Java tutorial
/* * Copyright (c) 1994, 2019, 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.lang.annotation.Native; import java.lang.invoke.MethodHandles; import java.lang.constant.Constable; import java.lang.constant.ConstantDesc; import java.nio.charset.Charset; import java.util.ArrayList; import java.util.Arrays; import java.util.Comparator; import java.util.Formatter; import java.util.List; import java.util.Locale; import java.util.Objects; import java.util.Optional; import java.util.Spliterator; import java.util.StringJoiner; import java.util.function.Function; import java.util.regex.Matcher; import java.util.regex.Pattern; import java.util.regex.PatternSyntaxException; import java.util.stream.Collectors; import java.util.stream.IntStream; import java.util.stream.Stream; import java.util.stream.StreamSupport; import jdk.internal.HotSpotIntrinsicCandidate; import jdk.internal.vm.annotation.Stable; import static java.util.function.Predicate.not; /** * The {@code String} class represents character strings. All * string literals in Java programs, such as {@code "abc"}, are * implemented as instances of this class. * <p> * Strings are constant; their values cannot be changed after they * are created. String buffers support mutable strings. * Because String objects are immutable they can be shared. For example: * <blockquote><pre> * String str = "abc"; * </pre></blockquote><p> * is equivalent to: * <blockquote><pre> * char data[] = {'a', 'b', 'c'}; * String str = new String(data); * </pre></blockquote><p> * Here are some more examples of how strings can be used: * <blockquote><pre> * System.out.println("abc"); * String cde = "cde"; * System.out.println("abc" + cde); * String c = "abc".substring(2, 3); * String d = cde.substring(1, 2); * </pre></blockquote> * <p> * 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. * <p> * The Java language provides special support for the string * concatenation operator ( + ), and for conversion of * other objects to strings. For additional information on string * concatenation and conversion, see <i>The Java™ Language Specification</i>. * * <p> Unless otherwise noted, passing a {@code null} argument to a constructor * or method in this class will cause a {@link NullPointerException} to be * thrown. * * <p>A {@code String} represents a string in the UTF-16 format * in which <em>supplementary characters</em> are represented by <em>surrogate * pairs</em> (see the section <a href="Character.html#unicode">Unicode * Character Representations</a> 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}. * <p>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). * * <p>Unless otherwise noted, methods for comparing Strings do not take locale * into account. The {@link java.text.Collator} class provides methods for * finer-grain, locale-sensitive String comparison. * * @implNote The implementation of the string concatenation operator is left to * the discretion of a Java compiler, as long as the compiler ultimately conforms * to <i>The Java™ Language Specification</i>. For example, the {@code javac} compiler * may implement the operator with {@code StringBuffer}, {@code StringBuilder}, * or {@code java.lang.invoke.StringConcatFactory} depending on the JDK version. The * implementation of string conversion is typically through the method {@code toString}, * defined by {@code Object} and inherited by all classes in Java. * * @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 1.0 * @jls 15.18.1 String Concatenation Operator + */ public final class String implements java.io.Serializable, Comparable<String>, CharSequence, Constable, ConstantDesc { /** * The value is used for character storage. * * @implNote This field is trusted by the VM, and is a subject to * constant folding if String instance is constant. Overwriting this * field after construction will cause problems. * * Additionally, it is marked with {@link Stable} to trust the contents * of the array. No other facility in JDK provides this functionality (yet). * {@link Stable} is safe here, because value is never null. */ @Stable private final byte[] value; /** * The identifier of the encoding used to encode the bytes in * {@code value}. The supported values in this implementation are * * LATIN1 * UTF16 * * @implNote This field is trusted by the VM, and is a subject to * constant folding if String instance is constant. Overwriting this * field after construction will cause problems. */ private final byte coder; /** Cache the hash code for the string */ private int hash; // Default to 0 /** * Cache if the hash has been calculated as actually being zero, enabling * us to avoid recalculating this. */ private boolean hashIsZero; // Default to false; /** use serialVersionUID from JDK 1.0.2 for interoperability */ private static final long serialVersionUID = -6849794470754667710L; /** * If String compaction is disabled, the bytes in {@code value} are * always encoded in UTF16. * * For methods with several possible implementation paths, when String * compaction is disabled, only one code path is taken. * * The instance field value is generally opaque to optimizing JIT * compilers. Therefore, in performance-sensitive place, an explicit * check of the static boolean {@code COMPACT_STRINGS} is done first * before checking the {@code coder} field since the static boolean * {@code COMPACT_STRINGS} would be constant folded away by an * optimizing JIT compiler. The idioms for these cases are as follows. * * For code such as: * * if (coder == LATIN1) { ... } * * can be written more optimally as * * if (coder() == LATIN1) { ... } * * or: * * if (COMPACT_STRINGS && coder == LATIN1) { ... } * * An optimizing JIT compiler can fold the above conditional as: * * COMPACT_STRINGS == true => if (coder == LATIN1) { ... } * COMPACT_STRINGS == false => if (false) { ... } * * @implNote * The actual value for this field is injected by JVM. The static * initialization block is used to set the value here to communicate * that this static final field is not statically foldable, and to * avoid any possible circular dependency during vm initialization. */ static final boolean COMPACT_STRINGS; static { COMPACT_STRINGS = true; } /** * Class String is special cased within the Serialization Stream Protocol. * * A String instance is written into an ObjectOutputStream according to * <a href="{@docRoot}/../specs/serialization/protocol.html#stream-elements"> * Object Serialization Specification, Section 6.2, "Stream Elements"</a> */ 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; this.coder = "".coder; } /** * 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} */ @HotSpotIntrinsicCandidate public String(String original) { this.value = original.value; this.coder = original.coder; 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, 0, value.length, null); } /** * 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 {@code offset} is negative, {@code count} is negative, or * {@code offset} is greater than {@code value.length - count} */ public String(char value[], int offset, int count) { this(value, offset, count, rangeCheck(value, offset, count)); } private static Void rangeCheck(char[] value, int offset, int count) { checkBoundsOffCount(offset, count, value.length); return null; } /** * Allocates a new {@code String} that contains characters from a subarray * of the <a href="Character.html#unicode">Unicode code point</a> array * argument. The {@code offset} argument is the index of the first code * point of the subarray and the {@code count} argument specifies the * length of the subarray. The contents of the subarray are converted to * {@code char}s; subsequent modification of the {@code int} array does not * affect the newly created string. * * @param codePoints * Array that is the source of Unicode code points * * @param offset * The initial offset * * @param count * The length * * @throws IllegalArgumentException * If any invalid Unicode code point is found in {@code * codePoints} * * @throws IndexOutOfBoundsException * If {@code offset} is negative, {@code count} is negative, or * {@code offset} is greater than {@code codePoints.length - count} * * @since 1.5 */ public String(int[] codePoints, int offset, int count) { checkBoundsOffCount(offset, count, codePoints.length); if (count == 0) { this.value = "".value; this.coder = "".coder; return; } if (COMPACT_STRINGS) { byte[] val = StringLatin1.toBytes(codePoints, offset, count); if (val != null) { this.coder = LATIN1; this.value = val; return; } } this.coder = UTF16; this.value = StringUTF16.toBytes(codePoints, offset, count); } /** * Allocates a new {@code String} constructed from a subarray of an array * of 8-bit integer values. * * <p> 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. * * <p> Each {@code byte} in the subarray is converted to a {@code char} as * specified in the {@link #String(byte[],int) String(byte[],int)} constructor. * * @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 {@code offset} is negative, {@code count} is negative, or * {@code offset} is greater than {@code ascii.length - count} * * @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(since = "1.1") public String(byte ascii[], int hibyte, int offset, int count) { checkBoundsOffCount(offset, count, ascii.length); if (count == 0) { this.value = "".value; this.coder = "".coder; return; } if (COMPACT_STRINGS && (byte) hibyte == 0) { this.value = Arrays.copyOfRange(ascii, offset, offset + count); this.coder = LATIN1; } else { hibyte <<= 8; byte[] val = StringUTF16.newBytesFor(count); for (int i = 0; i < count; i++) { StringUTF16.putChar(val, i, hibyte | (ascii[offset++] & 0xff)); } this.value = val; this.coder = UTF16; } } /** * Allocates a new {@code String} containing characters constructed from * an array of 8-bit integer values. Each character <i>c</i> in the * resulting string is constructed from the corresponding component * <i>b</i> in the byte array such that: * * <blockquote><pre> * <b><i>c</i></b> == (char)(((hibyte & 0xff) << 8) * | (<b><i>b</i></b> & 0xff)) * </pre></blockquote> * * @deprecated This method does not properly convert bytes into * characters. As of JDK 1.1, the preferred way to do this is via the * {@code String} constructors that take a {@link * java.nio.charset.Charset}, charset name, or that use the platform's * default charset. * * @param ascii * The bytes to be converted to characters * * @param hibyte * The top 8 bits of each 16-bit Unicode code unit * * @see #String(byte[], int, int, java.lang.String) * @see #String(byte[], int, int, java.nio.charset.Charset) * @see #String(byte[], int, int) * @see #String(byte[], java.lang.String) * @see #String(byte[], java.nio.charset.Charset) * @see #String(byte[]) */ @Deprecated(since = "1.1") public String(byte ascii[], int hibyte) { this(ascii, hibyte, 0, ascii.