fromIndex) {
 if (Character.isValidCodePoint(ch)) {
 final char[] value = this.value;
 final char hi = Character.highSurrogate(ch);
 final char lo = Character.lowSurrogate(ch);
 final int max = value.length - 1;
 for (int i = fromIndex; i < max; i++) {
 if (value[i] == hi && value[i + 1] == lo) {
 return i;
 }
 }
 }
 return -1;
 }
 
 /**
 * Returns the index within this string of the last occurrence of
 * the specified character. For values of <code>ch</code> in the
 * range from 0 to 0xFFFF (inclusive), the index (in Unicode code
 * units) returned is the largest value k such that:
 * <blockquote><pre>
 * this.charAt(k) == ch
 * </pre></blockquote>
 * is true. For other values of <code>ch</code>, it is the
 * largest value k such that:
 * <blockquote><pre>
 * this.codePointAt(k) == ch
 * </pre></blockquote>
 * is true. In either case, if no such character occurs in this
 * string, then <code>-1</code> is returned. The
 * <code>String</code> is searched backwards starting at the last
 * character.
 *
 * @param ch a character (Unicode code point).
 * @return the index of the last occurrence of the character in the
 * character sequence represented by this object, or
 * <code>-1</code> if the character does not occur.
 */
 public int lastIndexOf(int ch) {
 return lastIndexOf(ch, value.length - 1);
 }
 
 /**
 * Returns the index within this string of the last occurrence of
 * the specified character, searching backward starting at the
 * specified index. For values of <code>ch</code> in the range
 * from 0 to 0xFFFF (inclusive), the index returned is the largest
 * value k such that:
 * <blockquote><pre>
 * (this.charAt(k) == ch) && (k <= fromIndex)
 * </pre></blockquote>
 * is true. For other values of <code>ch</code>, it is the
 * largest value k such that:
 * <blockquote><pre>
 * (this.codePointAt(k) == ch) && (k <= fromIndex)
 * </pre></blockquote>
 * is true. In either case, if no such character occurs in this
 * string at or before position <code>fromIndex</code>, then
 * <code>-1</code> is returned.
 *
 * All indices are specified in <code>char</code> values
 * (Unicode code units).
 *
 * @param ch a character (Unicode code point).
 * @param fromIndex the index to start the search from. There is no
 * restriction on the value of <code>fromIndex</code>. If it is
 * greater than or equal to the length of this string, it has
 * the same effect as if it were equal to one less than the
 * length of this string: this entire string may be searched.
 * If it is negative, it has the same effect as if it were -1:
 * -1 is returned.
 * @return the index of the last occurrence of the character in the
 * character sequence represented by this object that is less
 * than or equal to <code>fromIndex</code>, or <code>-1</code>
 * if the character does not occur before that point.
 */
 public int lastIndexOf(int ch, int fromIndex) {
 if (ch < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
 // handle most cases here (ch is a BMP code point or a
 // negative value (invalid code point))
 final char[] value = this.value;
 int i = Math.min(fromIndex, value.length - 1);
 for (; i >= 0; i--) {
 if (value[i] == ch) {
 return i;
 }
 }
 return -1;
 } else {
 return lastIndexOfSupplementary(ch, fromIndex);
 }
 }
 
 /**
 * Handles (rare) calls of lastIndexOf with a supplementary character.
 */
 private int lastIndexOfSupplementary(int ch, int fromIndex) {
 if (Character.isValidCodePoint(ch)) {
 final char[] value = this.value;
 char hi = Character.highSurrogate(ch);
 char lo = Character.lowSurrogate(ch);
 int i = Math.min(fromIndex, value.length - 2);
 for (; i >= 0; i--) {
 if (value[i] == hi && value[i + 1] == lo) {
 return i;
 }
 }
 }
 return -1;
 }
 
 /**
 * Returns the index within this string of the first occurrence of the
 * specified substring.
 *
 * The returned index is the smallest value k for which:
 * <blockquote><pre>
 * this.startsWith(str, k)
 * </pre></blockquote>
 * If no such value of k exists, then {@code -1} is returned.
 *
 * @param str the substring to search for.
 * @return the index of the first occurrence of the specified substring,
 * or {@code -1} if there is no such occurrence.
 */
 public int indexOf(String str) {
 return indexOf(str, 0);
 }
 
 /**
 * Returns the index within this string of the first occurrence of the
 * specified substring, starting at the specified index.
 *
 * The returned index is the smallest value k for which:
 * <blockquote><pre>
 * k >= fromIndex && this.startsWith(str, k)
 * </pre></blockquote>
 * If no such value of k exists, then {@code -1} is returned.
 *
 * @param str the substring to search for.
 * @param fromIndex the index from which to start the search.
 * @return the index of the first occurrence of the specified substring,
 * starting at the specified index,
 * or {@code -1} if there is no such occurrence.
 */
 public int indexOf(String str, int fromIndex) {
 return indexOf(value, 0, value.length,
 str.value, 0, str.value.length, fromIndex);
 }
 
 /**
 * Code shared by String and StringBuffer to do searches. The
 * source is the character array being searched, and the target
 * is the string being searched for.
 *
 * @param source the characters being searched.
 * @param sourceOffset offset of the source string.
 * @param sourceCount count of the source string.
 * @param target the characters being searched for.
 * @param targetOffset offset of the target string.
 * @param targetCount count of the target string.
 * @param fromIndex the index to begin searching from.
 */
 static int indexOf(char[] source, int sourceOffset, int sourceCount,
 char[] target, int targetOffset, int targetCount,
 int fromIndex) {
 if (fromIndex >= sourceCount) {
 return (targetCount == 0 ? sourceCount : -1);
 }
 if (fromIndex < 0) {
 fromIndex = 0;
 }
 if (targetCount == 0) {
 return fromIndex;
 }
 
 char first = target[targetOffset];
 int max = sourceOffset + (sourceCount - targetCount);
 
 for (int i = sourceOffset + fromIndex; i <= max; i++) {
 /* Look for first character. */
 if (source[i] != first) {
 while (++i <= max && source[i] != first);
 }
 
 /* Found first character, now look at the rest of v2 */
 if (i <= max) {
 int j = i + 1;
 int end = j + targetCount - 1;
 for (int k = targetOffset + 1; j < end && source[j]
 == target[k]; j++, k++);
 
 if (j == end) {
 /* Found whole string. */
 return i - sourceOffset;
 }
 }
 }
 return -1;
 }
 
