/* * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.lang; import java.io.ObjectStreamClass; 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 String class represents character strings. All * string literals in Java programs, such as "abc", 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: *

 *     String str = "abc";
 * 

* is equivalent to: *

 *     char data[] = {'a', 'b', 'c'};
 *     String str = new String(data);
 * 

* Here are some more examples of how strings can be used: *

 *     System.out.println("abc");
 *     String cde = "cde";
 *     System.out.println("abc" + cde);
 *     String c = "abc".substring(2,3);
 *     String d = cde.substring(1, 2);
 * 
*

* The class String 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 StringBuilder(or StringBuffer) * class and its append method. * String conversions are implemented through the method * toString, defined by Object 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 null argument to a constructor * or method in this class will cause a {@link NullPointerException} to be * thrown. * *

A String represents a string in the UTF-16 format * in which supplementary characters are represented by surrogate * pairs (see the section Unicode * Character Representations in the Character class for * more information). * Index values refer to char code units, so a supplementary * character uses two positions in a String. *

The String class provides methods for dealing with * Unicode code points (i.e., characters), in addition to those for * dealing with Unicode code units (i.e., char 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, CharSequence { /** The value is used for character storage. */ private final char value[]; /** The offset is the first index of the storage that is used. */ private final int offset; /** The count is the number of characters in the String. */ private final int count; /** 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: *

     *      TC_STRING (utf String)
     * 
* The String is written by method DataOutput.writeUTF. * 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.offset = 0; this.count = 0; 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) { int size = original.count; char[] originalValue = original.value; char[] v; if (originalValue.length > size) { // The array representing the String is bigger than the new // String itself. Perhaps this constructor is being called // in order to trim the baggage, so make a copy of the array. int off = original.offset; v = Arrays.copyOfRange(originalValue, off, off+size); } else { // The array representing the String is the same // size as the String, so no point in making a copy. v = originalValue; } this.offset = 0; this.count = size; this.value = v; } /** * 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[]) { int size = value.length; this.offset = 0; this.count = size; this.value = Arrays.copyOf(value, size); } /** * 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.offset = 0; this.count = count; this.value = Arrays.copyOfRange(value, offset, offset+count); } /** * Allocates a new {@code String} that contains characters from a subarray * of the Unicode code point 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; this.count = n; this.offset = 0; } /** * 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.offset = 0; this.count = count; 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: * *

     *     c == (char)(((hibyte & 0xff) << 8)
     *                         | (b & 0xff))
     * 
* * @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); char[] v = StringCoding.decode(charsetName, bytes, offset, length); this.offset = 0; this.count = v.length; this.value = v; } /** * 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); char[] v = StringCoding.decode(charset, bytes, offset, length); this.offset = 0; this.count = v.length; this.value = v; } /** * 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); char[] v = StringCoding.decode(bytes, offset, length); this.offset = 0; this.count = v.length; this.value = v; } /** * 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) { String result = buffer.toString(); this.value = result.value; this.count = result.count; this.offset = result.offset; } /** * 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) { String result = builder.toString(); this.value = result.value; this.count = result.count; this.offset = result.offset; } // Package private constructor which shares value array for speed. String(int offset, int count, char value[]) { this.value = value; this.offset = offset; this.count = count; } /** * Returns the length of this string. * The length is equal to the number of Unicode * code units in the string. * * @return the length of the sequence of characters represented by this * object. */ public int length() { return count; } /** * Returns true if, and only if, {@link #length()} is 0. * * @return true if {@link #length()} is 0, otherwise * false * * @since 1.6 */ public boolean isEmpty() { return count == 0; } /** * Returns the char value at the * specified index. An index ranges from 0 to * length() - 1. The first char value of the sequence * is at index 0, the next at index 1, * and so on, as for array indexing. * *

If the char value specified by the index is a * surrogate, the surrogate * value is returned. * * @param index the index of the char value. * @return the char value at the specified index of this string. * The first char value is at index 0. * @exception IndexOutOfBoundsException if the index * argument is negative or not less than the length of this * string. */ public char charAt(int index) { if ((index < 0) || (index >= count)) { throw new StringIndexOutOfBoundsException(index); } return value[index + offset]; } /** * Returns the character (Unicode code point) at the specified * index. The index refers to char values * (Unicode code units) and ranges from 0 to * {@link #length()} - 1. * *

