/* * Copyright (c) 1994, 2013, 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.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.Objects; import java.util.StringJoiner; import java.util.regex.Matcher; import java.util.regex.Pattern; import java.util.regex.PatternSyntaxException; /** * The {@code String} class represents character strings. All * string literals in Java programs, such as {@code "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 {@code 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 {@code StringBuilder}(or {@code StringBuffer}) * class and its {@code append} method. * String conversions are implemented through the method * {@code toString}, defined by {@code 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 {@code 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 {@code Character} class for * more information). * Index values refer to {@code char} code units, so a supplementary * character uses two positions in a {@code String}. *

The {@code 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., {@code 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[]; /** 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 into an ObjectOutputStream according to * * Object Serialization Specification, Section 6.2, "Stream Elements" */ 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 = "".value; } /** * 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) { if (count < 0) { throw new StringIndexOutOfBoundsException(count); } if (offset <= value.length) { this.value = "".value; return; } } // 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 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) { if (count < 0) { throw new StringIndexOutOfBoundsException(count); } if (offset <= codePoints.length) { this.value = "".value; return; } } // 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: * *

     *     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); 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; } /** * 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 value.length; } /** * Returns {@code true} if, and only if, {@link #length()} is {@code 0}. * * @return {@code true} if {@link #length()} is {@code 0}, otherwise * {@code false} * * @since 1.6 */ public boolean isEmpty() { return value.length == 0; } /** * Returns the {@code char} value at the * specified index. An index ranges from {@code 0} to * {@code length() - 1}. The first {@code char} value of the sequence * is at index {@code 0}, the next at index {@code 1}, * and so on, as for array indexing. * *

If the {@code char} value specified by the index is a * surrogate, the surrogate * value is returned. * * @param index the index of the {@code char} value. * @return the {@code char} value at the specified index of this string. * The first {@code char} value is at index {@code 0}. * @exception IndexOutOfBoundsException if the {@code index} * 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} values * (Unicode code units) and ranges from {@code 0} to * {@link #length()}{@code - 1}. * *

If the {@code char} value specified at the given index * is in the high-surrogate range, the following index is less * than the length of this {@code String}, and the * {@code 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 {@code char} value at the given index is returned. * * @param index the index to the {@code char} values * @return the code point value of the character at the * {@code index} * @exception IndexOutOfBoundsException if the {@code 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 >= 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} values * (Unicode code units) and ranges from {@code 1} to {@link * CharSequence#length() length}. * *

If the {@code char} value at {@code (index - 1)} * is in the low-surrogate range, {@code (index - 2)} is not * negative, and the {@code char} value at {@code (index - * 2)} is in the high-surrogate range, then the * supplementary code point value of the surrogate pair is * returned. If the {@code char} value at {@code 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 {@code 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 >= 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}. The text range begins at the * specified {@code beginIndex} and extends to the * {@code char} at index {@code endIndex - 1}. Thus the * length (in {@code char}s) of the text range is * {@code endIndex-beginIndex}. Unpaired surrogates within * the text range count as one code point each. * * @param beginIndex the index to the first {@code char} of * the text range. * @param endIndex the index after the last {@code char} of * the text range. * @return the number of Unicode code points in the specified text * range * @exception IndexOutOfBoundsException if the * {@code beginIndex} is negative, or {@code endIndex} * is larger than the length of this {@code String}, or * {@code beginIndex} is larger than {@code endIndex}. * @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} that is * offset from the given {@code index} by * {@code codePointOffset} code points. Unpaired surrogates * within the text range given by {@code index} and * {@code 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 {@code String} * @exception IndexOutOfBoundsException if {@code index} * is negative or larger then the length of this * {@code String}, or if {@code codePointOffset} is positive * and the substring starting with {@code index} has fewer * than {@code codePointOffset} code points, * or if {@code codePointOffset} is negative and the substring * before {@code index} has fewer than the absolute value * of {@code codePointOffset} 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}; * the last character to be copied is at index {@code srcEnd-1} * (thus the total number of characters to be copied is * {@code srcEnd-srcBegin}). The characters are copied into the * subarray of {@code dst} starting at index {@code 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 > 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: * *