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. * * <p> 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 {@code offset} is negative, {@code length} is negative, or * {@code offset} is greater than {@code bytes.length - length} * * @since 1.1 */ public String(byte bytes[], int offset, int length, String charsetName) throws UnsupportedEncodingException { if (charsetName == null) throw new NullPointerException("charsetName"); checkBoundsOffCount(offset, length, bytes.length); StringCoding.Result ret = StringCoding.decode(charsetName, bytes, offset, length); this.value = ret.value; this.coder = ret.coder; } /** * 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. * * <p> 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 {@code offset} is negative, {@code length} is negative, or * {@code offset} is greater than {@code bytes.length - length} * * @since 1.6 */ public String(byte bytes[], int offset, int length, Charset charset) { if (charset == null) throw new NullPointerException("charset"); checkBoundsOffCount(offset, length, bytes.length); StringCoding.Result ret = StringCoding.decode(charset, bytes, offset, length); this.value = ret.value; this.coder = ret.coder; } /** * 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. * * <p> 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 1.1 */ 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. * * <p> 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. * * <p> 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 {@code offset} is negative, {@code length} is negative, or * {@code offset} is greater than {@code bytes.length - length} * * @since 1.1 */ public String(byte bytes[], int offset, int length) { checkBoundsOffCount(offset, length, bytes.length); StringCoding.Result ret = StringCoding.decode(bytes, offset, length); this.value = ret.value; this.coder = ret.coder; } /** * 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. * * <p> 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 1.1 */ 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) { this(buffer.toString()); } /** * 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. * * <p> 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(builder, null); } /** * Returns the length of this string. * The length is equal to the number of <a href="Character.html#unicode">Unicode * code units</a> in the string. * * @return the length of the sequence of characters represented by this * object. */ public int length() { return value.length >> coder(); } /** * 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. * * <p>If the {@code char} value specified by the index is a * <a href="Character.html#unicode">surrogate</a>, the surrogate * value is returned. * * @param index the index of the {@code char} 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 (isLatin1()) { return StringLatin1.charAt(value, index); } else { return StringUTF16.charAt(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}. * * <p> 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 (isLatin1()) { checkIndex(index, value.length); return value[index] & 0xff; } int length = value.length >> 1; checkIndex(index, length); return StringUTF16.codePointAt(value, index, 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}. * * <p> 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 >= length()) { throw new StringIndexOutOfBoundsException(index); } if (isLatin1()) { return (value[i] & 0xff); } return StringUTF16.codePointBefore(value, index); } /** * 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 || beginIndex > endIndex || endIndex > length()) { throw new IndexOutOfBoundsException(); } if (isLatin1()) { return endIndex - beginIndex; } return StringUTF16.codePointCount(value, beginIndex, endIndex); } /** * 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 > length()) { throw new IndexOutOfBoundsException(); } return Character.offsetByCodePoints(this, index, codePointOffset); } /** * Copies characters from this string into the destination character * array. * <p> * 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: * <blockquote><pre> * dstBegin + (srcEnd-srcBegin) - 1 * </pre></blockquote> * * @param srcBegin index of the first character in the string * to copy. * @param srcEnd index after the last character in the string * to copy. * @param dst the destination array. * @param dstBegin the start offset in the destination array. * @exception IndexOutOfBoundsException If any of the following * is true: * <ul><li>{@code srcBegin} is negative. * <li>{@code srcBegin} is greater than {@code srcEnd} * <li>{@code srcEnd} is greater than the length of this * string * <li>{@code dstBegin} is negative * <li>{@code dstBegin+(srcEnd-srcBegin)} is larger than * {@code dst.length}</ul> */ public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) { checkBoundsBeginEnd(srcBegin, srcEnd, length()); checkBoundsOffCount(dstBegin, srcEnd - srcBegin, dst.length); if (isLatin1()) { StringLatin1.getChars(value, srcBegin, srcEnd, dst, dstBegin); } else { StringUTF16.getChars(value, srcBegin, srcEnd, dst, dstBegin); } } /** * 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. * * <p> The first character to be copied is at index {@code srcBegin}; the * last character to be copied is at index {@code srcEnd-1}. The total * number of characters to be copied is {@code srcEnd-srcBegin}. The * characters, converted to bytes, are copied into the subarray of {@code * dst} starting at index {@code dstBegin} and ending at index: * * <blockquote><pre> * dstBegin + (srcEnd-srcBegin) - 1 * </pre></blockquote> * * @deprecated This method does not properly convert characters into * bytes. As of JDK 1.1, the preferred way to do this is via the * {@link #getBytes()} method, which uses the platform's default charset. * * @param srcBegin * Index of the first character in the string to copy * * @param srcEnd * Index after the last character in the string to copy * * @param dst * The destination array * * @param dstBegin * The start offset in the destination array * * @throws IndexOutOfBoundsException * If any of the following is true: * <ul> * <li> {@code srcBegin} is negative * <li> {@code srcBegin} is greater than {@code srcEnd} * <li> {@code srcEnd} is greater than the length of this String * <li> {@code dstBegin} is negative * <li> {@code dstBegin+(srcEnd-srcBegin)} is larger than {@code * dst.length} * </ul> */ @Deprecated(since = "1.1") public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) { checkBoundsBeginEnd(srcBegin, srcEnd, length()); Objects.requireNonNull(dst); checkBoundsOffCount(dstBegin, srcEnd - srcBegin, dst.length); if (isLatin1()) { StringLatin1.getBytes(value, srcBegin, srcEnd, dst, dstBegin); } else { StringUTF16.getBytes(value, srcBegin, srcEnd, dst, dstBegin); } } /** * Encodes this {@code String} into a sequence of bytes using the named * charset, storing the result into a new byte array. * * <p> 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 1.1 */ public byte[] getBytes(String charsetName) throws UnsupportedEncodingException { if (charsetName == null) throw new NullPointerException(); return StringCoding.encode(charsetName, coder(), value); } /** * 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. * * <p> 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, coder(), value); } /** * Encodes this {@code String} into a sequence of bytes using the * platform's default charset, storing the result into a new byte array. * * <p> 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 1.1 */ public byte[] getBytes() { return StringCoding.encode(coder(), value); } /** * 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. * * <p>For finer-grained String comparison, refer to * {@link java.text.Collator}. * * @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 aString = (String) anObject; if (!COMPACT_STRINGS || this.coder == aString.coder) { return StringLatin1.equals(value, aString.value); } } 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}. * * <p>For finer-grained String comparison, refer to * {@link java.text.Collator}. * * @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) { int len = length(); if (len != sb.length()) { return false; } byte v1[] = value; byte v2[] = sb.getValue(); byte coder = coder(); if (coder == sb.getCoder()) { int n = v1.length; for (int i = 0; i < n; i++) { if (v1[i] != v2[i]) { return false; } } } else { if (coder != LATIN1) { // utf16 str and latin1 abs can never be "equal" return false; } return StringUTF16.contentEquals(v1, v2, len); } 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. * * <p>For