If the char value specified at the given index * is in the high-surrogate range, the following index is less * than the length of this String, and the * char 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 char value at the given index is returned. * * @param index the index to the char values * @return the code point value of the character at the * index * @exception IndexOutOfBoundsException if the index * argument is negative or not less than the length of this * string. * @since 1.5 */ public int codePointAt(int index) { if ((index < 0) || (index >= count)) { throw new StringIndexOutOfBoundsException(index); } return Character.codePointAtImpl(value, offset + index, offset + count); } /** * Returns the character (Unicode code point) before the specified * index. The index refers to char values * (Unicode code units) and ranges from 1 to {@link * CharSequence#length() length}. * *

If the char value at (index - 1) * is in the low-surrogate range, (index - 2) is not * negative, and the char value at (index - * 2) is in the high-surrogate range, then the * supplementary code point value of the surrogate pair is * returned. If the char value at index - * 1 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 index * 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 >= count)) { throw new StringIndexOutOfBoundsException(index); } return Character.codePointBeforeImpl(value, offset + index, offset); } /** * Returns the number of Unicode code points in the specified text * range of this String. The text range begins at the * specified beginIndex and extends to the * char at index endIndex - 1. Thus the * length (in chars) of the text range is * endIndex-beginIndex. Unpaired surrogates within * the text range count as one code point each. * * @param beginIndex the index to the first char of * the text range. * @param endIndex the index after the last char of * the text range. * @return the number of Unicode code points in the specified text * range * @exception IndexOutOfBoundsException if the * beginIndex is negative, or endIndex * is larger than the length of this String, or * beginIndex is larger than endIndex. * @since 1.5 */ public int codePointCount(int beginIndex, int endIndex) { if (beginIndex < 0 || endIndex > count || beginIndex > endIndex) { throw new IndexOutOfBoundsException(); } return Character.codePointCountImpl(value, offset+beginIndex, endIndex-beginIndex); } /** * Returns the index within this String that is * offset from the given index by * codePointOffset code points. Unpaired surrogates * within the text range given by index and * codePointOffset 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 String * @exception IndexOutOfBoundsException if index * is negative or larger then the length of this * String, or if codePointOffset is positive * and the substring starting with index has fewer * than codePointOffset code points, * or if codePointOffset is negative and the substring * before index has fewer than the absolute value * of codePointOffset code points. * @since 1.5 */ public int offsetByCodePoints(int index, int codePointOffset) { if (index < 0 || index > count) { throw new IndexOutOfBoundsException(); } return Character.offsetByCodePointsImpl(value, offset, count, offset+index, codePointOffset) - offset; } /** * 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, offset, dst, dstBegin, count); } /** * Copies characters from this string into the destination character * array. *

* The first character to be copied is at index srcBegin; * the last character to be copied is at index srcEnd-1 * (thus the total number of characters to be copied is * srcEnd-srcBegin). The characters are copied into the * subarray of dst starting at index dstBegin * and ending at index: *

     *     dstbegin + (srcEnd-srcBegin) - 1
     * 
* * @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: * */ public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) { if (srcBegin < 0) { throw new StringIndexOutOfBoundsException(srcBegin); } if (srcEnd > count) { throw new StringIndexOutOfBoundsException(srcEnd); } if (srcBegin > srcEnd) { throw new StringIndexOutOfBoundsException(srcEnd - srcBegin); } System.arraycopy(value, offset + 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: * *

     *     dstbegin + (srcEnd-srcBegin) - 1
     * 
* * @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: * */ @Deprecated public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) { if (srcBegin < 0) { throw new StringIndexOutOfBoundsException(srcBegin); } if (srcEnd > count) { throw new StringIndexOutOfBoundsException(srcEnd); } if (srcBegin > srcEnd) { throw new StringIndexOutOfBoundsException(srcEnd - srcBegin); } int j = dstBegin; int n = offset + srcEnd; int i = offset + 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, offset, count); } /** * 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, offset, count); } /** * 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, offset, count); } /** * 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 = count; if (n == anotherString.count) { char v1[] = value; char v2[] = anotherString.value; int i = offset; int j = anotherString.offset; while (n-- != 0) { if (v1[i++] != v2[j++]) return false; } 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 (count != cs.length()) return false; // Argument is a StringBuffer, StringBuilder if (cs instanceof AbstractStringBuilder) { char v1[] = value; char v2[] = ((AbstractStringBuilder)cs).getValue(); int i = offset; int j = 0; int n = count; while (n-- != 0) { if (v1[i++] != v2[j++]) return false; } return true; } // Argument is a String if (cs.equals(this)) return true; // Argument is a generic CharSequence char v1[] = value; int i = offset; int j = 0; int n = count; while (n-- != 0) { if (v1[i++] != cs.charAt(j++)) return false; } 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: *