     *     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 > value.length) { throw new StringIndexOutOfBoundsException(srcEnd); } if (srcBegin > srcEnd) { throw new StringIndexOutOfBoundsException(srcEnd - srcBegin); } Objects.requireNonNull(dst); 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}. This method * synchronizes on the {@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) { return contentEquals((CharSequence)sb); } private boolean nonSyncContentEquals(AbstractStringBuilder sb) { char v1[] = value; char v2[] = sb.getValue(); int n = v1.length; if (n != sb.length()) { return false; } for (int i = 0; i < n; i++) { if (v1[i] != v2[i]) { return false; } } return true; } /** * 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. Note that if the * {@code CharSequence} is a {@code StringBuffer} then the method * synchronizes on it. * * @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) { // Argument is a StringBuffer, StringBuilder if (cs instanceof AbstractStringBuilder) { if (cs instanceof StringBuffer) { synchronized(cs) { return nonSyncContentEquals((AbstractStringBuilder)cs); } } else { return nonSyncContentEquals((AbstractStringBuilder)cs); } } // Argument is a String if (cs instanceof String) { return equals(cs); } // Argument is a generic CharSequence char v1[] = value; int n = v1.length; if (n != cs.length()) { return false; } for (int i = 0; i < n; i++) { if (v1[i] != cs.charAt(i)) { 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.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} object is compared lexicographically to the * character sequence represented by the argument string. The result is * a negative integer if this {@code String} object * lexicographically precedes the argument string. The result is a * positive integer if this {@code String} object lexicographically * follows the argument string. The result is zero if the strings * are equal; {@code compareTo} returns {@code 0} exactly when * the {@link #equals(Object)} method would return {@code 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, {@code compareTo} returns the * difference of the two character values at position {@code 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, * {@code compareTo} returns the difference of the lengths of the * strings -- that is, the value: *
     * this.length()-anotherString.length()
     * 
* * @param anotherString the {@code String} to be compared. * @return the value {@code 0} if the argument string is equal to * this string; a value less than {@code 0} if this string * is lexicographically less than the string argument; and a * value greater than {@code 0} 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} objects as by * {@code 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; } /** Replaces the de-serialized object. */ 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 {@code compareTo} with normalized versions of the strings * where case differences have been eliminated by calling * {@code 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 {@code 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 {@code 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 * {@code String} object to be compared begins at index {@code toffset} * and has length {@code len}. The substring of other to be compared * begins at index {@code ooffset} and has length {@code len}. The * result is {@code 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 {@code true} if the specified subregion of this string * exactly matches the specified subregion of the string argument; * {@code false} 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 {@code String} object is compared to a substring * of the argument {@code other}. The result is {@code true} if these * substrings represent character sequences that are the same, ignoring * case if and only if {@code ignoreCase} is true. The substring of * this {@code String} object to be compared begins at index * {@code toffset} and has length {@code len}. The substring of * {@code other} to be compared begins at index {@code ooffset} and * has length {@code len}. The result is {@code false} if and only if * at least one of the following is true: *

* * @param ignoreCase if {@code 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 {@code true} if the specified subregion of this string * matches the specified subregion of the string argument; * {@code false} otherwise. Whether the matching is exact * or case insensitive depends on the {@code ignoreCase} * 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} if the character sequence represented by the * argument is a prefix of the substring of this object starting * at index {@code toffset}; {@code false} otherwise. * The result is {@code false} if {@code toffset} is * negative or greater than the length of this * {@code 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 = 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} if the character sequence represented by the * argument is a prefix of the character sequence represented by * this string; {@code false} otherwise. * Note also that {@code true} will be returned if the * argument is an empty string or is equal to this * {@code 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 {@code true} if the character sequence represented by the * argument is a suffix of the character sequence represented by * this object; {@code false} otherwise. Note that the * result will be {@code true} if the argument is the * empty string or is equal to this {@code String} 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} object is computed as *
     * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
     * 
* using {@code int} arithmetic, where {@code s[i]} is the * ith character of the string, {@code n} is the length of * the string, and {@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} occurs in the character sequence represented by * this {@code String} object, then the index (in Unicode * code units) of the first such occurrence is returned. For * values of {@code 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 {@code 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 {@code -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 * {@code -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 {@code ch} occurs in the * character sequence represented by this {@code String} * object at an index no smaller than {@code fromIndex}, then * the index of the first such occurrence is returned. For values * of {@code ch} in the range from 0 to 0xFFFF (inclusive), * this is the smallest value k such that: *

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

* There is no restriction on the value of {@code 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: {@code -1} is returned. * *

All indices are specified in {@code 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 {@code fromIndex}, or {@code -1} * 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} 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 {@code 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 {@code -1} is returned. The * {@code 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 * {@code -1} 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} in the range * from 0 to 0xFFFF (inclusive), the index returned is the largest * value k such that: *
     * (this.charAt(k) == ch) {@code &&} (k <= fromIndex)
     * 
* is true. For other values of {@code ch}, it is the * largest value k such that: *
     * (this.codePointAt(k) == ch) {@code &&} (k <= fromIndex)
     * 
* is true. In either case, if no such character occurs in this * string at or before position {@code fromIndex}, then * {@code -1} is returned. * *

All indices are specified in {@code 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 {@code 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 {@code fromIndex}, or {@code -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; 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: *