finer-grained String comparison, refer to * {@link java.text.Collator}. * * @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 int n = cs.length(); if (n != length()) { return false; } byte[] val = this.value; if (isLatin1()) { for (int i = 0; i < n; i++) { if ((val[i] & 0xff) != cs.charAt(i)) { return false; } } } else { if (!StringUTF16.contentEquals(val, cs, n)) { 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. * * <p> Two characters {@code c1} and {@code c2} are considered the same * ignoring case if at least one of the following is true: * <ul> * <li> The two characters are the same (as compared by the * {@code ==} operator) * <li> Calling {@code Character.toLowerCase(Character.toUpperCase(char))} * on each character produces the same result * </ul> * * <p>Note that this method does <em>not</em> take locale into account, and * will result in unsatisfactory results for certain locales. The * {@link java.text.Collator} class provides locale-sensitive comparison. * * @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.length() == length()) && regionMatches(true, 0, anotherString, 0, 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}. * <p> * 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 <i>k</i> be the smallest such index; then the string * whose character at position <i>k</i> has the smaller value, as * determined by using the {@code <} 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: * <blockquote><pre> * this.charAt(k)-anotherString.charAt(k) * </pre></blockquote> * If there is no index position at which they differ, then the shorter * string lexicographically precedes the longer string. In this case, * {@code compareTo} returns the difference of the lengths of the * strings -- that is, the value: * <blockquote><pre> * this.length()-anotherString.length() * </pre></blockquote> * * <p>For finer-grained String comparison, refer to * {@link java.text.Collator}. * * @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) { byte v1[] = value; byte v2[] = anotherString.value; byte coder = coder(); if (coder == anotherString.coder()) { return coder == LATIN1 ? StringLatin1.compareTo(v1, v2) : StringUTF16.compareTo(v1, v2); } return coder == LATIN1 ? StringLatin1.compareToUTF16(v1, v2) : StringUTF16.compareToLatin1(v1, v2); } /** * A Comparator that orders {@code String} objects as by * {@code compareToIgnoreCase}. This comparator is serializable. * <p> * Note that this Comparator does <em>not</em> take locale into account, * and will result in an unsatisfactory ordering for certain locales. * The {@link java.text.Collator} class provides locale-sensitive comparison. * * @see java.text.Collator * @since 1.2 */ public static final Comparator<String> CASE_INSENSITIVE_ORDER = new CaseInsensitiveComparator(); private static class CaseInsensitiveComparator implements Comparator<String>, java.io.Serializable { // use serialVersionUID from JDK 1.2.2 for interoperability private static final long serialVersionUID = 8575799808933029326L; public int compare(String s1, String s2) { byte v1[] = s1.value; byte v2[] = s2.value; byte coder = s1.coder(); if (coder == s2.coder()) { return coder == LATIN1 ? StringLatin1.compareToCI(v1, v2) : StringUTF16.compareToCI(v1, v2); } return coder == LATIN1 ? StringLatin1.compareToCI_UTF16(v1, v2) : StringUTF16.compareToCI_Latin1(v1, v2); } /** 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. * <p> * Note that this method does <em>not</em> take locale into account, * and will result in an unsatisfactory ordering for certain locales. * The {@link java.text.Collator} class provides locale-sensitive comparison. * * @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 * @since 1.2 */ public int compareToIgnoreCase(String str) { return CASE_INSENSITIVE_ORDER.compare(this, str); } /** * Tests if two string regions are equal. * <p> * 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: * <ul><li>{@code toffset} is negative. * <li>{@code ooffset} is negative. * <li>{@code toffset+len} is greater than the length of this * {@code String} object. * <li>{@code ooffset+len} is greater than the length of the other * argument. * <li>There is some nonnegative integer <i>k</i> less than {@code len} * such that: * {@code this.charAt(toffset + }<i>k</i>{@code ) != other.charAt(ooffset + } * <i>k</i>{@code )} * </ul> * * <p>Note that this method does <em>not</em> take locale into account. The * {@link java.text.Collator} class provides locale-sensitive comparison. * * @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) { byte tv[] = value; byte ov[] = other.value; // Note: toffset, ooffset, or len might be near -1>>>1. if ((ooffset < 0) || (toffset < 0) || (toffset > (long) length() - len) || (ooffset > (long) other.length() - len)) { return false; } byte coder = coder(); if (coder == other.coder()) { if (!isLatin1() && (len > 0)) { toffset = toffset << 1; ooffset = ooffset << 1; len = len << 1; } while (len-- > 0) { if (tv[toffset++] != ov[ooffset++]) { return false; } } } else { if (coder == LATIN1) { while (len-- > 0) { if (StringLatin1.getChar(tv, toffset++) != StringUTF16.getChar(ov, ooffset++)) { return false; } } } else { while (len-- > 0) { if (StringUTF16.getChar(tv, toffset++) != StringLatin1.getChar(ov, ooffset++)) { return false; } } } } return true; } /** * Tests if two string regions are equal. * <p> * 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: * <ul><li>{@code toffset} is negative. * <li>{@code ooffset} is negative. * <li>{@code toffset+len} is greater than the length of this * {@code String} object. * <li>{@code ooffset+len} is greater than the length of the other * argument. * <li>{@code ignoreCase} is {@code false} and there is some nonnegative * integer <i>k</i> less than {@code len} such that: * <blockquote><pre> * this.charAt(toffset+k) != other.charAt(ooffset+k) * </pre></blockquote> * <li>{@code ignoreCase} is {@code true} and there is some nonnegative * integer <i>k</i> less than {@code len} such that: * <blockquote><pre> * Character.toLowerCase(Character.toUpperCase(this.charAt(toffset+k))) != Character.toLowerCase(Character.toUpperCase(other.charAt(ooffset+k))) * </pre></blockquote> * </ul> * * <p>Note that this method does <em>not</em> take locale into account, * and will result in unsatisfactory results for certain locales when * {@code ignoreCase} is {@code true}. The {@link java.text.Collator} class * provides locale-sensitive comparison. * * @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) { if (!ignoreCase) { return regionMatches(toffset, other, ooffset, len); } // Note: toffset, ooffset, or len might be near -1>>>1. if ((ooffset < 0) || (toffset < 0) || (toffset > (long) length() - len) || (ooffset > (long) other.length() - len)) { return false; } byte tv[] = value; byte ov[] = other.value; byte coder = coder(); if (coder == other.coder()) { return coder == LATIN1 ? StringLatin1.regionMatchesCI(tv, toffset, ov, ooffset, len) : StringUTF16.regionMatchesCI(tv, toffset, ov, ooffset, len); } return coder == LATIN1 ? StringLatin1.regionMatchesCI_UTF16(tv, toffset, ov, ooffset, len) : StringUTF16.regionMatchesCI_Latin1(tv, toffset, ov, ooffset, len); } /** * 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 * <pre> * this.substring(toffset).startsWith(prefix) * </pre> */ public boolean startsWith(String prefix, int toffset) { // Note: toffset might be near -1>>>1. if (toffset < 0 || toffset > length() - prefix.length()) { return false; } byte ta[] = value; byte pa[] = prefix.value; int po = 0; int pc = pa.length; byte coder = coder(); if (coder == prefix.coder()) { int to = (coder == LATIN1) ? toffset : toffset << 1; while (po < pc) { if (ta[to++] != pa[po++]) { return false; } } } else { if (coder == LATIN1) { // && pcoder == UTF16 return false; } // coder == UTF16 && pcoder == LATIN1) while (po < pc) { if (StringUTF16.getChar(ta, toffset++) != (pa[po++] & 0xff)) { 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, length() - suffix.length()); } /** * Returns a hash code for this string. The hash code for a * {@code String} object is computed as * <blockquote><pre> * s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1] * </pre></blockquote> * using {@code int} arithmetic, where {@code s[i]} is the * <i>i</i>th 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() { // The hash or hashIsZero fields are subject to a benign data race, // making it crucial to ensure that any observable result of the // calculation in this method stays correct under any possible read of // these fields. Necessary restrictions to allow this to be correct // without explicit memory fences or similar concurrency primitives is // that we can ever only write to one of these two fields for a given // String instance, and that the computation is idempotent and derived // from immutable state int h = hash; if (h == 0 && !hashIsZero) { h = isLatin1() ? StringLatin1.hashCode(value) : StringUTF16.hashCode(value); if (h == 0) { hashIsZero = true; } else { 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 <i>k</i> such that: * <blockquote><pre> * this.charAt(<i>k</i>) == ch * </pre></blockquote> * is true. For other values of {@code ch}, it is the * smallest value <i>k</i> such that: * <blockquote><pre> * this.codePointAt(<i>k</i>) == ch * </pre></blockquote> * 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. * <p> * 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 <i>k</i> such that: * <blockquote><pre> * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex) * </pre></blockquote> * is true. For other values of {@code ch}, it is the * smallest value <i>k</i> such that: * <blockquote><pre> * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> >= fromIndex) * </pre></blockquote> * is