 /**
 * Returns the index within this string of the last occurrence of the
 * specified substring. The last occurrence of the empty string ""
 * is considered to occur at the index value {@code this.length()}.
 *
 * The returned index is the largest value k for which:
 * <blockquote><pre>
 * this.startsWith(str, k)
 * </pre></blockquote>
 * If no such value of k exists, then {@code -1} is returned.
 *
 * @param str the substring to search for.
 * @return the index of the last occurrence of the specified substring,
 * or {@code -1} if there is no such occurrence.
 */
 public int lastIndexOf(String str) {
 return lastIndexOf(str, value.length);
 }
 
 /**
 * Returns the index within this string of the last occurrence of the
 * specified substring, searching backward starting at the specified index.
 *
 * The returned index is the largest value k for which:
 * <blockquote><pre>
 * k <= fromIndex && this.startsWith(str, k)
 * </pre></blockquote>
 * If no such value of k exists, then {@code -1} is returned.
 *
 * @param str the substring to search for.
 * @param fromIndex the index to start the search from.
 * @return the index of the last occurrence of the specified substring,
 * searching backward from the specified index,
 * or {@code -1} if there is no such occurrence.
 */
 public int lastIndexOf(String str, int fromIndex) {
 return lastIndexOf(value, 0, value.length,
 str.value, 0, str.value.length, fromIndex);
 }
 
 /**
 * Code shared by String and StringBuffer to do searches. The
 * source is the character array being searched, and the target
 * is the string being searched for.
 *
 * @param source the characters being searched.
 * @param sourceOffset offset of the source string.
 * @param sourceCount count of the source string.
 * @param target the characters being searched for.
 * @param targetOffset offset of the target string.
 * @param targetCount count of the target string.
 * @param fromIndex the index to begin searching from.
 */
 static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
 char[] target, int targetOffset, int targetCount,
 int fromIndex) {
 /*
 * Check arguments; return immediately where possible. For
 * consistency, don't check for null str.
 */
 int rightIndex = sourceCount - targetCount;
 if (fromIndex < 0) {
 return -1;
 }
 if (fromIndex > rightIndex) {
 fromIndex = rightIndex;
 }
 /* Empty string always matches. */
 if (targetCount == 0) {
 return fromIndex;
 }
 
 int strLastIndex = targetOffset + targetCount - 1;
 char strLastChar = target[strLastIndex];
 int min = sourceOffset + targetCount - 1;
 int i = min + fromIndex;
 
 startSearchForLastChar:
 while (true) {
 while (i >= min && source[i] != strLastChar) {
 i--;
 }
 if (i < min) {
 return -1;
 }
 int j = i - 1;
 int start = j - (targetCount - 1);
 int k = strLastIndex - 1;
 
 while (j > start) {
 if (source[j--] != target[k--]) {
 i--;
 continue startSearchForLastChar;
 }
 }
 return start - sourceOffset + 1;
 }
 }
 
 /**
 * Returns a new string that is a substring of this string. The
 * substring begins with the character at the specified index and
 * extends to the end of this string. 
 * Examples:
 * <blockquote><pre>
 * "unhappy".substring(2) returns "happy"
 * "Harbison".substring(3) returns "bison"
 * "emptiness".substring(9) returns "" (an empty string)
 * </pre></blockquote>
 *
 * @param beginIndex the beginning index, inclusive.
 * @return the specified substring.
 * @exception IndexOutOfBoundsException if
 * <code>beginIndex</code> is negative or larger than the
 * length of this <code>String</code> object.
 */
 public String substring(int beginIndex) {
 if (beginIndex < 0) {
 throw new StringIndexOutOfBoundsException(beginIndex);
 }
 int subLen = value.length - beginIndex;
 if (subLen < 0) {
 throw new StringIndexOutOfBoundsException(subLen);
 }
 return (beginIndex == 0) ? this : new String(value, beginIndex, subLen);
 }
 
 /**
 * Returns a new string that is a substring of this string. The
 * substring begins at the specified <code>beginIndex</code> and
 * extends to the character at index <code>endIndex - 1</code>.
 * Thus the length of the substring is <code>endIndex-beginIndex</code>.
 * 
 * Examples:
 * <blockquote><pre>
 * "hamburger".substring(4, 8) returns "urge"
 * "smiles".substring(1, 5) returns "mile"
 * </pre></blockquote>
 *
 * @param beginIndex the beginning index, inclusive.
 * @param endIndex the ending index, exclusive.
 * @return the specified substring.
 * @exception IndexOutOfBoundsException if the
 * <code>beginIndex</code> is negative, or
 * <code>endIndex</code> is larger than the length of
 * this <code>String</code> object, or
 * <code>beginIndex</code> is larger than
 * <code>endIndex</code>.
 */
 public String substring(int beginIndex, int endIndex) {
 if (beginIndex < 0) {
 throw new StringIndexOutOfBoundsException(beginIndex);
 }
 if (endIndex > value.length) {
 throw new StringIndexOutOfBoundsException(endIndex);
 }
 int subLen = endIndex - beginIndex;
 if (subLen < 0) {
 throw new StringIndexOutOfBoundsException(subLen);
 }
 return ((beginIndex == 0) && (endIndex == value.length)) ? this
 : new String(value, beginIndex, subLen);
 }
 
 /**
 * Returns a new character sequence that is a subsequence of this sequence.
 *
 * An invocation of this method of the form
 *
 * <blockquote><pre>
 * str.subSequence(begin, end)</pre></blockquote>
 *
 * behaves in exactly the same way as the invocation
 *
 * <blockquote><pre>
 * str.substring(begin, end)</pre></blockquote>
 *
 * This method is defined so that the <tt>String</tt> class can implement
 * the {@link CharSequence} interface. 
 *
 * @param beginIndex the begin index, inclusive.
 * @param endIndex the end index, exclusive.
 * @return the specified subsequence.
 *
 * @throws IndexOutOfBoundsException
 * if <tt>beginIndex</tt> or <tt>endIndex</tt> are negative,
 * if <tt>endIndex</tt> is greater than <tt>length()</tt>,
 * or if <tt>beginIndex</tt> is greater than <tt>startIndex</tt>
 *
 * @since 1.4
 * @spec JSR-51
 */
 public CharSequence subSequence(int beginIndex, int endIndex) {
 return this.substring(beginIndex, endIndex);
 }
 