     * 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 {@code &&} 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, 0, value.length, str.value, 0, str.value.length, fromIndex); } /** * Code shared by String and AbstractStringBuilder 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 fromIndex the index to begin searching from. */ static int indexOf(char[] source, int sourceOffset, int sourceCount, String target, int fromIndex) { return indexOf(source, sourceOffset, sourceCount, target.value, 0, target.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: *

     * 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, 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: *

     * k {@code <=} fromIndex {@code &&} 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, 0, value.length, str.value, 0, str.value.length, fromIndex); } /** * Code shared by String and AbstractStringBuilder 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 fromIndex the index to begin searching from. */ static int lastIndexOf(char[] source, int sourceOffset, int sourceCount, String target, int fromIndex) { return lastIndexOf(source, sourceOffset, sourceCount, target.value, 0, target.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 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 * {@code beginIndex} is negative or larger than the * length of this {@code String} 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 string that is a substring of this string. The * substring begins at the specified {@code beginIndex} and * extends to the character at index {@code endIndex - 1}. * Thus the length of the substring is {@code 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 * {@code beginIndex} is negative, or * {@code endIndex} is larger than the length of * this {@code String} object, or * {@code beginIndex} is larger than * {@code endIndex}. */ 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 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)
* * @apiNote * This method is defined so that the {@code 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 {@code beginIndex} or {@code endIndex} is negative, * if {@code endIndex} is greater than {@code length()}, * or if {@code beginIndex} is greater than {@code endIndex} * * @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}, then this * {@code String} object is returned. Otherwise, a * {@code String} object is returned that represents a character * sequence that is the concatenation of the character sequence * represented by this {@code 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 {@code String} that is concatenated to the end * of this {@code 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; } int len = value.length; char buf[] = Arrays.copyOf(value, len + otherLen); str.getChars(buf, len); return new String(buf, true); } /** * Returns a string resulting from replacing all occurrences of * {@code oldChar} in this string with {@code newChar}. *

* If the character {@code oldChar} does not occur in the * character sequence represented by this {@code String} object, * then a reference to this {@code String} object is returned. * Otherwise, a {@code String} object is returned that * represents a character sequence identical to the character sequence * represented by this {@code String} object, except that every * occurrence of {@code oldChar} is replaced by an occurrence * of {@code 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 {@code oldChar} with {@code newChar}. */ 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 regular expression. * *

An invocation of this method of the form * str{@code .matches(}regex{@code )} 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 {@code 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 {@code s}, false otherwise * @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{@code .replaceFirst(}regex{@code ,} repl{@code )} * 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 ({@code \}) and dollar signs ({@code $}) 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 {@code 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{@code .replaceAll(}regex{@code ,} repl{@code )} * 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 ({@code \}) and dollar signs ({@code $}) 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 {@code 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 * @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. * *

When there is a positive-width match at the beginning of this * string then an empty leading substring is included at the beginning * of the resulting array. A zero-width match at the beginning however * never produces such empty leading substring. * *

The {@code 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 {@code "boo:and:foo"}, for example, yields the * following results with these parameters: * *

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

An invocation of this method of the form * str.{@code split(}regex{@code ,} n{@code )} * 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}(strn) * *
* * * @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 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 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 {@code "boo:and:foo"}, for example, yields the following * results with these expressions: * *

