/*
* @(#)String.java 1.145 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.lang;
import sun.misc.CVM;
import java.io.ObjectStreamClass;
import java.io.ObjectStreamField;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Locale;
/**
* The <code>String</code> class represents character strings. All
* string literals in Java programs, such as <code>"abc"</code>, are
* implemented as instances of this class.
* <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:
* <p><blockquote><pre>
* String str = "abc";
* </pre></blockquote><p>
* is equivalent to:
* <p><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:
* <p><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</code> includes methods for examining
* individual characters of the sequence, for comparing strings, for
* searching strings, for extracting substrings, and for creating a
* copy of a string with all characters translated to uppercase or to
* lowercase. Case mapping relies heavily on the information provided
* by the Unicode Consortium's Unicode 3.0 specification. The
* specification's UnicodeData.txt and SpecialCasing.txt files are
* used extensively to provide case mapping.
* <p>
* The Java language provides special support for the string
* concatenation operator ( + ), and for conversion of
* other objects to strings. String concatenation is implemented
* through the <code>StringBuffer</code> class and its
* <code>append</code> method.
* String conversions are implemented through the method
* <code>toString</code>, defined by <code>Object</code> and
* inherited by all classes in Java. For additional information on
* string concatenation and conversion, see Gosling, Joy, and Steele,
* <i>The Java Language Specification</i>.
*
* <p> Unless otherwise noted, passing a <tt>null</tt> argument to a constructor
* or method in this class will cause a {@link NullPointerException} to be
* thrown.
*
* @author Lee Boynton
* @author Arthur van Hoff
* @version 1.152, 02/01/03
* @see java.lang.Object#toString()
* @see java.lang.StringBuffer
* @see java.lang.StringBuffer#append(boolean)
* @see java.lang.StringBuffer#append(char)
* @see java.lang.StringBuffer#append(char[])
* @see java.lang.StringBuffer#append(char[], int, int)
* @see java.lang.StringBuffer#append(double)
* @see java.lang.StringBuffer#append(float)
* @see java.lang.StringBuffer#append(int)
* @see java.lang.StringBuffer#append(long)
* @see java.lang.StringBuffer#append(java.lang.Object)
* @see java.lang.StringBuffer#append(java.lang.String)
* @since JDK1.0
*/
public final class String
implements java.io.Serializable, Comparable, CharSequence
{
/** The value is used for character storage. */
private char value[];
/** The offset is the first index of the storage that is used. */
private int offset;
/** The count is the number of characters in the String. */
private int count;
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = -6849794470754667710L;
/**
* Class String is special cased within the Serialization Stream Protocol.
*
* A String instance is written intially into an ObjectOutputStream in the
* following format:
* <pre>
* <code>TC_STRING</code> (utf String)
* </pre>
* The String is written by method <code>DataOutput.writeUTF</code>.
* A new handle is generated to refer to all future references to the
* string instance within the stream.
*/
private static final ObjectStreamField[] serialPersistentFields =
new ObjectStreamField[0];
/**
* Initializes a newly created <code>String</code> object so that it
* represents an empty character sequence. Note that use of this
* constructor is unnecessary since Strings are immutable.
*/
public String() {
value = new char[0];
}
/**
* Initializes a newly created <code>String</code> 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</code> is needed, use of this
* constructor is unnecessary since Strings are immutable.
*
* @param original a <code>String</code>.
*/
public String(String original) {
this.count = original.count;
if (original.value.length > this.count) {
// The array representing the String is bigger than the new
// String itself. Perhaps this constructor is being called
// in order to trim the baggage, so make a copy of the array.
this.value = new char[this.count];
CVM.copyCharArray(original.value, original.offset,
this.value, 0, this.count);
} else {
// The array representing the String is the same
// size as the String, so no point in making a copy.
this.value = original.value;
}
}
/**
* Allocates a new <code>String</code> 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.count = value.length;
this.value = new char[count];
CVM.copyCharArray(value, 0, this.value, 0, count);
}
/**
* Allocates a new <code>String</code> that contains characters from
* a subarray of the character array argument. The <code>offset</code>
* argument is the index of the first character of the subarray and
* the <code>count</code> argument specifies the length of the
* subarray. The contents of the subarray are copied; subsequent
* modification of the character array does not affect the newly
* created string.
*
* @param value array that is the source of characters.
* @param offset the initial offset.
* @param count the length.
* @exception IndexOutOfBoundsException if the <code>offset</code>
* and <code>count</code> arguments index characters outside
* the bounds of the <code>value</code> array.