* * @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.count == count) && regionMatches(true, 0, anotherString, 0, count); } /** * Compares two strings lexicographically. * The comparison is based on the Unicode value of each character in * the strings. The character sequence represented by this * String object is compared lexicographically to the * character sequence represented by the argument string. The result is * a negative integer if this String object * lexicographically precedes the argument string. The result is a * positive integer if this String object lexicographically * follows the argument string. The result is zero if the strings * are equal; compareTo returns 0 exactly when * the {@link #equals(Object)} method would return true. *

* 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, compareTo returns the * difference of the two character values at position k in * the two string -- that is, the value: *

     * this.charAt(k)-anotherString.charAt(k)
     * 
* If there is no index position at which they differ, then the shorter * string lexicographically precedes the longer string. In this case, * compareTo returns the difference of the lengths of the * strings -- that is, the value: *
     * this.length()-anotherString.length()
     * 
* * @param anotherString the String to be compared. * @return the value 0 if the argument string is equal to * this string; a value less than 0 if this string * is lexicographically less than the string argument; and a * value greater than 0 if this string is * lexicographically greater than the string argument. */ public int compareTo(String anotherString) { int len1 = count; int len2 = anotherString.count; int n = Math.min(len1, len2); char v1[] = value; char v2[] = anotherString.value; int i = offset; int j = anotherString.offset; if (i == j) { int k = i; int lim = n + i; while (k < lim) { char c1 = v1[k]; char c2 = v2[k]; if (c1 != c2) { return c1 - c2; } k++; } } else { while (n-- != 0) { char c1 = v1[i++]; char c2 = v2[j++]; if (c1 != c2) { return c1 - c2; } } } return len1 - len2; } /** * A Comparator that orders String objects as by * compareToIgnoreCase. 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 CASE_INSENSITIVE_ORDER = new CaseInsensitiveComparator(); private static class CaseInsensitiveComparator implements Comparator, 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; } private Object readResolve() { return CASE_INSENSITIVE_ORDER; } } /** * Compares two strings lexicographically, ignoring case * differences. This method returns an integer whose sign is that of * calling compareTo with normalized versions of the strings * where case differences have been eliminated by calling * Character.toLowerCase(Character.toUpperCase(character)) 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 String 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 String 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 * String object to be compared begins at index toffset * and has length len. The substring of other to be compared * begins at index ooffset and has length len. The * result is false if and only if at least one of the following * is true: *

* * @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 true if the specified subregion of this string * exactly matches the specified subregion of the string argument; * false otherwise. */ public boolean regionMatches(int toffset, String other, int ooffset, int len) { char ta[] = value; int to = offset + toffset; char pa[] = other.value; int po = other.offset + ooffset; // Note: toffset, ooffset, or len might be near -1>>>1. if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len) || (ooffset > (long)other.count - 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 String object is compared to a substring * of the argument other. The result is true if these * substrings represent character sequences that are the same, ignoring * case if and only if ignoreCase is true. The substring of * this String object to be compared begins at index * toffset and has length len. The substring of * other to be compared begins at index ooffset and * has length len. The result is false if and only if * at least one of the following is true: *