 /**
 * Concatenates the specified string to the end of this string.
 * 
 * If the length of the argument string is <code>0</code>, then this
 * <code>String</code> object is returned. Otherwise, a new
 * <code>String</code> object is created, representing a character
 * sequence that is the concatenation of the character sequence
 * represented by this <code>String</code> object and the character
 * sequence represented by the argument string.
 * Examples:
 * <blockquote><pre>
 * "cares".concat("s") returns "caress"
 * "to".concat("get").concat("her") returns "together"
 * </pre></blockquote>
 *
 * @param str the <code>String</code> that is concatenated to the end
 * of this <code>String</code>.
 * @return a string that represents the concatenation of this object's
 * characters followed by the string argument's characters.
 */
 public String concat(String str) {
 int otherLen = str.length();
 if (otherLen == 0) {
 return this;
 }
 int len = value.length;
 char buf[] = Arrays.copyOf(value, len + otherLen);
 str.getChars(buf, len);
 return new String(buf, true);
 }
 
 /**
 * Returns a new string resulting from replacing all occurrences of
 * <code>oldChar</code> in this string with <code>newChar</code>.
 * 
 * If the character <code>oldChar</code> does not occur in the
 * character sequence represented by this <code>String</code> object,
 * then a reference to this <code>String</code> object is returned.
 * Otherwise, a new <code>String</code> object is created that
 * represents a character sequence identical to the character sequence
 * represented by this <code>String</code> object, except that every
 * occurrence of <code>oldChar</code> is replaced by an occurrence
 * of <code>newChar</code>.
 * 
 * Examples:
 * <blockquote><pre>
 * "mesquite in your cellar".replace('e', 'o')
 * returns "mosquito in your collar"
 * "the war of baronets".replace('r', 'y')
 * returns "the way of bayonets"
 * "sparring with a purple porpoise".replace('p', 't')
 * returns "starring with a turtle tortoise"
 * "JonL".replace('q', 'x') returns "JonL" (no change)
 * </pre></blockquote>
 *
 * @param oldChar the old character.
 * @param newChar the new character.
 * @return a string derived from this string by replacing every
 * occurrence of <code>oldChar</code> with <code>newChar</code>.
 */
 public String replace(char oldChar, char newChar) {
 if (oldChar != newChar) {
 int len = value.length;
 int i = -1;
 char[] val = value; /* avoid getfield opcode */
 
 while (++i < len) {
 if (val[i] == oldChar) {
 break;
 }
 }
 if (i < len) {
 char buf[] = new char[len];
 for (int j = 0; j < i; j++) {
 buf[j] = val[j];
 }
 while (i < len) {
 char c = val[i];
 buf[i] = (c == oldChar) ? newChar : c;
 i++;
 }
 return new String(buf, true);
 }
 }
 return this;
 }
 
 /**
 * Tells whether or not this string matches the given <a
 * href="../util/regex/Pattern.html#sum">regular expression</a>.
 *
 * An invocation of this method of the form
 * str<tt>.matches(</tt>regex<tt>)</tt> yields exactly the
 * same result as the expression
 *
 * <blockquote><tt> {@link java.util.regex.Pattern}.{@link
 * java.util.regex.Pattern#matches(String,CharSequence)
 * matches}(</tt>regex<tt>,</tt> str<tt>)</tt></blockquote>
 *
 * @param regex
 * the regular expression to which this string is to be matched
 *
 * @return <tt>true</tt> if, and only if, this string matches the
 * given regular expression
 *
 * @throws PatternSyntaxException
 * if the regular expression's syntax is invalid
 *
 * @see java.util.regex.Pattern
 *
 * @since 1.4
 * @spec JSR-51
 */
 public boolean matches(String regex) {
 return Pattern.matches(regex, this);
 }
 
 /**
 * Returns true if and only if this string contains the specified
 * sequence of char values.
 *
 * @param s the sequence to search for
 * @return true if this string contains <code>s</code>, false otherwise
 * @throws NullPointerException if <code>s</code> is <code>null</code>
 * @since 1.5
 */
 public boolean contains(CharSequence s) {
 return indexOf(s.toString()) > -1;
 }
 
 /**
 * Replaces the first substring of this string that matches the given <a
 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
 * given replacement.
 *
 * An invocation of this method of the form
 * str<tt>.replaceFirst(</tt>regex<tt>,</tt> repl<tt>)</tt>
 * yields exactly the same result as the expression
 *
 * <blockquote><tt>
 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile
 * compile}(</tt>regex<tt>).{@link
 * java.util.regex.Pattern#matcher(java.lang.CharSequence)
 * matcher}(</tt>str<tt>).{@link java.util.regex.Matcher#replaceFirst
 * replaceFirst}(</tt>repl<tt>)</tt></blockquote>
 *
 *
 * Note that backslashes (<tt>\</tt>) and dollar signs (<tt>$</tt>) in the
 * replacement string may cause the results to be different than if it were
 * being treated as a literal replacement string; see
 * {@link java.util.regex.Matcher#replaceFirst}.
 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
 * meaning of these characters, if desired.
 *
 * @param regex
 * the regular expression to which this string is to be matched
 * @param replacement
 * the string to be substituted for the first match
 *
 * @return The resulting <tt>String</tt>
 *
 * @throws PatternSyntaxException
 * if the regular expression's syntax is invalid
 *
 * @see java.util.regex.Pattern
 *
 * @since 1.4
 * @spec JSR-51
 */
 public String replaceFirst(String regex, String replacement) {
 return Pattern.compile(regex).matcher(this).replaceFirst(replacement);
 }
 
 /**
 * Replaces each substring of this string that matches the given <a
 * href="../util/regex/Pattern.html#sum">regular expression</a> with the
 * given replacement.
 *
 * An invocation of this method of the form
 * str<tt>.replaceAll(</tt>regex<tt>,</tt> repl<tt>)</tt>
 * yields exactly the same result as the expression
 *
 * <blockquote><tt>
 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile
 * compile}(</tt>regex<tt>).{@link
 * java.util.regex.Pattern#matcher(java.lang.CharSequence)
 * matcher}(</tt>str<tt>).{@link java.util.regex.Matcher#replaceAll
 * replaceAll}(</tt>repl<tt>)</tt></blockquote>
 *
 *
 * Note that backslashes (<tt>\</tt>) and dollar signs (<tt>$</tt>) in the
 * replacement string may cause the results to be different than if it were
 * being treated as a literal replacement string; see
 * {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}.
 * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
 * meaning of these characters, if desired.
 *
 * @param regex
 * the regular expression to which this string is to be matched
 * @param replacement
 * the string to be substituted for each match
 *
 * @return The resulting <tt>String</tt>
 *
 * @throws PatternSyntaxException
 * if the regular expression's syntax is invalid
 *
 * @see java.util.regex.Pattern
 *
 * @since 1.4
 * @spec JSR-51
 */
 public String replaceAll(String regex, String replacement) {
 return Pattern.compile(regex).matcher(this).replaceAll(replacement);
 }
 