*/
public String(char value[], int offset, int count) {
if (offset < 0) {
throw new StringIndexOutOfBoundsException(offset);
}
if (count < 0) {
throw new StringIndexOutOfBoundsException(count);
}
// Note: offset or count might be near -1>>>1.
if (offset > value.length - count) {
throw new StringIndexOutOfBoundsException(offset + count);
}
this.value = new char[count];
this.count = count;
CVM.copyCharArray(value, offset, this.value, 0, count);
}
/**
* Allocates a new <code>String</code> constructed from a subarray
* of an array of 8-bit integer values.
* <p>
* The <code>offset</code> argument is the index of the first byte
* of the subarray, and the <code>count</code> argument specifies the
* length of the subarray.
* <p>
* Each <code>byte</code> in the subarray is converted to a
* <code>char</code> as specified in the method above.
*
* deprecated This method does not properly convert bytes into characters.
* As of JDK 1.1, the preferred way to do this is via the
* <code>String</code> constructors that take a 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 character.
* param offset the initial offset.
* param count the length.
* exception IndexOutOfBoundsException if the <code>offset</code>
* or <code>count</code> argument is invalid.
* @see java.lang.String#String(byte[], int)
* @see java.lang.String#String(byte[], int, int, java.lang.String)
* @see java.lang.String#String(byte[], int, int)
* @see java.lang.String#String(byte[], java.lang.String)
* @see java.lang.String#String(byte[])
*/
/*
public String(byte ascii[], int hibyte, int offset, int count) {
//checkBounds(ascii, offset, count);
char value[] = new char[count];
this.count = count;
this.value = value;
if (hibyte == 0) {
for (int i = count ; i-- > 0 ;) {
value[i] = (char) (ascii[i + offset] & 0xff);
}
} else {
hibyte <<= 8;
for (int i = count ; i-- > 0 ;) {
value[i] = (char) (hibyte | (ascii[i + offset] & 0xff));
}
}
}
*/
/**
* Allocates a new <code>String</code> 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:
* <p><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</code> constructors that take a 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 character.
* @see java.lang.String#String(byte[], int, int, java.lang.String)
* @see java.lang.String#String(byte[], int, int)
* @see java.lang.String#String(byte[], java.lang.String)
* @see java.lang.String#String(byte[])
*/
/*
public String(byte ascii[], int hibyte) {
this(ascii, hibyte, 0, ascii.length);
}
*/
/* Common private utility method used to bounds check the byte array
* and requested offset & length values used by the String(byte[],..)
* constructors.
*/
private static void checkBounds(byte[] bytes, int offset, int length) {
if (length < 0)
throw new StringIndexOutOfBoundsException(length);
if (offset < 0)
throw new StringIndexOutOfBoundsException(offset);
if (offset > bytes.length - length)
throw new StringIndexOutOfBoundsException(offset + length);
}
/**
* Constructs a new <tt>String</tt> by decoding the specified subarray of
* bytes using the specified charset. The length of the new
* <tt>String</tt> 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.
*
* @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 encoding
*
* @throws UnsupportedEncodingException
* if the named charset is not supported
* @throws IndexOutOfBoundsException
* if the <tt>offset</tt> and <tt>length</tt> arguments
* index characters outside the bounds of the <tt>bytes</tt>
* array
* @since JDK1.1
*/
public String(byte bytes[], int offset, int length, String charsetName)
throws UnsupportedEncodingException
{
if (charsetName == null)
throw new NullPointerException("charsetName");
checkBounds(bytes, offset, length);
value = StringCoding.decode(charsetName, bytes, offset, length);
count = value.length;
}
/**
* Constructs a new <tt>String</tt> by decoding the specified array of
* bytes using the specified charset. The length of the new
* <tt>String</tt> 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.
*
* @param bytes the bytes to be decoded into characters
* @param charsetName the name of a supported encoding
*
* @exception UnsupportedEncodingException
* If the named charset is not supported
* @since JDK1.1
*/
public String(byte bytes[], String charsetName)
throws UnsupportedEncodingException
{
this(bytes, 0, bytes.length, charsetName);
}
/**
* Constructs a new <tt>String</tt> by decoding the specified subarray of
* bytes using the platform's default charset. The length of the new
* <tt>String</tt> 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.
*
* @param bytes the bytes to be decoded into characters
* @param offset the index of the first byte to decode
* @param length the number of bytes to decode
* @throws IndexOutOfBoundsException
* if the <code>offset</code> and the <code>length</code>
* arguments index characters outside the bounds of the
* <code>bytes</code> array
* @since JDK1.1
*/
public String(byte bytes[], int offset, int length) {
checkBounds(bytes, offset, length);
value = StringCoding.decode(bytes, offset, length);
count = value.length;
}
/**
* Constructs a new <tt>String</tt> by decoding the specified array of
* bytes using the platform's default charset. The length of the new
* <tt>String</tt> 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.