* * @param ignoreCase if true, 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 true if the specified subregion of this string * matches the specified subregion of the string argument; * false otherwise. Whether the matching is exact * or case insensitive depends on the ignoreCase * argument. */ public boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len) { char ta[] = value; int to = offset + toffset; char pa[] = other.value; int po = other.offset + ooffset; // Note: toffset, ooffset, or len might be near -1>>>1. if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len) || (ooffset > (long)other.count - 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 true if the character sequence represented by the * argument is a prefix of the substring of this object starting * at index toffset; false otherwise. * The result is false if toffset is * negative or greater than the length of this * String object; otherwise the result is the same * as the result of the expression *
     *          this.substring(toffset).startsWith(prefix)
     *          
*/ public boolean startsWith(String prefix, int toffset) { char ta[] = value; int to = offset + toffset; char pa[] = prefix.value; int po = prefix.offset; int pc = prefix.count; // Note: toffset might be near -1>>>1. if ((toffset < 0) || (toffset > count - 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 true if the character sequence represented by the * argument is a prefix of the character sequence represented by * this string; false otherwise. * Note also that true will be returned if the * argument is an empty string or is equal to this * String 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 true if the character sequence represented by the * argument is a suffix of the character sequence represented by * this object; false otherwise. Note that the * result will be true if the argument is the * empty string or is equal to this String object * as determined by the {@link #equals(Object)} method. */ public boolean endsWith(String suffix) { return startsWith(suffix, count - suffix.count); } /** * Returns a hash code for this string. The hash code for a * String object is computed as *
     * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
     * 
* using int arithmetic, where s[i] is the * ith character of the string, n is the length of * the string, and ^ 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 && count > 0) { int off = offset; char val[] = value; int len = count; for (int i = 0; i < len; i++) { h = 31*h + val[off++]; } hash = h; } return h; } /** * Returns the index within this string of the first occurrence of * the specified character. If a character with value * ch occurs in the character sequence represented by * this String object, then the index (in Unicode * code units) of the first such occurrence is returned. For * values of ch in the range from 0 to 0xFFFF * (inclusive), this is the smallest value k such that: *
     * this.charAt(k) == ch
     * 
* is true. For other values of ch, it is the * smallest value k such that: *
     * this.codePointAt(k) == ch
     * 
* is true. In either case, if no such character occurs in this * string, then -1 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 * -1 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 ch occurs in the * character sequence represented by this String * object at an index no smaller than fromIndex, then * the index of the first such occurrence is returned. For values * of ch in the range from 0 to 0xFFFF (inclusive), * this is the smallest value k such that: *

     * (this.charAt(k) == ch) && (k >= fromIndex)
     * 
* is true. For other values of ch, it is the * smallest value k such that: *
     * (this.codePointAt(k) == ch) && (k >= fromIndex)
     * 
* is true. In either case, if no such character occurs in this * string at or after position fromIndex, then * -1 is returned. * *

* There is no restriction on the value of fromIndex. 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: -1 is returned. * *

All indices are specified in char 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 fromIndex, or -1 * if the character does not occur. */ public int indexOf(int ch, int fromIndex) { if (fromIndex < 0) { fromIndex = 0; } else if (fromIndex >= count) { // 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; final int offset = this.offset; final int max = offset + count; for (int i = offset + fromIndex; i < max ; i++) { if (value[i] == ch) { return i - offset; } } 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 int offset = this.offset; final char hi = Character.highSurrogate(ch); final char lo = Character.lowSurrogate(ch); final int max = offset + count - 1; for (int i = offset + fromIndex; i < max; i++) { if (value[i] == hi && value[i+1] == lo) { return i - offset; } } } return -1; } /** * Returns the index within this string of the last occurrence of * the specified character. For values of ch in the * range from 0 to 0xFFFF (inclusive), the index (in Unicode code * units) returned is the largest value k such that: *

     * this.charAt(k) == ch
     * 
* is true. For other values of ch, it is the * largest value k such that: *
     * this.codePointAt(k) == ch
     * 
* is true. In either case, if no such character occurs in this * string, then -1 is returned. The * String 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 * -1 if the character does not occur. */ public int lastIndexOf(int ch) { return lastIndexOf(ch, count - 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 ch in the range * from 0 to 0xFFFF (inclusive), the index returned is the largest * value k such that: *
     * (this.charAt(k) == ch) && (k <= fromIndex)
     * 
* is true. For other values of ch, it is the * largest value k such that: *
     * (this.codePointAt(k) == ch) && (k <= fromIndex)
     * 
* is true. In either case, if no such character occurs in this * string at or before position fromIndex, then * -1 is returned. * *

All indices are specified in char 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 fromIndex. 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 fromIndex, or -1 * 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; final int offset = this.offset; int i = offset + Math.min(fromIndex, count - 1); for (; i >= offset ; i--) { if (value[i] == ch) { return i - offset; } } 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; final int offset = this.offset; char hi = Character.highSurrogate(ch); char lo = Character.lowSurrogate(ch); int i = offset + Math.min(fromIndex, count - 2); for (; i >= offset; i--) { if (value[i] == hi && value[i+1] == lo) { return i - offset; } } } 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: *

     * this.startsWith(str, k)
     * 
* 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: *