 /**
 * Replaces each substring of this string that matches the literal target
 * sequence with the specified literal replacement sequence. The
 * replacement proceeds from the beginning of the string to the end, for
 * example, replacing "aa" with "b" in the string "aaa" will result in
 * "ba" rather than "ab".
 *
 * @param target The sequence of char values to be replaced
 * @param replacement The replacement sequence of char values
 * @return The resulting string
 * @throws NullPointerException if <code>target</code> or
 * <code>replacement</code> is <code>null</code>.
 * @since 1.5
 */
 public String replace(CharSequence target, CharSequence replacement) {
 return Pattern.compile(target.toString(), Pattern.LITERAL).matcher(
 this).replaceAll(Matcher.quoteReplacement(replacement.toString()));
 }
 
 /**
 * Splits this string around matches of the given
 * <a href="../util/regex/Pattern.html#sum">regular expression</a>.
 *
 * The array returned by this method contains each substring of this
 * string that is terminated by another substring that matches the given
 * expression or is terminated by the end of the string. The substrings in
 * the array are in the order in which they occur in this string. If the
 * expression does not match any part of the input then the resulting array
 * has just one element, namely this string.
 *
 * The <tt>limit</tt> parameter controls the number of times the
 * pattern is applied and therefore affects the length of the resulting
 * array. If the limit n is greater than zero then the pattern
 * will be applied at most n - 1 times, the array's
 * length will be no greater than n, and the array's last entry
 * will contain all input beyond the last matched delimiter. If n
 * is non-positive then the pattern will be applied as many times as
 * possible and the array can have any length. If n is zero then
 * the pattern will be applied as many times as possible, the array can
 * have any length, and trailing empty strings will be discarded.
 *
 * The string <tt>"boo:and:foo"</tt>, for example, yields the
 * following results with these parameters:
 *
 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split example showing regex, limit, and result">
 * <tr>
 * <th>Regex</th>
 * <th>Limit</th>
 * <th>Result</th>
 * </tr>
 * <tr><td align=center>:</td>
 * <td align=center>2</td>
 * <td><tt>{ "boo", "and:foo" }</tt></td></tr>
 * <tr><td align=center>:</td>
 * <td align=center>5</td>
 * <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
 * <tr><td align=center>:</td>
 * <td align=center>-2</td>
 * <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
 * <tr><td align=center>o</td>
 * <td align=center>5</td>
 * <td><tt>{ "b", "", ":and:f", "", "" }</tt></td></tr>
 * <tr><td align=center>o</td>
 * <td align=center>-2</td>
 * <td><tt>{ "b", "", ":and:f", "", "" }</tt></td></tr>
 * <tr><td align=center>o</td>
 * <td align=center>0</td>
 * <td><tt>{ "b", "", ":and:f" }</tt></td></tr>
 * </table></blockquote>
 *
 * An invocation of this method of the form
 * str.<tt>split(</tt>regex<tt>,</tt> n<tt>)</tt>
 * yields the same result as the expression
 *
 * <blockquote>
 * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile
 * compile}<tt>(</tt>regex<tt>)</tt>.{@link
 * java.util.regex.Pattern#split(java.lang.CharSequence,int)
 * split}<tt>(</tt>str<tt>,</tt> n<tt>)</tt>
 * </blockquote>
 *
 *
 * @param regex
 * the delimiting regular expression
 *
 * @param limit
 * the result threshold, as described above
 *
 * @return the array of strings computed by splitting this string
 * around matches of the given regular expression
 *
 * @throws PatternSyntaxException
 * if the regular expression's syntax is invalid
 *
 * @see java.util.regex.Pattern
 *
 * @since 1.4
 * @spec JSR-51
 */
 public String[] split(String regex, int limit) {
 /* fastpath if the regex is a
 (1)one-char String and this character is not one of the
 RegEx's meta characters ".$|()[{^?*+\\", or
 (2)two-char String and the first char is the backslash and
 the second is not the ascii digit or ascii letter.
 */
 char ch = 0;
 if (((regex.value.length == 1 &&
 ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||
 (regex.length() == 2 &&
 regex.charAt(0) == '\\' &&
 (((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&
 ((ch-'a')|('z'-ch)) < 0 &&
 ((ch-'A')|('Z'-ch)) < 0)) &&
 (ch < Character.MIN_HIGH_SURROGATE ||
 ch > Character.MAX_LOW_SURROGATE))
 {
 int off = 0;
 int next = 0;
 boolean limited = limit > 0;
 ArrayList<String> list = new ArrayList<>();
 while ((next = indexOf(ch, off)) != -1) {
 if (!limited || list.size() < limit - 1) {
 list.add(substring(off, next));
 off = next + 1;
 } else { // last one
 //assert (list.size() == limit - 1);
 list.add(substring(off, value.length));
 off = value.length;
 break;
 }
 }
 // If no match was found, return this
 if (off == 0)
 return new String[]{this};
 
 // Add remaining segment
 if (!limited || list.size() < limit)
 list.add(substring(off, value.length));
 
 // Construct result
 int resultSize = list.size();
 if (limit == 0)
 while (resultSize > 0 && list.get(resultSize - 1).length() == 0)
 resultSize--;
 String[] result = new String[resultSize];
 return list.subList(0, resultSize).toArray(result);
 }
 return Pattern.compile(regex).split(this, limit);
 }
 