true. In either case, if no such character occurs in this * string at or after position {@code fromIndex}, then * {@code -1} is returned. * * <p> * 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. * * <p>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) { return isLatin1() ? StringLatin1.indexOf(value, ch, fromIndex) : StringUTF16.indexOf(value, ch, fromIndex); } /** * 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 <i>k</i> such that: * <blockquote><pre> * this.charAt(<i>k</i>) == ch * </pre></blockquote> * is true. For other values of {@code ch}, it is the * largest value <i>k</i> such that: * <blockquote><pre> * this.codePointAt(<i>k</i>) == ch * </pre></blockquote> * 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, 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 <i>k</i> such that: * <blockquote><pre> * (this.charAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex) * </pre></blockquote> * is true. For other values of {@code ch}, it is the * largest value <i>k</i> such that: * <blockquote><pre> * (this.codePointAt(<i>k</i>) == ch) {@code &&} (<i>k</i> <= fromIndex) * </pre></blockquote> * is true. In either case, if no such character occurs in this * string at or before position {@code fromIndex}, then * {@code -1} is returned. * * <p>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) { return isLatin1() ? StringLatin1.lastIndexOf(value, ch, fromIndex) : StringUTF16.lastIndexOf(value, ch, fromIndex); } /** * Returns the index within this string of the first occurrence of the * specified substring. * * <p>The returned index is the smallest value {@code k} for which: * <pre>{@code * this.startsWith(str, k) * }</pre> * If no such value of {@code 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) { byte coder = coder(); if (coder == str.coder()) { return isLatin1() ? StringLatin1.indexOf(value, str.value) : StringUTF16.indexOf(value, str.value); } if (coder == LATIN1) { // str.coder == UTF16 return -1; } return StringUTF16.indexOfLatin1(value, str.value); } /** * Returns the index within this string of the first occurrence of the * specified substring, starting at the specified index. * * <p>The returned index is the smallest value {@code k} for which: * <pre>{@code * k >= Math.min(fromIndex, this.length()) && * this.startsWith(str, k) * }</pre> * If no such value of {@code 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, coder(), length(), str, 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 src the characters being searched. * @param srcCoder the coder of the source string. * @param srcCount length of the source string. * @param tgtStr the characters being searched for. * @param fromIndex the index to begin searching from. */ static int indexOf(byte[] src, byte srcCoder, int srcCount, String tgtStr, int fromIndex) { byte[] tgt = tgtStr.value; byte tgtCoder = tgtStr.coder(); int tgtCount = tgtStr.length(); if (fromIndex >= srcCount) { return (tgtCount == 0 ? srcCount : -1); } if (fromIndex < 0) { fromIndex = 0; } if (tgtCount == 0) { return fromIndex; } if (tgtCount > srcCount) { return -1; } if (srcCoder == tgtCoder) { return srcCoder == LATIN1 ? StringLatin1.indexOf(src, srcCount, tgt, tgtCount, fromIndex) : StringUTF16.indexOf(src, srcCount, tgt, tgtCount, fromIndex); } if (srcCoder == LATIN1) { // && tgtCoder == UTF16 return -1; } // srcCoder == UTF16 && tgtCoder == LATIN1) { return StringUTF16.indexOfLatin1(src, srcCount, tgt, tgtCount, fromIndex); } /** * 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()}. * * <p>The returned index is the largest value {@code k} for which: * <pre>{@code * this.startsWith(str, k) * }</pre> * If no such value of {@code 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, length()); } /** * Returns the index within this string of the last occurrence of the * specified substring, searching backward starting at the specified index. * * <p>The returned index is the largest value {@code k} for which: * <pre>{@code * k <= Math.min(fromIndex, this.length()) && * this.startsWith(str, k) * }</pre> * If no such value of {@code 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, coder(), length(), str, 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 src the characters being searched. * @param srcCoder coder handles the mapping between bytes/chars * @param srcCount count of the source string. * @param tgt the characters being searched for. * @param fromIndex the index to begin searching from. */ static int lastIndexOf(byte[] src, byte srcCoder, int srcCount, String tgtStr, int fromIndex) { byte[] tgt = tgtStr.value; byte tgtCoder = tgtStr.coder(); int tgtCount = tgtStr.length(); /* * Check arguments; return immediately where possible. For * consistency, don't check for null str. */ int rightIndex = srcCount - tgtCount; if (fromIndex > rightIndex) { fromIndex = rightIndex; } if (fromIndex < 0) { return -1; } /* Empty string always matches. */ if (tgtCount == 0) { return fromIndex; } if (srcCoder == tgtCoder) { return srcCoder == LATIN1 ? StringLatin1.lastIndexOf(src, srcCount, tgt, tgtCount, fromIndex) : StringUTF16.lastIndexOf(src, srcCount, tgt, tgtCount, fromIndex); } if (srcCoder == LATIN1) { // && tgtCoder == UTF16 return -1; } // srcCoder == UTF16 && tgtCoder == LATIN1 return StringUTF16.lastIndexOfLatin1(src, srcCount, tgt, tgtCount, fromIndex); } /** * 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. <p> * Examples: * <blockquote><pre> * "unhappy".substring(2) returns "happy" * "Harbison".substring(3) returns "bison" * "emptiness".substring(9) returns "" (an empty string) * </pre></blockquote> * * @param beginIndex the beginning index, inclusive. * @return the specified substring. * @exception IndexOutOfBoundsException if * {@code beginIndex} 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 = length() - beginIndex; if (subLen < 0) { throw new StringIndexOutOfBoundsException(subLen); } if (beginIndex == 0) { return this; } return isLatin1() ? StringLatin1.newString(value, beginIndex, subLen) : StringUTF16.newString(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}. * <p> * Examples: * <blockquote><pre> * "hamburger".substring(4, 8) returns "urge" * "smiles".substring(1, 5) returns "mile" * </pre></blockquote> * * @param beginIndex the beginning index, inclusive. * @param endIndex the ending index, exclusive. * @return the specified substring. * @exception IndexOutOfBoundsException if the * {@code beginIndex} 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) { int length = length(); checkBoundsBeginEnd(beginIndex, endIndex, length); int subLen = endIndex - beginIndex; if (beginIndex == 0 && endIndex == length) { return this; } return isLatin1() ? StringLatin1.newString(value, beginIndex, subLen) : StringUTF16.newString(value, beginIndex, subLen); } /** * Returns a character sequence that is a subsequence of this sequence. * * <p> An invocation of this method of the form * * <blockquote><pre> * str.subSequence(begin, end)</pre></blockquote> * * behaves in exactly the same way as the invocation * * <blockquote><pre> * str.substring(begin, end)</pre></blockquote> * * @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. * <p> * 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.<p> * Examples: * <blockquote><pre> * "cares".concat("s") returns "caress" * "to".concat("get").concat("her") returns "together" * </pre></blockquote> * * @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) { if (str.isEmpty()) { return this; } return StringConcatHelper.simpleConcat(this, str); } /** * Returns a string resulting from replacing all occurrences of * {@code oldChar} in this string with {@code newChar}. * <p> * 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}. * <p> * Examples: * <blockquote><pre> * "mesquite in your cellar".replace('e', 'o') * returns "mosquito in your collar" * "the war of baronets".replace('r', 'y') * returns "the way of bayonets" * "sparring with a purple porpoise".replace('p', 't') * returns "starring with a turtle tortoise" * "JonL".replace('q', 'x') returns "JonL" (no change) * </pre></blockquote> * * @param oldChar the old character. * @param newChar the new character. * @return a string derived from this string by replacing every * occurrence of {@code oldChar} with {@code newChar}. */ public String replace(char oldChar, char newChar) { if (oldChar != newChar) { String ret = isLatin1() ? StringLatin1.replace(value, oldChar, newChar) : StringUTF16.replace(value, oldChar, newChar); if (ret != null) { return ret; } } return this; } /** * Tells whether or not this string matches the given <a * href="../util/regex/Pattern.html#sum">regular expression</a>. * * <p> An invocation of this method of the form * <i>str</i>{@code .matches(}<i>regex</i>{@code )} yields exactly the * same result as the expression * * <blockquote> * {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#matches(String,CharSequence) * matches(<i>regex</i>, <i>str</i>)} * </blockquote> * * @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()) >= 0; } /** * Replaces the first substring of this string that matches the given <a * href="../util/regex/Pattern.html#sum">regular expression</a> with the * given replacement. * * <p> An invocation of this method of the form * <i>str</i>{@code .replaceFirst(}<i>regex</i>{@code ,} <i>repl</i>{@code )} * yields exactly the same result as the expression * * <blockquote> * <code> * {@link java.util.regex.Pattern}.