     * k >= fromIndex && this.startsWith(str, k)
     * 
* 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, offset, count, str.value, str.offset, str.count, 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: *

     * this.startsWith(str, k)
     * 
* 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, count); } /** * 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: *

     * k <= fromIndex && this.startsWith(str, k)
     * 
* 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, offset, count, str.value, str.offset, str.count, 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: *

     * "unhappy".substring(2) returns "happy"
     * "Harbison".substring(3) returns "bison"
     * "emptiness".substring(9) returns "" (an empty string)
     * 
* * @param beginIndex the beginning index, inclusive. * @return the specified substring. * @exception IndexOutOfBoundsException if * beginIndex is negative or larger than the * length of this String object. */ public String substring(int beginIndex) { return substring(beginIndex, count); } /** * Returns a new string that is a substring of this string. The * substring begins at the specified beginIndex and * extends to the character at index endIndex - 1. * Thus the length of the substring is endIndex-beginIndex. *

* Examples: *

     * "hamburger".substring(4, 8) returns "urge"
     * "smiles".substring(1, 5) returns "mile"
     * 
* * @param beginIndex the beginning index, inclusive. * @param endIndex the ending index, exclusive. * @return the specified substring. * @exception IndexOutOfBoundsException if the * beginIndex is negative, or * endIndex is larger than the length of * this String object, or * beginIndex is larger than * endIndex. */ public String substring(int beginIndex, int endIndex) { if (beginIndex < 0) { throw new StringIndexOutOfBoundsException(beginIndex); } if (endIndex > count) { throw new StringIndexOutOfBoundsException(endIndex); } if (beginIndex > endIndex) { throw new StringIndexOutOfBoundsException(endIndex - beginIndex); } return ((beginIndex == 0) && (endIndex == count)) ? this : new String(offset + beginIndex, endIndex - beginIndex, value); } /** * Returns a new character sequence that is a subsequence of this sequence. * *

An invocation of this method of the form * *

     * str.subSequence(begin, end)
* * behaves in exactly the same way as the invocation * *
     * str.substring(begin, end)
* * This method is defined so that the String 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 beginIndex or endIndex are negative, * if endIndex is greater than length(), * or if beginIndex is greater than startIndex * * @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 0, then this * String object is returned. Otherwise, a new * String object is created, representing a character * sequence that is the concatenation of the character sequence * represented by this String object and the character * sequence represented by the argument string.

* Examples: *

     * "cares".concat("s") returns "caress"
     * "to".concat("get").concat("her") returns "together"
     * 
* * @param str the String that is concatenated to the end * of this String. * @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; } char buf[] = new char[count + otherLen]; getChars(0, count, buf, 0); str.getChars(0, otherLen, buf, count); return new String(0, count + otherLen, buf); } /** * Returns a new string resulting from replacing all occurrences of * oldChar in this string with newChar. *

* If the character oldChar does not occur in the * character sequence represented by this String object, * then a reference to this String object is returned. * Otherwise, a new String object is created that * represents a character sequence identical to the character sequence * represented by this String object, except that every * occurrence of oldChar is replaced by an occurrence * of newChar. *

* Examples: *

     * "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)
     * 
* * @param oldChar the old character. * @param newChar the new character. * @return a string derived from this string by replacing every * occurrence of oldChar with newChar. */ public String replace(char oldChar, char newChar) { if (oldChar != newChar) { int len = count; int i = -1; char[] val = value; /* avoid getfield opcode */ int off = offset; /* avoid getfield opcode */ while (++i < len) { if (val[off + i] == oldChar) { break; } } if (i < len) { char buf[] = new char[len]; for (int j = 0 ; j < i ; j++) { buf[j] = val[off+j]; } while (i < len) { char c = val[off + i]; buf[i] = (c == oldChar) ? newChar : c; i++; } return new String(0, len, buf); } } return this; } /** * Tells whether or not this string matches the given regular expression. * *

An invocation of this method of the form * str.matches(regex) yields exactly the * same result as the expression * *

{@link java.util.regex.Pattern}.{@link * java.util.regex.Pattern#matches(String,CharSequence) * matches}(regex, str)
* * @param regex * the regular expression to which this string is to be matched * * @return true 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 s, false otherwise * @throws NullPointerException if s is null * @since 1.5 */ public boolean contains(CharSequence s) { return indexOf(s.toString()) > -1; } /** * Replaces the first substring of this string that matches the given regular expression with the * given replacement. * *