 /**
 * Splits this string around matches of the given <a
 * href="../util/regex/Pattern.html#sum">regular expression</a>.
 *
 * This method works as if by invoking the two-argument {@link
 * #split(String, int) split} method with the given expression and a limit
 * argument of zero. Trailing empty strings are therefore not included in
 * the resulting array.
 *
 * The string <tt>"boo:and:foo"</tt>, for example, yields the following
 * results with these expressions:
 *
 * <blockquote><table cellpadding=1 cellspacing=0 summary="Split examples showing regex and result">
 * <tr>
 * <th>Regex</th>
 * <th>Result</th>
 * </tr>
 * <tr><td align=center>:</td>
 * <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
 * <tr><td align=center>o</td>
 * <td><tt>{ "b", "", ":and:f" }</tt></td></tr>
 * </table></blockquote>
 *
 *
 * @param regex
 * the delimiting regular expression
 *
 * @return the array of strings computed by splitting this string
 * around matches of the given regular expression
 *
 * @throws PatternSyntaxException
 * if the regular expression's syntax is invalid
 *
 * @see java.util.regex.Pattern
 *
 * @since 1.4
 * @spec JSR-51
 */
 public String[] split(String regex) {
 return split(regex, 0);
 }
 
 /**
 * Converts all of the characters in this <code>String</code> to lower
 * case using the rules of the given <code>Locale</code>. Case mapping is based
 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
 * class. Since case mappings are not always 1:1 char mappings, the resulting
 * <code>String</code> may be a different length than the original <code>String</code>.
 * 
 * Examples of lowercase mappings are in the following table:
 * <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description">
 * <tr>
 * <th>Language Code of Locale</th>
 * <th>Upper Case</th>
 * <th>Lower Case</th>
 * <th>Description</th>
 * </tr>
 * <tr>
 * <td>tr (Turkish)</td>
 * <td>\u0130</td>
 * <td>\u0069</td>
 * <td>capital letter I with dot above -> small letter i</td>
 * </tr>
 * <tr>
 * <td>tr (Turkish)</td>
 * <td>\u0049</td>
 * <td>\u0131</td>
 * <td>capital letter I -> small letter dotless i </td>
 * </tr>
 * <tr>
 * <td>(all)</td>
 * <td>French Fries</td>
 * <td>french fries</td>
 * <td>lowercased all chars in String</td>
 * </tr>
 * <tr>
 * <td>(all)</td>
 * <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi">
 * <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil">
 * <img src="doc-files/capsigma.gif" alt="capsigma"></td>
 * <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi">
 * <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon">
 * <img src="doc-files/sigma1.gif" alt="sigma"></td>
 * <td>lowercased all chars in String</td>
 * </tr>
 * </table>
 *
 * @param locale use the case transformation rules for this locale
 * @return the <code>String</code>, converted to lowercase.
 * @see java.lang.String#toLowerCase()
 * @see java.lang.String#toUpperCase()
 * @see java.lang.String#toUpperCase(Locale)
 * @since 1.1
 */
 public String toLowerCase(Locale locale) {
 if (locale == null) {
 throw new NullPointerException();
 }
 
 int firstUpper;
 final int len = value.length;
 
 /* Now check if there are any characters that need to be changed. */
 scan: {
 for (firstUpper = 0 ; firstUpper < len; ) {
 char c = value[firstUpper];
 if ((c >= Character.MIN_HIGH_SURROGATE)
 && (c <= Character.MAX_HIGH_SURROGATE)) {
 int supplChar = codePointAt(firstUpper);
 if (supplChar != Character.toLowerCase(supplChar)) {
 break scan;
 }
 firstUpper += Character.charCount(supplChar);
 } else {
 if (c != Character.toLowerCase(c)) {
 break scan;
 }
 firstUpper++;
 }
 }
 return this;
 }
 
 char[] result = new char[len];
 int resultOffset = 0; /* result may grow, so i+resultOffset
 * is the write location in result */
 
 /* Just copy the first few lowerCase characters. */
 System.arraycopy(value, 0, result, 0, firstUpper);
 
 String lang = locale.getLanguage();
 boolean localeDependent =
 (lang == "tr" || lang == "az" || lang == "lt");
 char[] lowerCharArray;
 int lowerChar;
 int srcChar;
 int srcCount;
 for (int i = firstUpper; i < len; i += srcCount) {
 srcChar = (int)value[i];
 if ((char)srcChar >= Character.MIN_HIGH_SURROGATE
 && (char)srcChar <= Character.MAX_HIGH_SURROGATE) {
 srcChar = codePointAt(i);
 srcCount = Character.charCount(srcChar);
 } else {
 srcCount = 1;
 }
 if (localeDependent || srcChar == '\u03A3') { // GREEK CAPITAL LETTER SIGMA
 lowerChar = ConditionalSpecialCasing.toLowerCaseEx(this, i, locale);
 } else if (srcChar == '\u0130') { // LATIN CAPITAL LETTER I DOT
 lowerChar = Character.ERROR;
 } else {
 lowerChar = Character.toLowerCase(srcChar);
 }
 if ((lowerChar == Character.ERROR)
 || (lowerChar >= Character.MIN_SUPPLEMENTARY_CODE_POINT)) {
 if (lowerChar == Character.ERROR) {
 if (!localeDependent && srcChar == '\u0130') {
 lowerCharArray =
 ConditionalSpecialCasing.toLowerCaseCharArray(this, i, Locale.ENGLISH);
 } else {
 lowerCharArray =
 ConditionalSpecialCasing.toLowerCaseCharArray(this, i, locale);
 }
 } else if (srcCount == 2) {
 resultOffset += Character.toChars(lowerChar, result, i + resultOffset) - srcCount;
 continue;
 } else {
 lowerCharArray = Character.toChars(lowerChar);
 }
 
 /* Grow result if needed */
 int mapLen = lowerCharArray.length;
 if (mapLen > srcCount) {
 char[] result2 = new char[result.length + mapLen - srcCount];
 System.arraycopy(result, 0, result2, 0, i + resultOffset);
 result = result2;
 }
 for (int x = 0; x < mapLen; ++x) {
 result[i + resultOffset + x] = lowerCharArray[x];
 }
 resultOffset += (mapLen - srcCount);
 } else {
 result[i + resultOffset] = (char)lowerChar;
 }
 }
 return new String(result, 0, len + resultOffset);
 }
 