{@link * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link * java.util.regex.Matcher#replaceFirst replaceFirst}(<i>repl</i>) * </code> * </blockquote> * *<p> * 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 <a * href="../util/regex/Pattern.html#sum">regular expression</a> with the * given replacement. * * <p> An invocation of this method of the form * <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )} * yields exactly the same result as the expression * * <blockquote> * <code> * {@link java.util.regex.Pattern}.{@link * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link * java.util.regex.Matcher#replaceAll replaceAll}(<i>repl</i>) * </code> * </blockquote> * *<p> * 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) { String trgtStr = target.toString(); String replStr = replacement.toString(); int thisLen = length(); int trgtLen = trgtStr.length(); int replLen = replStr.length(); if (trgtLen > 0) { if (trgtLen == 1 && replLen == 1) { return replace(trgtStr.charAt(0), replStr.charAt(0)); } boolean thisIsLatin1 = this.isLatin1(); boolean trgtIsLatin1 = trgtStr.isLatin1(); boolean replIsLatin1 = replStr.isLatin1(); String ret = (thisIsLatin1 && trgtIsLatin1 && replIsLatin1) ? StringLatin1.replace(value, thisLen, trgtStr.value, trgtLen, replStr.value, replLen) : StringUTF16.replace(value, thisLen, thisIsLatin1, trgtStr.value, trgtLen, trgtIsLatin1, replStr.value, replLen, replIsLatin1); if (ret != null) { return ret; } return this; } else { // trgtLen == 0 int resultLen; try { resultLen = Math.addExact(thisLen, Math.multiplyExact(Math.addExact(thisLen, 1), replLen)); } catch (ArithmeticException ignored) { throw new OutOfMemoryError(); } StringBuilder sb = new StringBuilder(resultLen); sb.append(replStr); for (int i = 0; i < thisLen; ++i) { sb.append(charAt(i)).append(replStr); } return sb.toString(); } } /** * Splits this string around matches of the given * <a href="../util/regex/Pattern.html#sum">regular expression</a>. * * <p> 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. * * <p> 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. * * <p> The {@code limit} parameter controls the number of times the * pattern is applied and therefore affects the length of the resulting * array. * <ul> * <li><p> * If the <i>limit</i> is positive then the pattern will be applied * at most <i>limit</i> - 1 times, the array's length will be * no greater than <i>limit</i>, and the array's last entry will contain * all input beyond the last matched delimiter.</p></li> * * <li><p> * If the <i>limit</i> 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.</p></li> * * <li><p> * If the <i>limit</i> is negative then the pattern will be applied * as many times as possible and the array can have any length.</p></li> * </ul> * * <p> The string {@code "boo:and:foo"}, for example, yields the * following results with these parameters: * * <blockquote><table class="plain"> * <caption style="display:none">Split example showing regex, limit, and result</caption> * <thead> * <tr> * <th scope="col">Regex</th> * <th scope="col">Limit</th> * <th scope="col">Result</th> * </tr> * </thead> * <tbody> * <tr><th scope="row" rowspan="3" style="font-weight:normal">:</th> * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">2</th> * <td>{@code { "boo", "and:foo" }}</td></tr> * <tr><!-- : --> * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th> * <td>{@code { "boo", "and", "foo" }}</td></tr> * <tr><!-- : --> * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th> * <td>{@code { "boo", "and", "foo" }}</td></tr> * <tr><th scope="row" rowspan="3" style="font-weight:normal">o</th> * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">5</th> * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr> * <tr><!-- o --> * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">-2</th> * <td>{@code { "b", "", ":and:f", "", "" }}</td></tr> * <tr><!-- o --> * <th scope="row" style="font-weight:normal; text-align:right; padding-right:1em">0</th> * <td>{@code { "b", "", ":and:f" }}</td></tr> * </tbody> * </table></blockquote> * * <p> An invocation of this method of the form * <i>str.</i>{@code split(}<i>regex</i>{@code ,} <i>n</i>{@code )} * yields the same result as the expression * * <blockquote> * <code> * {@link java.util.regex.Pattern}.{@link * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link * java.util.regex.Pattern#split(java.lang.CharSequence,int) split}(<i>str</i>, <i>n</i>) * </code> * </blockquote> * * * @param regex * the delimiting regular expression * * @param limit * the result threshold, as described above * * @return the array of strings computed by splitting this string * around matches of the given regular expression * * @throws PatternSyntaxException * if the regular expression's syntax is invalid * * @see java.util.regex.Pattern * * @since 1.4 * @spec JSR-51 */ public String[] split(String regex, int limit) { /* fastpath if the regex is a (1)one-char String and this character is not one of the RegEx's meta characters ".$|()[{^?*+\\", or (2)two-char String and the first char is the backslash and the second is not the ascii digit or ascii letter. */ char ch = 0; if (((regex.length() == 1 && ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) || (regex.length() == 2 && regex.charAt(0) == '\\' && (((ch = regex.charAt(1)) - '0') | ('9' - ch)) < 0 && ((ch - 'a') | ('z' - ch)) < 0 && ((ch - 'A') | ('Z' - ch)) < 0)) && (ch < Character.MIN_HIGH_SURROGATE || ch > Character.MAX_LOW_SURROGATE)) { int off = 0; int next = 0; boolean limited = limit > 0; ArrayList<String> list = new ArrayList<>(); while ((next = indexOf(ch, off)) != -1) { if (!limited || list.size() < limit - 1) { list.add(substring(off, next)); off = next + 1; } else { // last one //assert (list.size() == limit - 1); int last = length(); list.add(substring(off, last)); off = last; 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, length())); // Construct result int resultSize = list.size(); if (limit == 0) { while (resultSize > 0 && list.get(resultSize - 1).isEmpty()) { resultSize--; } } String[] result = new String[resultSize]; return list.subList(0, resultSize).toArray(result); } return Pattern.compile(regex).split(this, limit); } /** * Splits this string around matches of the given <a * href="../util/regex/Pattern.html#sum">regular expression</a>. * * <p> 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. * * <p> The string {@code "boo:and:foo"}, for example, yields the following * results with these expressions: * * <blockquote><table class="plain"> * <caption style="display:none">Split examples showing regex and result</caption> * <thead> * <tr> * <th scope="col">Regex</th> * <th scope="col">Result</th> * </tr> * </thead> * <tbody> * <tr><th scope="row" style="text-weight:normal">:</th> * <td>{@code { "boo", "and", "foo" }}</td></tr> * <tr><th scope="row" style="text-weight:normal">o</th> * <td>{@code { "b", "", ":and:f" }}</td></tr> * </tbody> * </table></blockquote> * * * @param regex * the delimiting regular expression * * @return the array of strings computed by splitting this string * around matches of the given regular expression * * @throws PatternSyntaxException * if the regular expression's syntax is invalid * * @see java.util.regex.Pattern * * @since 1.4 * @spec JSR-51 */ public String[] split(String regex) { return split(regex, 0); } /** * Returns a new String composed of copies of the * {@code CharSequence elements} joined together with a copy of * the specified {@code delimiter}. * * <blockquote>For example, * <pre>{@code * String message = String.join("-", "Java", "is", "cool"); * // message returned is: "Java-is-cool" * }</pre></blockquote> * * 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}. * * <blockquote>For example, * <pre>{@code * List<String> strings = List.of("Java", "is", "cool"); * String message = String.join(" ", strings); * //message returned is: "Java is cool" * * Set<String> strings = * new LinkedHashSet<>(List.of("Java", "is", "very", "cool")); * String message = String.join("-", strings); * //message returned is: "Java-is-very-cool" * }</pre></blockquote> * * 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<? extends CharSequence> 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}. * <p> * Examples of lowercase mappings are in the following table: * <table class="plain"> * <caption style="display:none">Lowercase mapping examples showing language code of locale, upper case, lower case, and description</caption> * <thead> * <tr> * <th scope="col">Language Code of Locale</th> * <th scope="col">Upper Case</th> * <th scope="col">Lower Case</th> * <th scope="col">Description</th> * </tr> * </thead> * <tbody> * <tr> * <td>tr (Turkish)</td> * <th scope="row" style="font-weight:normal; text-align:left">\u0130</th> * <td>\u0069</td> * <td>capital letter I with dot above -> small letter i</td> * </tr> * <tr> * <td>tr (Turkish)</td> * <th scope="row" style="font-weight:normal; text-align:left">\u0049</th> * <td>\u0131</td> * <td>capital letter I -> small letter dotless i </td> * </tr> * <tr> * <td>(all)</td> * <th scope="row" style="font-weight:normal; text-align:left">French Fries</th> * <td>french fries</td> * <td>lowercased all chars in String</td> * </tr> * <tr> * <td>(all)</td> * <th scope="row" style="font-weight:normal; text-align:left"> * ΙΧΘΥΣ</th> * <td>ιχθυσ</td> * <td>lowercased all chars in String</td> * </tr> * </tbody> * </table> * * @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) { return isLatin1() ? StringLatin1.toLowerCase(this, value, locale) : StringUTF16.toLowerCase(this, value, locale); } /** * 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())}. * <p> * <b>Note:</b> 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}. * <p> * Examples of locale-sensitive and 1:M case mappings are in the following table. * * <table class="plain"> * <caption style="display:none">Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.