An invocation of this method of the form * str.replaceFirst(regex, repl) * yields exactly the same result as the expression * *

* {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile * compile}(regex).{@link * java.util.regex.Pattern#matcher(java.lang.CharSequence) * matcher}(str).{@link java.util.regex.Matcher#replaceFirst * replaceFirst}(repl)
* *

* Note that backslashes (\) and dollar signs ($) 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 String * * @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 regular expression with the * given replacement. * *

An invocation of this method of the form * str.replaceAll(regex, repl) * yields exactly the same result as the expression * *

* {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile * compile}(regex).{@link * java.util.regex.Pattern#matcher(java.lang.CharSequence) * matcher}(str).{@link java.util.regex.Matcher#replaceAll * replaceAll}(repl)
* *

* Note that backslashes (\) and dollar signs ($) 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 String * * @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 target or * replacement is null. * @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 * regular expression. * *

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 limit 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 "boo:and:foo", for example, yields the * following results with these parameters: * *

* * * * * * * * * * * * * * * * * * * * * * * *
RegexLimitResult
:2{ "boo", "and:foo" }
:5{ "boo", "and", "foo" }
:-2{ "boo", "and", "foo" }
o5{ "b", "", ":and:f", "", "" }
o-2{ "b", "", ":and:f", "", "" }
o0{ "b", "", ":and:f" }
* *

An invocation of this method of the form * str.split(regex, n) * yields the same result as the expression * *

* {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile * compile}(regex).{@link * java.util.regex.Pattern#split(java.lang.CharSequence,int) * split}(str, n) *
* * * @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 ".$|()[{^?*+\\", or (2)two-char String and the first char is the backslash and the second is not the ascii digit or ascii letter. */ char ch = 0; if (((regex.count == 1 && ".$|()[{^?*+\\".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 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, count)); off = count; 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, count)); // 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 regular expression. * *

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 "boo:and:foo", for example, yields the following * results with these expressions: * *

* * * * * * * * *
RegexResult
:{ "boo", "and", "foo" }
o{ "b", "", ":and:f" }
* * * @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 String to lower * case using the rules of the given Locale. 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 * String may be a different length than the original String. *

* Examples of lowercase mappings are in the following table: * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Language Code of LocaleUpper CaseLower CaseDescription
tr (Turkish)\u0130\u0069capital letter I with dot above -> small letter i
tr (Turkish)\u0049\u0131capital letter I -> small letter dotless i
(all)French Friesfrench frieslowercased all chars in String
(all)capiotacapchi * capthetacapupsil * capsigmaiotachi * thetaupsilon * sigmalowercased all chars in String
* * @param locale use the case transformation rules for this locale * @return the String, 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; /* Now check if there are any characters that need to be changed. */ scan: { for (firstUpper = 0 ; firstUpper < count; ) { char c = value[offset+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[count]; 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, offset, 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 < count; i += srcCount) { srcChar = (int)value[offset+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; xString to lower * case using the rules of the default locale. This is equivalent to calling * toLowerCase(Locale.getDefault()). *

* 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, "TITLE".toLowerCase() in a Turkish locale * returns "t\u005Cu0131tle", where '\u005Cu0131' is the * LATIN SMALL LETTER DOTLESS I character. * To obtain correct results for locale insensitive strings, use * toLowerCase(Locale.ENGLISH). *

* @return the String, converted to lowercase. * @see java.lang.String#toLowerCase(Locale) */ public String toLowerCase() { return toLowerCase(Locale.getDefault()); } /** * Converts all of the characters in this String to upper * case using the rules of the given Locale. 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 * String may be a different length than the original String. *

* Examples of locale-sensitive and 1:M case mappings are in the following table. *

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Language Code of LocaleLower CaseUpper CaseDescription
tr (Turkish)\u0069\u0130small letter i -> capital letter I with dot above
tr (Turkish)\u0131\u0049small letter dotless i -> capital letter I
(all)\u00df\u0053 \u0053small letter sharp s -> two letters: SS
(all)FahrvergnügenFAHRVERGNÜGEN
* @param locale use the case transformation rules for this locale * @return the String, 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; /* Now check if there are any characters that need to be changed. */ scan: { for (firstLower = 0 ; firstLower < count; ) { int c = (int)value[offset+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[count]; /* 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, offset, 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 < count; i += srcCount) { srcChar = (int)value[offset+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; xString to upper * case using the rules of the default locale. This method is equivalent to * toUpperCase(Locale.getDefault()). *