 /**
 * Converts all of the characters in this <code>String</code> to lower
 * case using the rules of the default locale. This is equivalent to calling
 * <code>toLowerCase(Locale.getDefault())</code>.
 * 
 * Note: This method is locale sensitive, and may produce unexpected
 * results if used for strings that are intended to be interpreted locale
 * independently.
 * Examples are programming language identifiers, protocol keys, and HTML
 * tags.
 * For instance, <code>"TITLE".toLowerCase()</code> in a Turkish locale
 * returns <code>"t\u005Cu0131tle"</code>, where '\u005Cu0131' is the
 * LATIN SMALL LETTER DOTLESS I character.
 * To obtain correct results for locale insensitive strings, use
 * <code>toLowerCase(Locale.ENGLISH)</code>.
 * 
 * @return the <code>String</code>, converted to lowercase.
 * @see java.lang.String#toLowerCase(Locale)
 */
 public String toLowerCase() {
 return toLowerCase(Locale.getDefault());
 }
 
 /**
 * Converts all of the characters in this <code>String</code> to upper
 * case using the rules of the given <code>Locale</code>. Case mapping is based
 * on the Unicode Standard version specified by the {@link java.lang.Character Character}
 * class. Since case mappings are not always 1:1 char mappings, the resulting
 * <code>String</code> may be a different length than the original <code>String</code>.
 * 
 * Examples of locale-sensitive and 1:M case mappings are in the following table.
 * 
 * <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.">
 * <tr>
 * <th>Language Code of Locale</th>
 * <th>Lower Case</th>
 * <th>Upper Case</th>
 * <th>Description</th>
 * </tr>
 * <tr>
 * <td>tr (Turkish)</td>
 * <td>\u0069</td>
 * <td>\u0130</td>
 * <td>small letter i -> capital letter I with dot above</td>
 * </tr>
 * <tr>
 * <td>tr (Turkish)</td>
 * <td>\u0131</td>
 * <td>\u0049</td>
 * <td>small letter dotless i -> capital letter I</td>
 * </tr>
 * <tr>
 * <td>(all)</td>
 * <td>\u00df</td>
 * <td>\u0053 \u0053</td>
 * <td>small letter sharp s -> two letters: SS</td>
 * </tr>
 * <tr>
 * <td>(all)</td>
 * <td>Fahrvergnügen</td>
 * <td>FAHRVERGNÜGEN</td>
 * <td></td>
 * </tr>
 * </table>
 * @param locale use the case transformation rules for this locale
 * @return the <code>String</code>, converted to uppercase.
 * @see java.lang.String#toUpperCase()
 * @see java.lang.String#toLowerCase()
 * @see java.lang.String#toLowerCase(Locale)
 * @since 1.1
 */
 public String toUpperCase(Locale locale) {
 if (locale == null) {
 throw new NullPointerException();
 }
 
 int firstLower;
 final int len = value.length;
 
 /* Now check if there are any characters that need to be changed. */
 scan: {
 for (firstLower = 0 ; firstLower < len; ) {
 int c = (int)value[firstLower];
 int srcCount;
 if ((c >= Character.MIN_HIGH_SURROGATE)
 && (c <= Character.MAX_HIGH_SURROGATE)) {
 c = codePointAt(firstLower);
 srcCount = Character.charCount(c);
 } else {
 srcCount = 1;
 }
 int upperCaseChar = Character.toUpperCaseEx(c);
 if ((upperCaseChar == Character.ERROR)
 || (c != upperCaseChar)) {
 break scan;
 }
 firstLower += srcCount;
 }
 return this;
 }
 
 char[] result = new char[len]; /* may grow */
 int resultOffset = 0; /* result may grow, so i+resultOffset
 * is the write location in result */
 
 /* Just copy the first few upperCase characters. */
 System.arraycopy(value, 0, result, 0, firstLower);
 
 String lang = locale.getLanguage();
 boolean localeDependent =
 (lang == "tr" || lang == "az" || lang == "lt");
 char[] upperCharArray;
 int upperChar;
 int srcChar;
 int srcCount;
 for (int i = firstLower; i < len; i += srcCount) {
 srcChar = (int)value[i];
 if ((char)srcChar >= Character.MIN_HIGH_SURROGATE &&
 (char)srcChar <= Character.MAX_HIGH_SURROGATE) {
 srcChar = codePointAt(i);
 srcCount = Character.charCount(srcChar);
 } else {
 srcCount = 1;
 }
 if (localeDependent) {
 upperChar = ConditionalSpecialCasing.toUpperCaseEx(this, i, locale);
 } else {
 upperChar = Character.toUpperCaseEx(srcChar);
 }
 if ((upperChar == Character.ERROR)
 || (upperChar >= Character.MIN_SUPPLEMENTARY_CODE_POINT)) {
 if (upperChar == Character.ERROR) {
 if (localeDependent) {
 upperCharArray =
 ConditionalSpecialCasing.toUpperCaseCharArray(this, i, locale);
 } else {
 upperCharArray = Character.toUpperCaseCharArray(srcChar);
 }
 } else if (srcCount == 2) {
 resultOffset += Character.toChars(upperChar, result, i + resultOffset) - srcCount;
 continue;
 } else {
 upperCharArray = Character.toChars(upperChar);
 }
 
 /* Grow result if needed */
 int mapLen = upperCharArray.length;
 if (mapLen > srcCount) {
 char[] result2 = new char[result.length + mapLen - srcCount];
 System.arraycopy(result, 0, result2, 0, i + resultOffset);
 result = result2;
 }
 for (int x = 0; x < mapLen; ++x) {
 result[i + resultOffset + x] = upperCharArray[x];
 }
 resultOffset += (mapLen - srcCount);
 } else {
 result[i + resultOffset] = (char)upperChar;
 }
 }
 return new String(result, 0, len + resultOffset);
 }
 
 /**
 * Converts all of the characters in this <code>String</code> to upper
 * case using the rules of the default locale. This method is equivalent to
 * <code>toUpperCase(Locale.getDefault())</code>.
 * 
 * Note: This method is locale sensitive, and may produce unexpected
 * results if used for strings that are intended to be interpreted locale
 * independently.
 * Examples are programming language identifiers, protocol keys, and HTML
 * tags.
 * For instance, <code>"title".toUpperCase()</code> in a Turkish locale
 * returns <code>"T\u005Cu0130TLE"</code>, where '\u005Cu0130' is the
 * LATIN CAPITAL LETTER I WITH DOT ABOVE character.
 * To obtain correct results for locale insensitive strings, use
 * <code>toUpperCase(Locale.ENGLISH)</code>.
 * 
 * @return the <code>String</code>, converted to uppercase.
 * @see java.lang.String#toUpperCase(Locale)
 */
 public String toUpperCase() {
 return toUpperCase(Locale.getDefault());
 }
 