</caption> * <thead> * <tr> * <th scope="col">Language Code of Locale</th> * <th scope="col">Lower Case</th> * <th scope="col">Upper Case</th> * <th scope="col">Description</th> * </tr> * </thead> * <tbody> * <tr> * <td>tr (Turkish)</td> * <th scope="row" style="font-weight:normal; text-align:left">\u0069</th> * <td>\u0130</td> * <td>small letter i -> capital letter I with dot above</td> * </tr> * <tr> * <td>tr (Turkish)</td> * <th scope="row" style="font-weight:normal; text-align:left">\u0131</th> * <td>\u0049</td> * <td>small letter dotless i -> capital letter I</td> * </tr> * <tr> * <td>(all)</td> * <th scope="row" style="font-weight:normal; text-align:left">\u00df</th> * <td>\u0053 \u0053</td> * <td>small letter sharp s -> two letters: SS</td> * </tr> * <tr> * <td>(all)</td> * <th scope="row" style="font-weight:normal; text-align:left">Fahrvergnügen</th> * <td>FAHRVERGNÜGEN</td> * <td></td> * </tr> * </tbody> * </table> * @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) { return isLatin1() ? StringLatin1.toUpperCase(this, value, locale) : StringUTF16.toUpperCase(this, value, locale); } /** * 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())}. * <p> * <b>Note:</b> 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 all leading * and trailing space removed, where space is defined * as any character whose codepoint is less than or equal to * {@code 'U+0020'} (the space character). * <p> * 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 * that are not space (as defined above), then a * reference to this {@code String} object is returned. * <p> * Otherwise, if all characters in this string are space (as * defined above), then a {@code String} object representing an * empty string is returned. * <p> * Otherwise, let <i>k</i> be the index of the first character in the * string whose code is not a space (as defined above) and let * <i>m</i> be the index of the last character in the string whose code * is not a space (as defined above). A {@code String} * object is returned, representing the substring of this string that * begins with the character at index <i>k</i> and ends with the * character at index <i>m</i>-that is, the result of * {@code this.substring(k, m + 1)}. * <p> * This method may be used to trim space (as defined above) from * the beginning and end of a string. * * @return a string whose value is this string, with all leading * and trailing space removed, or this string if it * has no leading or trailing space. */ public String trim() { String ret = isLatin1() ? StringLatin1.trim(value) : StringUTF16.trim(value); return ret == null ? this : ret; } /** * Returns a string whose value is this string, with all leading * and trailing {@linkplain Character#isWhitespace(int) white space} * removed. * <p> * If this {@code String} object represents an empty string, * or if all code points in this string are * {@linkplain Character#isWhitespace(int) white space}, then an empty string * is returned. * <p> * Otherwise, returns a substring of this string beginning with the first * code point that is not a {@linkplain Character#isWhitespace(int) white space} * up to and including the last code point that is not a * {@linkplain Character#isWhitespace(int) white space}. * <p> * This method may be used to strip * {@linkplain Character#isWhitespace(int) white space} from * the beginning and end of a string. * * @return a string whose value is this string, with all leading * and trailing white space removed * * @see Character#isWhitespace(int) * * @since 11 */ public String strip() { String ret = isLatin1() ? StringLatin1.strip(value) : StringUTF16.strip(value); return ret == null ? this : ret; } /** * Returns a string whose value is this string, with all leading * {@linkplain Character#isWhitespace(int) white space} removed. * <p> * If this {@code String} object represents an empty string, * or if all code points in this string are * {@linkplain Character#isWhitespace(int) white space}, then an empty string * is returned. * <p> * Otherwise, returns a substring of this string beginning with the first * code point that is not a {@linkplain Character#isWhitespace(int) white space} * up to and including the last code point of this string. * <p> * This method may be used to trim * {@linkplain Character#isWhitespace(int) white space} from * the beginning of a string. * * @return a string whose value is this string, with all leading white * space removed * * @see Character#isWhitespace(int) * * @since 11 */ public String stripLeading() { String ret = isLatin1() ? StringLatin1.stripLeading(value) : StringUTF16.stripLeading(value); return ret == null ? this : ret; } /** * Returns a string whose value is this string, with all trailing * {@linkplain Character#isWhitespace(int) white space} removed. * <p> * If this {@code String} object represents an empty string, * or if all characters in this string are * {@linkplain Character#isWhitespace(int) white space}, then an empty string * is returned. * <p> * Otherwise, returns a substring of this string beginning with the first * code point of this string up to and including the last code point * that is not a {@linkplain Character#isWhitespace(int) white space}. * <p> * This method may be used to trim * {@linkplain Character#isWhitespace(int) white space} from * the end of a string. * * @return a string whose value is this string, with all trailing white * space removed * * @see Character#isWhitespace(int) * * @since 11 */ public String stripTrailing() { String ret = isLatin1() ? StringLatin1.stripTrailing(value) : StringUTF16.stripTrailing(value); return ret == null ? this : ret; } /** * Returns {@code true} if the string is empty or contains only * {@linkplain Character#isWhitespace(int) white space} codepoints, * otherwise {@code false}. * * @return {@code true} if the string is empty or contains only * {@linkplain Character#isWhitespace(int) white space} codepoints, * otherwise {@code false} * * @see Character#isWhitespace(int) * * @since 11 */ public boolean isBlank() { return indexOfNonWhitespace() == length(); } /** * Returns a stream of lines extracted from this string, * separated by line terminators. * <p> * A <i>line terminator</i> is one of the following: * a line feed character {@code "\n"} (U+000A), * a carriage return character {@code "\r"} (U+000D), * or a carriage return followed immediately by a line feed * {@code "\r\n"} (U+000D U+000A). * <p> * A <i>line</i> is either a sequence of zero or more characters * followed by a line terminator, or it is a sequence of one or * more characters followed by the end of the string. A * line does not include the line terminator. * <p> * The stream returned by this method contains the lines from * this string in the order in which they occur. * * @apiNote This definition of <i>line</i> implies that an empty * string has zero lines and that there is no empty line * following a line terminator at the end of a string. * * @implNote This method provides better performance than * split("\R") by supplying elements lazily and * by faster search of new line terminators. * * @return the stream of lines extracted from this string * * @since 11 */ public Stream<String> lines() { return isLatin1() ? StringLatin1.lines(value) : StringUTF16.lines(value); } /** * Adjusts the indentation of each line of this string based on the value of * {@code n}, and normalizes line termination characters. * <p> * This string is conceptually separated into lines using * {@link String#lines()}. Each line is then adjusted as described below * and then suffixed with a line feed {@code "\n"} (U+000A). The resulting * lines are then concatenated and returned. * <p> * If {@code n > 0} then {@code n} spaces (U+0020) are inserted at the * beginning of each line. * <p> * If {@code n < 0} then up to {@code n} * {@linkplain Character#isWhitespace(int) white space characters} are removed * from the beginning of each line. If a given line does not contain * sufficient white space then all leading * {@linkplain Character#isWhitespace(int) white space characters} are removed. * Each white space character is treated as a single character. In * particular, the tab character {@code "\t"} (U+0009) is considered a * single character; it is not expanded. * <p> * If {@code n == 0} then the line remains unchanged. However, line * terminators are still normalized. * * @param n number of leading * {@linkplain Character#isWhitespace(int) white space characters} * to add or remove * * @return string with indentation adjusted and line endings normalized * * @see String#lines() * @see String#isBlank() * @see Character#isWhitespace(int) * * @since 12 */ public String indent(int n) { if (isEmpty()) { return ""; } Stream<String> stream = lines(); if (n > 0) { final String spaces = " ".repeat(n); stream = stream.map(s -> spaces + s); } else if (n == Integer.MIN_VALUE) { stream = stream.map(s -> s.stripLeading()); } else if (n < 0) { stream = stream.map(s -> s.substring(Math.min(-n, s.indexOfNonWhitespace()))); } return stream.collect(Collectors.joining("\n", "", "\n")); } private int indexOfNonWhitespace() { return isLatin1() ? StringLatin1.indexOfNonWhitespace(value) : StringUTF16.indexOfNonWhitespace(value); } private int lastIndexOfNonWhitespace() { return isLatin1() ? StringLatin1.lastIndexOfNonWhitespace(value) : StringUTF16.lastIndexOfNonWhitespace(value); } /** * Returns a string whose value is this string, with incidental * {@linkplain Character#isWhitespace(int) white space} removed from * the beginning and end of every line. * <p> * Incidental {@linkplain Character#isWhitespace(int) white space} * is often present in a text block to align the content with the opening * delimiter. For example, in the following code, dots represent incidental * {@linkplain Character#isWhitespace(int) white space}: * <blockquote><pre> * String html = """ * ..............