*
* @param bytes the bytes to be decoded into characters
* @since JDK1.1
*/
public String(byte bytes[]) {
this(bytes, 0, bytes.length);
}
/**
* Allocates a new string that contains the sequence of characters
* currently contained in the string buffer argument. The contents of
* the string buffer are copied; subsequent modification of the string
* buffer does not affect the newly created string.
*
* @param buffer a <code>StringBuffer</code>.
*/
public String (StringBuffer buffer) {
synchronized(buffer) {
buffer.setShared();
this.value = buffer.getValue();
this.offset = 0;
this.count = buffer.lengthNoSync();
}
}
private void initSimpleSync(StringBuffer buffer) {
if (buffer != null && CVM.simpleLockGrab(buffer)) {
/* Note, method calls are made below, which is usualy a no no
* after calling simpleLockGrab(). However, this method is marked
* as CVMJIT_NEEDS_TO_INLINE, which will only allow this method
* to be compiled if the simple method calls below can also
* be inlined.
*/
buffer.setShared();
this.value = buffer.getValue();
this.offset = 0;
this.count = buffer.lengthNoSync();
CVM.simpleLockRelease(buffer);
return;
}
initSync(buffer);
}
private void initSync(StringBuffer buffer) {
synchronized(buffer) {
buffer.setShared();
this.value = buffer.getValue();
this.offset = 0;
this.count = buffer.lengthNoSync();
}
}
// Package private constructor which shares value array for speed.
String(int offset, int count, char value[]) {
this.value = value;
this.offset = offset;
this.count = count;
}
/**
* Returns the length of this string.
* The length is equal to the number of 16-bit
* Unicode characters in the string.
*
* @return the length of the sequence of characters represented by this
* object.
*/
public int length() {
return count;
}
/**
* Returns the character at the specified index. An index ranges
* from <code>0</code> to <code>length() - 1</code>. The first character
* of the sequence is at index <code>0</code>, the next at index
* <code>1</code>, and so on, as for array indexing.
*
* @param index the index of the character.
* @return the character at the specified index of this string.
* The first character is at index <code>0</code>.
* @exception IndexOutOfBoundsException if the <code>index</code>
* argument is negative or not less than the length of this
* string.
*/
public char charAt(int index) {
if ((index < 0) || (index >= count)) {
throw new StringIndexOutOfBoundsException(index);
}
return value[index + offset];
}
/**
* Copies characters from this string into the destination character
* array.
* <p>
* The first character to be copied is at index <code>srcBegin</code>;
* the last character to be copied is at index <code>srcEnd-1</code>
* (thus the total number of characters to be copied is
* <code>srcEnd-srcBegin</code>). The characters are copied into the
* subarray of <code>dst</code> starting at index <code>dstBegin</code>
* and ending at index:
* <p><blockquote><pre>
* dstbegin + (srcEnd-srcBegin) - 1
* </pre></blockquote>
*
* @param srcBegin index of the first character in the string
* to copy.
* @param srcEnd index after the last character in the string
* to copy.
* @param dst the destination array.
* @param dstBegin the start offset in the destination array.
* @exception IndexOutOfBoundsException If any of the following
* is true:
* <ul><li><code>srcBegin</code> is negative.
* <li><code>srcBegin</code> is greater than <code>srcEnd</code>
* <li><code>srcEnd</code> is greater than the length of this
* string
* <li><code>dstBegin</code> is negative
* <li><code>dstBegin+(srcEnd-srcBegin)</code> is larger than
* <code>dst.length</code></ul>
*/
public native void getChars(int srcBegin, int srcEnd,
char dst[], int dstBegin);
/*
* The original Java version.
*
* public void getChars(int srcBegin, int srcEnd, char dst[], int dstBegin) {
* if (srcBegin < 0) {
* throw new StringIndexOutOfBoundsException(srcBegin);
* }
* if (srcEnd > count) {
* throw new StringIndexOutOfBoundsException(srcEnd);
* }
* if (srcBegin > srcEnd) {
* throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
* }
* System.arraycopy(value, offset + srcBegin, dst, dstBegin,
* srcEnd - srcBegin);
* }
*/
/**
* Copies characters from this string into the destination byte
* array. Each byte receives the 8 low-order bits of the
* corresponding character. The eight high-order bits of each character
* are not copied and do not participate in the transfer in any way.
* <p>
* The first character to be copied is at index <code>srcBegin</code>;
* the last character to be copied is at index <code>srcEnd-1</code>.
* The total number of characters to be copied is
* <code>srcEnd-srcBegin</code>. The characters, converted to bytes,
* are copied into the subarray of <code>dst</code> starting at index
* <code>dstBegin</code> and ending at index:
* <p><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
* the <code>getBytes()</code> 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.