 /**
 * Returns a copy of the string, with leading and trailing whitespace
 * omitted.
 * 
 * If this <code>String</code> object represents an empty character
 * sequence, or the first and last characters of character sequence
 * represented by this <code>String</code> object both have codes
 * greater than <code>'\u0020'</code> (the space character), then a
 * reference to this <code>String</code> object is returned.
 * 
 * Otherwise, if there is no character with a code greater than
 * <code>'\u0020'</code> in the string, then a new
 * <code>String</code> object representing an empty string is created
 * and returned.
 * 
 * Otherwise, let k be the index of the first character in the
 * string whose code is greater than <code>'\u0020'</code>, and let
 * m be the index of the last character in the string whose code
 * is greater than <code>'\u0020'</code>. A new <code>String</code>
 * object is created, representing the substring of this string that
 * begins with the character at index k and ends with the
 * character at index m-that is, the result of
 * <code>this.substring(k, m+1)</code>.
 * 
 * This method may be used to trim whitespace (as defined above) from
 * the beginning and end of a string.
 *
 * @return A copy of this string with leading and trailing white
 * space removed, or this string if it has no leading or
 * trailing white space.
 */
 public String trim() {
 int len = value.length;
 int st = 0;
 char[] val = value; /* avoid getfield opcode */
 
 while ((st < len) && (val[st] <= ' ')) {
 st++;
 }
 while ((st < len) && (val[len - 1] <= ' ')) {
 len--;
 }
 return ((st > 0) || (len < value.length)) ? substring(st, len) : this;
 }
 
 /**
 * This object (which is already a string!) is itself returned.
 *
 * @return the string itself.
 */
 public String toString() {
 return this;
 }
 
 /**
 * Converts this string to a new character array.
 *
 * @return a newly allocated character array whose length is the length
 * of this string and whose contents are initialized to contain
 * the character sequence represented by this string.
 */
 public char[] toCharArray() {
 // Cannot use Arrays.copyOf because of class initialization order issues
 char result[] = new char[value.length];
 System.arraycopy(value, 0, result, 0, value.length);
 return result;
 }
 
 /**
 * Returns a formatted string using the specified format string and
 * arguments.
 *
 * The locale always used is the one returned by {@link
 * java.util.Locale#getDefault() Locale.getDefault()}.
 *
 * @param format
 * A <a href="../util/Formatter.html#syntax">format string</a>
 *
 * @param args
 * Arguments referenced by the format specifiers in the format
 * string. If there are more arguments than format specifiers, the
 * extra arguments are ignored. The number of arguments is
 * variable and may be zero. The maximum number of arguments is
 * limited by the maximum dimension of a Java array as defined by
 * <cite>The Java™ Virtual Machine Specification</cite>.
 * The behaviour on a
 * <tt>null</tt> argument depends on the <a
 * href="../util/Formatter.html#syntax">conversion</a>.
 *
 * @throws IllegalFormatException
 * If a format string contains an illegal syntax, a format
 * specifier that is incompatible with the given arguments,
 * insufficient arguments given the format string, or other
 * illegal conditions. For specification of all possible
 * formatting errors, see the <a
 * href="../util/Formatter.html#detail">Details</a> section of the
 * formatter class specification.
 *
 * @throws NullPointerException
 * If the <tt>format</tt> is <tt>null</tt>
 *
 * @return A formatted string
 *
 * @see java.util.Formatter
 * @since 1.5
 */
 public static String format(String format, Object... args) {
 return new Formatter().format(format, args).toString();
 }
 
 /**
 * Returns a formatted string using the specified locale, format string,
 * and arguments.
 *
 * @param l
 * The {@linkplain java.util.Locale locale} to apply during
 * formatting. If <tt>l</tt> is <tt>null</tt> then no localization
 * is applied.
 *
 * @param format
 * A <a href="../util/Formatter.html#syntax">format string</a>
 *
 * @param args
 * Arguments referenced by the format specifiers in the format
 * string. If there are more arguments than format specifiers, the
 * extra arguments are ignored. The number of arguments is
 * variable and may be zero. The maximum number of arguments is
 * limited by the maximum dimension of a Java array as defined by
 * <cite>The Java™ Virtual Machine Specification</cite>.
 * The behaviour on a
 * <tt>null</tt> argument depends on the <a
 * href="../util/Formatter.html#syntax">conversion</a>.
 *
 * @throws IllegalFormatException
 * If a format string contains an illegal syntax, a format
 * specifier that is incompatible with the given arguments,
 * insufficient arguments given the format string, or other
 * illegal conditions. For specification of all possible
 * formatting errors, see the <a
 * href="../util/Formatter.html#detail">Details</a> section of the
 * formatter class specification
 *
 * @throws NullPointerException
 * If the <tt>format</tt> is <tt>null</tt>
 *
 * @return A formatted string
 *
 * @see java.util.Formatter
 * @since 1.5
 */
 public static String format(Locale l, String format, Object... args) {
 return new Formatter(l).format(format, args).toString();
 }
 
 /**
 * Returns the string representation of the <code>Object</code> argument.
 *
 * @param obj an <code>Object</code>.
 * @return if the argument is <code>null</code>, then a string equal to
 * <code>"null"</code>; otherwise, the value of
 * <code>obj.toString()</code> is returned.
 * @see java.lang.Object#toString()
 */
 public static String valueOf(Object obj) {
 return (obj == null) ? "null" : obj.toString();
 }
 
 /**
 * Returns the string representation of the <code>char</code> array
 * argument. The contents of the character array are copied; subsequent
 * modification of the character array does not affect the newly
 * created string.
 *
 * @param data a <code>char</code> array.
 * @return a newly allocated string representing the same sequence of
 * characters contained in the character array argument.
 */
 public static String valueOf(char data[]) {
 return new String(data);
 }
 
 /**
 * Returns the string representation of a specific subarray of the
 * <code>char</code> array argument.
 * 
 * The <code>offset</code> argument is the index of the first
 * character of the subarray. The <code>count</code> argument
 * specifies the length of the subarray. The contents of the subarray
 * are copied; subsequent modification of the character array does not
 * affect the newly created string.
 *
 * @param data the character array.
 * @param offset the initial offset into the value of the
 * <code>String</code>.
 * @param count the length of the value of the <code>String</code>.
 * @return a string representing the sequence of characters contained
 * in the subarray of the character array argument.
 * @exception IndexOutOfBoundsException if <code>offset</code> is
 * negative, or <code>count</code> is negative, or
 * <code>offset+count</code> is larger than
 * <code>data.length</code>.
 */
 public static String valueOf(char data[], int offset, int count) {
 return new String(data, offset, count);
 }
 