* * * * * * * * *
RegexResult
:{@code { "boo", "and", "foo" }}
o{@code { "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); } /** * Returns a new String composed of copies of the * {@code CharSequence elements} joined together with a copy of * the specified {@code delimiter}. * *
For example, *
{@code
     *     String message = String.join("-", "Java", "is", "cool");
     *     // message returned is: "Java-is-cool"
     * }
* * Note that if an element is null, then {@code "null"} is added. * * @param delimiter the delimiter that separates each element * @param elements the elements to join together. * * @return a new {@code String} that is composed of the {@code elements} * separated by the {@code delimiter} * * @throws NullPointerException If {@code delimiter} or {@code elements} * is {@code null} * * @see java.util.StringJoiner * @since 1.8 */ public static String join(CharSequence delimiter, CharSequence... elements) { Objects.requireNonNull(delimiter); Objects.requireNonNull(elements); // Number of elements not likely worth Arrays.stream overhead. StringJoiner joiner = new StringJoiner(delimiter); for (CharSequence cs: elements) { joiner.add(cs); } return joiner.toString(); } /** * Returns a new {@code String} composed of copies of the * {@code CharSequence elements} joined together with a copy of the * specified {@code delimiter}. * *
For example, *
{@code
     *     List strings = new LinkedList<>();
     *     strings.add("Java");strings.add("is");
     *     strings.add("cool");
     *     String message = String.join(" ", strings);
     *     //message returned is: "Java is cool"
     *
     *     Set strings = new LinkedHashSet<>();
     *     strings.add("Java"); strings.add("is");
     *     strings.add("very"); strings.add("cool");
     *     String message = String.join("-", strings);
     *     //message returned is: "Java-is-very-cool"
     * }
* * Note that if an individual element is {@code null}, then {@code "null"} is added. * * @param delimiter a sequence of characters that is used to separate each * of the {@code elements} in the resulting {@code String} * @param elements an {@code Iterable} that will have its {@code elements} * joined together. * * @return a new {@code String} that is composed from the {@code elements} * argument * * @throws NullPointerException If {@code delimiter} or {@code elements} * is {@code null} * * @see #join(CharSequence,CharSequence...) * @see java.util.StringJoiner * @since 1.8 */ public static String join(CharSequence delimiter, Iterable elements) { Objects.requireNonNull(delimiter); Objects.requireNonNull(elements); StringJoiner joiner = new StringJoiner(delimiter); for (CharSequence cs: elements) { joiner.add(cs); } return joiner.toString(); } /** * Converts all of the characters in this {@code String} to lower * case using the rules of the given {@code 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 * {@code String} may be a different length than the original {@code 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 {@code 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; 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 srcChar == '\u0130') { // LATIN CAPITAL LETTER I WITH DOT ABOVE lowerChar = ConditionalSpecialCasing.toLowerCaseEx(this, i, locale); } else { lowerChar = Character.toLowerCase(srcChar); } if ((lowerChar == Character.ERROR) || (lowerChar >= Character.MIN_SUPPLEMENTARY_CODE_POINT)) { if (lowerChar == Character.ERROR) { 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} to lower * case using the rules of the default locale. This is equivalent to calling * {@code 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, {@code "TITLE".toLowerCase()} in a Turkish locale * returns {@code "t\u005Cu0131tle"}, where '\u005Cu0131' is the * LATIN SMALL LETTER DOTLESS I character. * To obtain correct results for locale insensitive strings, use * {@code toLowerCase(Locale.ROOT)}. *

* @return the {@code String}, 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} to upper * case using the rules of the given {@code 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 * {@code String} may be a different length than the original {@code 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 {@code 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; 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; } /* result may grow, so i+resultOffset is the write location in result */ int resultOffset = 0; char[] result = new char[len]; /* may grow */ /* 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} to upper * case using the rules of the default locale. This method is equivalent to * {@code 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, {@code "title".toUpperCase()} in a Turkish locale * returns {@code "T\u005Cu0130TLE"}, where '\u005Cu0130' is the * LATIN CAPITAL LETTER I WITH DOT ABOVE character. * To obtain correct results for locale insensitive strings, use * {@code toUpperCase(Locale.ROOT)}. *

* @return the {@code String}, converted to uppercase. * @see java.lang.String#toUpperCase(Locale) */ public String toUpperCase() { return toUpperCase(Locale.getDefault()); } /** * Returns a string whose value is this string, with any leading and trailing * whitespace removed. *

* If this {@code String} object represents an empty character * sequence, or the first and last characters of character sequence * represented by this {@code String} object both have codes * greater than {@code '\u005Cu0020'} (the space character), then a * reference to this {@code String} object is returned. *

* Otherwise, if there is no character with a code greater than * {@code '\u005Cu0020'} in the string, then a * {@code String} object representing an empty string is * returned. *

* Otherwise, let k be the index of the first character in the * string whose code is greater than {@code '\u005Cu0020'}, and let * m be the index of the last character in the string whose code * is greater than {@code '\u005Cu0020'}. A {@code String} * object is returned, 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)}. *

* This method may be used to trim whitespace (as defined above) from * the beginning and end of a string. * * @return A string whose value is this string, with any 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 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 * {@code null} argument depends on the conversion. * * @throws java.util.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. * * @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 {@code l} is {@code 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 * {@code null} argument depends on the * conversion. * * @throws java.util.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 * * @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} argument. * * @param obj an {@code Object}. * @return if the argument is {@code null}, then a string equal to * {@code "null"}; otherwise, the value of * {@code 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 {@code char} array * argument. The contents of the character array are copied; subsequent * modification of the character array does not affect the returned * string. * * @param data the character array. * @return a {@code String} that contains the characters of the * character array. */ public static String valueOf(char data[]) { return new String(data); } /** * Returns the string representation of a specific subarray of the * {@code char} array argument. *

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

* The representation is exactly the one returned by the * {@code Integer.toString} method of one argument. * * @param i an {@code int}. * @return a string representation of the {@code 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 {@code long} argument. *

* The representation is exactly the one returned by the * {@code Long.toString} method of one argument. * * @param l a {@code long}. * @return a string representation of the {@code long} 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} argument. *

* The representation is exactly the one returned by the * {@code Float.toString} method of one argument. * * @param f a {@code float}. * @return a string representation of the {@code float} 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} argument. *

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

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

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