<html> * .............. <body> * .............. <p>Hello, world</p> * .............. </body> * ..............</html> * .............."""; * </pre></blockquote> * This method treats the incidental * {@linkplain Character#isWhitespace(int) white space} as indentation to be * stripped, producing a string that preserves the relative indentation of * the content. Using | to visualize the start of each line of the string: * <blockquote><pre> * |<html> * | <body> * | <p>Hello, world</p> * | </body> * |</html> * </pre></blockquote> * First, the individual lines of this string are extracted as if by using * {@link String#lines()}. * <p> * Then, the <i>minimum indentation</i> (min) is determined as follows. * For each non-blank line (as defined by {@link String#isBlank()}), the * leading {@linkplain Character#isWhitespace(int) white space} characters are * counted. The leading {@linkplain Character#isWhitespace(int) white space} * characters on the last line are also counted even if * {@linkplain String#isBlank() blank}. The <i>min</i> value is the smallest * of these counts. * <p> * For each {@linkplain String#isBlank() non-blank} line, <i>min</i> leading * {@linkplain Character#isWhitespace(int) white space} characters are removed, * and any trailing {@linkplain Character#isWhitespace(int) white space} * characters are removed. {@linkplain String#isBlank() Blank} lines are * replaced with the empty string. * * <p> * Finally, the lines are joined into a new string, using the LF character * {@code "\n"} (U+000A) to separate lines. * * @apiNote * This method's primary purpose is to shift a block of lines as far as * possible to the left, while preserving relative indentation. Lines * that were indented the least will thus have no leading * {@linkplain Character#isWhitespace(int) white space}. * The line count of the result will be the same as line count of this * string. * If this string ends with a line terminator then the result will end * with a line terminator. * * @implNote * This method treats all {@linkplain Character#isWhitespace(int) white space} * characters as having equal width. As long as the indentation on every * line is consistently composed of the same character sequences, then the * result will be as described above. * * @return string with incidental indentation removed and line * terminators normalized * * @see String#lines() * @see String#isBlank() * @see String#indent(int) * @see Character#isWhitespace(int) * * @since 13 * * @deprecated This method is associated with text blocks, a preview language feature. * Text blocks and/or this method may be changed or removed in a future release. */ @Deprecated(forRemoval = true, since = "13") public String stripIndent() { int length = length(); if (length == 0) { return ""; } char lastChar = charAt(length - 1); boolean optOut = lastChar == '\n' || lastChar == '\r'; List<String> lines = lines().collect(Collectors.toList()); final int outdent = optOut ? 0 : outdent(lines); return lines.stream().map(line -> { int firstNonWhitespace = line.indexOfNonWhitespace(); int lastNonWhitespace = line.lastIndexOfNonWhitespace(); int incidentalWhitespace = Math.min(outdent, firstNonWhitespace); return firstNonWhitespace > lastNonWhitespace ? "" : line.substring(incidentalWhitespace, lastNonWhitespace); }).collect(Collectors.joining("\n", "", optOut ? "\n" : "")); } private static int outdent(List<String> lines) { // Note: outdent is guaranteed to be zero or positive number. // If there isn't a non-blank line then the last must be blank int outdent = Integer.MAX_VALUE; for (String line : lines) { int leadingWhitespace = line.indexOfNonWhitespace(); if (leadingWhitespace != line.length()) { outdent = Integer.min(outdent, leadingWhitespace); } } String lastLine = lines.get(lines.size() - 1); if (lastLine.isBlank()) { outdent = Integer.min(outdent, lastLine.length()); } return outdent; } /** * Returns a string whose value is this string, with escape sequences * translated as if in a string literal. * <p> * Escape sequences are translated as follows; * <table class="striped"> * <caption style="display:none">Translation</caption> * <thead> * <tr> * <th scope="col">Escape</th> * <th scope="col">Name</th> * <th scope="col">Translation</th> * </tr> * </thead> * <tbody> * <tr> * <th scope="row">{@code \u005Cb}</th> * <td>backspace</td> * <td>{@code U+0008}</td> * </tr> * <tr> * <th scope="row">{@code \u005Ct}</th> * <td>horizontal tab</td> * <td>{@code U+0009}</td> * </tr> * <tr> * <th scope="row">{@code \u005Cn}</th> * <td>line feed</td> * <td>{@code U+000A}</td> * </tr> * <tr> * <th scope="row">{@code \u005Cf}</th> * <td>form feed</td> * <td>{@code U+000C}</td> * </tr> * <tr> * <th scope="row">{@code \u005Cr}</th> * <td>carriage return</td> * <td>{@code U+000D}</td> * </tr> * <tr> * <th scope="row">{@code \u005C"}</th> * <td>double quote</td> * <td>{@code U+0022}</td> * </tr> * <tr> * <th scope="row">{@code \u005C'}</th> * <td>single quote</td> * <td>{@code U+0027}</td> * </tr> * <tr> * <th scope="row">{@code \u005C\u005C}</th> * <td>backslash</td> * <td>{@code U+005C}</td> * </tr> * <tr> * <th scope="row">{@code \u005C0 - \u005C377}</th> * <td>octal escape</td> * <td>code point equivalents</td> * </tr> * </tbody> * </table> * * @implNote * This method does <em>not</em> translate Unicode escapes such as "{@code \u005cu2022}". * Unicode escapes are translated by the Java compiler when reading input characters and * are not part of the string literal specification. * * @throws IllegalArgumentException when an escape sequence is malformed. * * @return String with escape sequences translated. * * @jls 3.10.7 Escape Sequences * * @since 13 * * @deprecated This method is associated with text blocks, a preview language feature. * Text blocks and/or this method may be changed or removed in a future release. */ @Deprecated(forRemoval = true, since = "13") public String translateEscapes() { if (isEmpty()) { return ""; } char[] chars = toCharArray(); int length = chars.length; int from = 0; int to = 0; while (from < length) { char ch = chars[from++]; if (ch == '\\') { ch = from < length ? chars[from++] : '\0'; switch (ch) { case 'b': ch = '\b'; break; case 'f': ch = '\f'; break; case 'n': ch = '\n'; break; case 'r': ch = '\r'; break; case 't': ch = '\t'; break; case '\'': case '\"': case '\\': // as is break; case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': int limit = Integer.min(from + (ch <= '3' ? 2 : 1), length); int code = ch - '0'; while (from < limit) { ch = chars[from]; if (ch < '0' || '7' < ch) { break; } from++; code = (code << 3) | (ch - '0'); } ch = (char) code; break; default: { String msg = String.format("Invalid escape sequence: \\%c \\\\u%04X", ch, (int) ch); throw new IllegalArgumentException(msg); } } } chars[to++] = ch; } return new String(chars, 0, to); } /** * This method allows the application of a function to {@code this} * string. The function should expect a single String argument * and produce an {@code R} result. * <p> * Any exception thrown by {@code f()} will be propagated to the * caller. * * @param f functional interface to a apply * * @param <R> class of the result * * @return the result of applying the function to this string * * @see java.util.function.Function * * @since 12 */ public <R> R transform(Function<? super String, ? extends R> f) { return f.apply(this); } /** * This object (which is already a string!) is itself returned. * * @return the string itself. */ public String toString() { return this; } /** * Returns a stream of {@code int} zero-extending the {@code char} values * from this sequence. Any char which maps to a <a * href="{@docRoot}/java.base/java/lang/Character.html#unicode">surrogate code * point</a> is passed through uninterpreted. * * @return an IntStream of char values from this sequence * @since 9 */ @Override public IntStream chars() { return StreamSupport.intStream(isLatin1() ? new StringLatin1.CharsSpliterator(value, Spliterator.IMMUTABLE) : new StringUTF16.CharsSpliterator(value, Spliterator.IMMUTABLE), false); } /** * Returns a stream of code point values from this sequence. Any surrogate * pairs encountered in the sequence are combined as if by {@linkplain * Character#toCodePoint Character.toCodePoint} and the result is passed * to the stream. Any other code units, including ordinary BMP characters, * unpaired surrogates, and undefined code units, are zero-extended to * {@code int} values which are then passed to the stream. * * @return an IntStream of Unicode code points from this sequence * @since 9 */ @Override public IntStream codePoints() { return StreamSupport.intStream(isLatin1() ? new StringLatin1.CharsSpliterator(value, Spliterator.IMMUTABLE) : new StringUTF16.CodePointsSpliterator(value, Spliterator.IMMUTABLE), false); } /** * 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() { return isLatin1() ? StringLatin1.toChars(value) : StringUTF16.toChars(value); } /** * Returns a formatted string using the specified format string and * arguments. * * <p> The locale always used is the one returned by {@link * java.util.Locale#getDefault(java.util.Locale.Category) * Locale.getDefault(Locale.Category)} with * {@link java.util.Locale.Category#FORMAT FORMAT} category specified. * * @param format * A <a href="../util/Formatter.html#syntax">format string</a> * * @param args * Arguments referenced by the format specifiers in the format * string. If there are more arguments than format specifiers, the * extra arguments are ignored. The number of arguments is * variable and may be zero. The