 /**
 * Returns a String that represents the character sequence in the
 * array specified.
 *
 * @param data the character array.
 * @param offset initial offset of the subarray.
 * @param count length of the subarray.
 * @return a <code>String</code> that contains the characters of the
 * specified subarray of the character array.
 */
 public static String copyValueOf(char data[], int offset, int count) {
 // All public String constructors now copy the data.
 return new String(data, offset, count);
 }
 
 /**
 * Returns a String that represents the character sequence in the
 * array specified.
 *
 * @param data the character array.
 * @return a <code>String</code> that contains the characters of the
 * character array.
 */
 public static String copyValueOf(char data[]) {
 return new String(data);
 }
 
 /**
 * Returns the string representation of the <code>boolean</code> argument.
 *
 * @param b a <code>boolean</code>.
 * @return if the argument is <code>true</code>, a string equal to
 * <code>"true"</code> is returned; otherwise, a string equal to
 * <code>"false"</code> is returned.
 */
 public static String valueOf(boolean b) {
 return b ? "true" : "false";
 }
 
 /**
 * Returns the string representation of the <code>char</code>
 * argument.
 *
 * @param c a <code>char</code>.
 * @return a string of length <code>1</code> containing
 * as its single character the argument <code>c</code>.
 */
 public static String valueOf(char c) {
 char data[] = {c};
 return new String(data, true);
 }
 
 /**
 * Returns the string representation of the <code>int</code> argument.
 * 
 * The representation is exactly the one returned by the
 * <code>Integer.toString</code> method of one argument.
 *
 * @param i an <code>int</code>.
 * @return a string representation of the <code>int</code> argument.
 * @see java.lang.Integer#toString(int, int)
 */
 public static String valueOf(int i) {
 return Integer.toString(i);
 }
 
 /**
 * Returns the string representation of the <code>long</code> argument.
 * 
 * The representation is exactly the one returned by the
 * <code>Long.toString</code> method of one argument.
 *
 * @param l a <code>long</code>.
 * @return a string representation of the <code>long</code> argument.
 * @see java.lang.Long#toString(long)
 */
 public static String valueOf(long l) {
 return Long.toString(l);
 }
 
 /**
 * Returns the string representation of the <code>float</code> argument.
 * 
 * The representation is exactly the one returned by the
 * <code>Float.toString</code> method of one argument.
 *
 * @param f a <code>float</code>.
 * @return a string representation of the <code>float</code> argument.
 * @see java.lang.Float#toString(float)
 */
 public static String valueOf(float f) {
 return Float.toString(f);
 }
 
 /**
 * Returns the string representation of the <code>double</code> argument.
 * 
 * The representation is exactly the one returned by the
 * <code>Double.toString</code> method of one argument.
 *
 * @param d a <code>double</code>.
 * @return a string representation of the <code>double</code> argument.
 * @see java.lang.Double#toString(double)
 */
 public static String valueOf(double d) {
 return Double.toString(d);
 }
 
 /**
 * Returns a canonical representation for the string object.
 * 
 * A pool of strings, initially empty, is maintained privately by the
 * class <code>String</code>.
 * 
 * When the intern method is invoked, if the pool already contains a
 * string equal to this <code>String</code> object as determined by
 * the {@link #equals(Object)} method, then the string from the pool is
 * returned. Otherwise, this <code>String</code> object is added to the
 * pool and a reference to this <code>String</code> object is returned.
 * 
 * It follows that for any two strings <code>s</code> and <code>t</code>,
 * <code>s.intern() == t.intern()</code> is <code>true</code>
 * if and only if <code>s.equals(t)</code> is <code>true</code>.
 * 
 * All literal strings and string-valued constant expressions are
 * interned. String literals are defined in section 3.10.5 of the
 * <cite>The Java™ Language Specification</cite>.
 *
 * @return a string that has the same contents as this string, but is
 * guaranteed to be from a pool of unique strings.
 */
 public native String intern();
 
 /**
 * Seed value used for each alternative hash calculated.
 */
 private static final int HASHING_SEED;
 
 static {
 long nanos = System.nanoTime();
 long now = System.currentTimeMillis();
 int SEED_MATERIAL[] = {
 System.identityHashCode(String.class),
 System.identityHashCode(System.class),
 (int) (nanos >>> 32),
 (int) nanos,
 (int) (now >>> 32),
 (int) now,
 (int) (System.nanoTime() >>> 2)
 };
 
 // Use murmur3 to scramble the seeding material.
 // Inline implementation to avoid loading classes
 int h1 = 0;
 
 // body
 for (int k1 : SEED_MATERIAL) {
 k1 *= 0xcc9e2d51;
 k1 = (k1 << 15) | (k1 >>> 17);
 k1 *= 0x1b873593;
 
 h1 ^= k1;
 h1 = (h1 << 13) | (h1 >>> 19);
 h1 = h1 * 5 + 0xe6546b64;
 }
 
 // tail (always empty, as body is always 32-bit chunks)
 
 // finalization
 
 h1 ^= SEED_MATERIAL.length * 4;
 
 // finalization mix force all bits of a hash block to avalanche
 h1 ^= h1 >>> 16;
 h1 *= 0x85ebca6b;
 h1 ^= h1 >>> 13;
 h1 *= 0xc2b2ae35;
 h1 ^= h1 >>> 16;
 
 HASHING_SEED = h1;
 }
 
 /**
 * Cached value of the alternative hashing algorithm result
 */
 private transient int hash32 = 0;
 
 /**
 * Calculates a 32-bit hash value for this string.
 *
 * @return a 32-bit hash value for this string.
 */
 int hash32() {
 int h = hash32;
 if (0 == h) {
 // harmless data race on hash32 here.
 h = sun.misc.Hashing.murmur3_32(HASHING_SEED, value, 0, value.length);
 
 // ensure result is not zero to avoid recalcing
 h = (0 != h) ? h : 1;
 
 hash32 = h;
 }
 
 return h;
 }
 
 }