* 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, "title".toUpperCase() in a Turkish locale * returns "T\u005Cu0130TLE", where '\u005Cu0130' is the * LATIN CAPITAL LETTER I WITH DOT ABOVE character. * To obtain correct results for locale insensitive strings, use * toUpperCase(Locale.ENGLISH). *

* @return the String, 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 String object represents an empty character * sequence, or the first and last characters of character sequence * represented by this String object both have codes * greater than '\u0020' (the space character), then a * reference to this String object is returned. *

* Otherwise, if there is no character with a code greater than * '\u0020' in the string, then a new * String 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 '\u0020', and let * m be the index of the last character in the string whose code * is greater than '\u0020'. A new String * 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 * this.substring(km+1). *

* 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 = count; int st = 0; int off = offset; /* avoid getfield opcode */ char[] val = value; /* avoid getfield opcode */ while ((st < len) && (val[off + st] <= ' ')) { st++; } while ((st < len) && (val[off + len - 1] <= ' ')) { len--; } return ((st > 0) || (len < count)) ? 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() { char result[] = new char[count]; getChars(0, count, result, 0); 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 format string * * @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 * The Java™ Virtual Machine Specification. * The behaviour on a * null argument depends on the conversion. * * @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 Details section of the * formatter class specification. * * @throws NullPointerException * If the format is null * * @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 l is null then no localization * is applied. * * @param format * A format string * * @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 * The Java™ Virtual Machine Specification. * The behaviour on a * null argument depends on the conversion. * * @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 Details section of the * formatter class specification * * @throws NullPointerException * If the format is null * * @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 Object argument. * * @param obj an Object. * @return if the argument is null, then a string equal to * "null"; otherwise, the value of * obj.toString() 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 char 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 char 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 * char array argument. *

* The offset argument is the index of the first * character of the subarray. The 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 data the character array. * @param offset the initial offset into the value of the * String. * @param count the length of the value of the String. * @return a string representing the sequence of characters contained * in the subarray of the character array argument. * @exception IndexOutOfBoundsException if offset is * negative, or count is negative, or * offset+count is larger than * data.length. */ 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 String 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 String that contains the characters of the * character array. */ public static String copyValueOf(char data[]) { return copyValueOf(data, 0, data.length); } /** * Returns the string representation of the boolean argument. * * @param b a boolean. * @return if the argument is true, a string equal to * "true" is returned; otherwise, a string equal to * "false" is returned. */ public static String valueOf(boolean b) { return b ? "true" : "false"; } /** * Returns the string representation of the char * argument. * * @param c a char. * @return a string of length 1 containing * as its single character the argument c. */ public static String valueOf(char c) { char data[] = {c}; return new String(0, 1, data); } /** * Returns the string representation of the int argument. *

* The representation is exactly the one returned by the * Integer.toString method of one argument. * * @param i an int. * @return a string representation of the int argument. * @see java.lang.Integer#toString(int, int) */ public static String valueOf(int i) { return Integer.toString(i); } /** * Returns the string representation of the long argument. *

* The representation is exactly the one returned by the * Long.toString method of one argument. * * @param l a long. * @return a string representation of the long argument. * @see java.lang.Long#toString(long) */ public static String valueOf(long l) { return Long.toString(l); } /** * Returns the string representation of the float argument. *

* The representation is exactly the one returned by the * Float.toString method of one argument. * * @param f a float. * @return a string representation of the float argument. * @see java.lang.Float#toString(float) */ public static String valueOf(float f) { return Float.toString(f); } /** * Returns the string representation of the double argument. *

* The representation is exactly the one returned by the * Double.toString method of one argument. * * @param d a double. * @return a string representation of the double 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 String. *

* When the intern method is invoked, if the pool already contains a * string equal to this String object as determined by * the {@link #equals(Object)} method, then the string from the pool is * returned. Otherwise, this String object is added to the * pool and a reference to this String object is returned. *

* It follows that for any two strings s and t, * s.intern() == t.intern() is true * if and only if s.equals(t) is true. *

* All literal strings and string-valued constant expressions are * interned. String literals are defined in section 3.10.5 of the * The Java™ Language Specification. * * @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(); }