maximum number of arguments is * limited by the maximum dimension of a Java array as defined by * <cite>The Java™ Virtual Machine Specification</cite>. * The behaviour on a * {@code null} argument depends on the <a * href="../util/Formatter.html#syntax">conversion</a>. * * @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 <a * href="../util/Formatter.html#detail">Details</a> 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 <a href="../util/Formatter.html#syntax">format string</a> * * @param args * Arguments referenced by the format specifiers in the format * string. If there are more arguments than format specifiers, the * extra arguments are ignored. The number of arguments is * variable and may be zero. The maximum number of arguments is * limited by the maximum dimension of a Java array as defined by * <cite>The Java™ Virtual Machine Specification</cite>. * The behaviour on a * {@code null} argument depends on the * <a href="../util/Formatter.html#syntax">conversion</a>. * * @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 <a * href="../util/Formatter.html#detail">Details</a> 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(); } /** * Formats using this string as the format string, and the supplied * arguments. * * @implSpec This method is equivalent to {@code String.format(this, args)}. * * @param args * Arguments referenced by the format specifiers in this string. * * @return A formatted string * * @see java.lang.String#format(String,Object...) * @see java.util.Formatter * * @since 13 * * @deprecated This method is associated with text blocks, a preview language feature. * Text blocks and/or this method may be changed or removed in a future release. */ @Deprecated(forRemoval = true, since = "13") public String formatted(Object... args) { return new Formatter().format(this, 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. * <p> * 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) { if (COMPACT_STRINGS && StringLatin1.canEncode(c)) { return new String(StringLatin1.toBytes(c), LATIN1); } return new String(StringUTF16.toBytes(c), UTF16); } /** * Returns the string representation of the {@code int} argument. * <p> * 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. * <p> * 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. * <p> * 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. * <p> * 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. * <p> * A pool of strings, initially empty, is maintained privately by the * class {@code String}. * <p> * 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. * <p> * 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}. * <p> * All literal strings and string-valued constant expressions are * interned. String literals are defined in section 3.10.5 of the * <cite>The Java™ Language Specification</cite>. * * @return a string that has the same contents as this string, but is * guaranteed to be from a pool of unique strings. * @jls 3.10.5 String Literals */ public native String intern(); /** * Returns a string whose value is the concatenation of this * string repeated {@code count} times. * <p> * If this string is empty or count is zero then the empty * string is returned. * * @param count number of times to repeat * * @return A string composed of this string repeated * {@code count} times or the empty string if this * string is empty or count is zero * * @throws IllegalArgumentException if the {@code count} is * negative. * * @since 11 */ public String repeat(int count) { if (count < 0) { throw new IllegalArgumentException("count is negative: " + count); } if (count == 1) { return this; } final int len = value.length; if (len == 0 || count == 0) { return ""; } if (len == 1) { final byte[] single = new byte[count]; Arrays.fill(single, value[0]); return new String(single, coder); } if (Integer.MAX_VALUE / count < len) { throw new OutOfMemoryError("Repeating " + len + " bytes String " + count + " times will produce a String exceeding maximum size."); } final int limit = len * count; final byte[] multiple = new byte[limit]; System.arraycopy(value, 0, multiple, 0, len); int copied = len; for (; copied < limit - copied; copied <<= 1) { System.arraycopy(multiple, 0, multiple, copied, copied); } System.arraycopy(multiple, 0, multiple, copied, limit - copied); return new String(multiple, coder); } //////////////////////////////////////////////////////////////// /** * Copy character bytes from this string into dst starting at dstBegin. * This method doesn't perform any range checking. * * Invoker guarantees: dst is in UTF16 (inflate itself for asb), if two * coders are different, and dst is big enough (range check) * * @param dstBegin the char index, not offset of byte[] * @param coder the coder of dst[] */ void getBytes(byte dst[], int dstBegin, byte coder) { if (coder() == coder) { System.arraycopy(value, 0, dst, dstBegin << coder, value.length); } else { // this.coder == LATIN && coder == UTF16 StringLatin1.inflate(value, 0, dst, dstBegin, value.length); } } /* * Package private constructor. Trailing Void argument is there for * disambiguating it against other (public) constructors. * * Stores the char[] value into a byte[] that each byte represents * the8 low-order bits of the corresponding character, if the char[] * contains only latin1 character. Or a byte[] that stores all * characters in their byte sequences defined by the {@code StringUTF16}. */ String(char[] value, int off, int len, Void sig) { if (len == 0) { this.value = "".value; this.coder = "".coder; return; } if (COMPACT_STRINGS) { byte[] val = StringUTF16.compress(value, off, len); if (val != null) { this.value = val; this.coder = LATIN1; return; } } this.coder = UTF16; this.value = StringUTF16.toBytes(value, off, len); } /* * Package private constructor. Trailing Void argument is there for * disambiguating it against other (public) constructors. */ String(AbstractStringBuilder asb, Void sig) { byte[] val = asb.getValue(); int length = asb.length(); if (asb.isLatin1()) { this.coder = LATIN1; this.value = Arrays.copyOfRange(val, 0, length); } else { if (COMPACT_STRINGS) { byte[] buf = StringUTF16.compress(val, 0, length); if (buf != null) { this.coder = LATIN1; this.value = buf; return; } } this.coder = UTF16; this.value = Arrays.copyOfRange(val, 0, length << 1); } } /* * Package private constructor which shares value array for speed. */ String(byte[] value, byte coder) { this.value = value; this.coder = coder; } byte coder() { return COMPACT_STRINGS ? coder : UTF16; } byte[] value() { return value; } boolean isLatin1() { return COMPACT_STRINGS && coder == LATIN1; } @Native static final byte LATIN1 = 0; @Native static final byte UTF16 = 1; /* * StringIndexOutOfBoundsException if {@code index} is * negative or greater than or equal to {@code length}. */ static void checkIndex(int index, int length) { if (index < 0 || index >= length) { throw new StringIndexOutOfBoundsException("index " + index + ",length " + length); } } /* * StringIndexOutOfBoundsException if {@code offset} * is negative or greater than {@code length}. */ static void checkOffset(int offset, int length) { if (offset < 0 || offset > length) { throw new StringIndexOutOfBoundsException("offset " + offset + ",length " + length); } } /* * Check {@code offset}, {@code count} against {@code 0} and {@code length} * bounds. * * @throws StringIndexOutOfBoundsException * If {@code offset} is negative, {@code count} is negative, * or {@code offset} is greater than {@code length - count} */ static void checkBoundsOffCount(int offset, int count, int length) { if (offset < 0 || count < 0 || offset > length - count) { throw new StringIndexOutOfBoundsException( "offset " + offset + ", count " + count + ", length " + length); } } /* * Check {@code begin}, {@code end} against {@code 0} and {@code length} * bounds. * * @throws StringIndexOutOfBoundsException * If {@code begin} is negative, {@code begin} is greater than * {@code end}, or {@code end} is greater than {@code length}. */ static void checkBoundsBeginEnd(int begin, int end, int length) { if (begin < 0 || begin > end || end > length) { throw new StringIndexOutOfBoundsException("begin " + begin + ", end " + end + ", length " + length); } } /** * Returns the string representation of the {@code codePoint} * argument. * * @param codePoint a {@code codePoint}. * @return a string of length {@code 1} or {@code 2} containing * as its single character the argument {@code codePoint}. * @throws IllegalArgumentException if the specified * {@code codePoint} is not a {@linkplain Character#isValidCodePoint * valid Unicode code point}. */ static String valueOfCodePoint(int codePoint) { if (COMPACT_STRINGS && StringLatin1.canEncode(codePoint)) { return new String(StringLatin1.toBytes((char) codePoint), LATIN1); } else if (Character.isBmpCodePoint(codePoint)) { return new String(StringUTF16.toBytes((char) codePoint), UTF16); } else if (Character.isSupplementaryCodePoint(codePoint)) { return new String(StringUTF16.toBytesSupplementary(codePoint), UTF16); } throw new IllegalArgumentException(format("Not a valid Unicode code point: 0x%X", codePoint)); } /** * Returns an {@link Optional} containing the nominal descriptor for this * instance, which is the instance itself. * * @return an {@link Optional} describing the {@linkplain String} instance * @since 12 */ @Override public Optional<String> describeConstable() { return Optional.of(this); } /** * Resolves this instance as a {@link ConstantDesc}, the result of which is * the instance itself. * * @param lookup ignored * @return the {@linkplain String} instance * @since 12 */ @Override public String resolveConstantDesc(MethodHandles.Lookup lookup) { return this; } }