* @exception IndexOutOfBoundsException if any of the following
* is true:
* <ul><li><code>srcBegin</code> is negative
* <li><code>srcBegin</code> is greater than <code>srcEnd</code>
* <li><code>srcEnd</code> is greater than the length of this
* String
* <li><code>dstBegin</code> is negative
* <li><code>dstBegin+(srcEnd-srcBegin)</code> is larger than
* <code>dst.length</code></ul>
*
public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
if (srcBegin < 0) {
throw new StringIndexOutOfBoundsException(srcBegin);
}
if (srcEnd > count) {
throw new StringIndexOutOfBoundsException(srcEnd);
}
if (srcBegin > srcEnd) {
throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
}
int j = dstBegin;
int n = offset + srcEnd;
int i = offset + srcBegin;
char[] val = value; /* avoid getfield opcode *
while (i < n) {
dst[j++] = (byte)val[i++];
}
}
*/
/**
* Encodes this <tt>String</tt> 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.
*
* @param charsetName
* the name of a supported encoding
*
* @return The resultant byte array
*
* @exception UnsupportedEncodingException
* If the named charset is not supported
*
* @since JDK1.1
*/
public byte[] getBytes(String charsetName)
throws UnsupportedEncodingException
{
return StringCoding.encode(charsetName, value, offset, count);
}
/**
* Encodes this <tt>String</tt> 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.
*
* @return The resultant byte array
*
* @since JDK1.1
*/
public byte[] getBytes() {
return StringCoding.encode(value, offset, count);
}
/**
* Compares this string to the specified object.
* The result is <code>true</code> if and only if the argument is not
* <code>null</code> and is a <code>String</code> object that represents
* the same sequence of characters as this object.
*
* @param anObject the object to compare this <code>String</code>
* against.
* @return <code>true</code> if the <code>String </code>are equal;
* <code>false</code> otherwise.
* @see java.lang.String#compareTo(java.lang.String)
* @see java.lang.String#equalsIgnoreCase(java.lang.String)
*/
public native boolean equals(Object anObject);
/*
* The original Java version
*
*public boolean equals(Object anObject) {
* if (this == anObject) {
* return true;
* }
* if (anObject instanceof String) {
* String anotherString = (String)anObject;
* int n = count;
* if (n == anotherString.count) {
* char v1[] = value;
* char v2[] = anotherString.value;
* int i = offset;
* int j = anotherString.offset;
* while (n-- != 0) {
* if (v1[i++] != v2[j++]) {
* return false;
* }
* }
* return true;
* }
* }
* return false;
*}
*/
/**
* Returns <tt>true</tt> if and only if this <tt>String</tt> represents
* the same sequence of characters as the specified <tt>StringBuffer</tt>.
*
* @param sb the <tt>StringBuffer</tt> to compare to.
* @return <tt>true</tt> if and only if this <tt>String</tt> represents
* the same sequence of characters as the specified
* <tt>StringBuffer</tt>, otherwise <tt>false</tt>.
* @since 1.4
*/
public boolean contentEquals(StringBuffer sb) {
synchronized(sb) {
if (count != sb.length())
return false;
char v1[] = value;
char v2[] = sb.getValue();
int i = offset;
int j = 0;
int n = count;
while (n-- != 0) {
if (v1[i++] != v2[j++])
return false;
}
}
return true;
}
/*
* The original Java version
*
*public boolean equals(Object anObject) {
* if (this == anObject) {
* return true;
* }
* if (anObject instanceof String) {
* String anotherString = (String)anObject;
* int n = count;
* if (n == anotherString.count) {
* char v1[] = value;
* char v2[] = anotherString.value;
* int i = offset;
* int j = anotherString.offset;
* while (n-- != 0) {
* if (v1[i++] != v2[j++]) {
* return false;
* }
* }
* return true;
* }
* }
* return false;
*}
*/
/**
* Compares this <code>String</code> to another <code>String</code>,
* 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</code> and <code>c2</code> 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>==</code> operator).
* <li>Applying the method {@link java.lang.Character#toUpperCase(char)}
* to each character produces the same result.
* <li>Applying the method {@link java.lang.Character#toLowerCase(char)}
* to each character produces the same result.</ul>
*
* @param anotherString the <code>String</code> to compare this
* <code>String</code> against.
* @return <code>true</code> if the argument is not <code>null</code>
* and the <code>String</code>s are equal,
* ignoring case; <code>false</code> otherwise.
* @see #equals(Object)
* @see java.lang.Character#toLowerCase(char)
* @see java.lang.Character#toUpperCase(char)
*/
public boolean equalsIgnoreCase(String anotherString) {
return (this == anotherString) ? true :
(anotherString != null) && (anotherString.count == count) &&
regionMatches(true, 0, anotherString, 0, count);
}
/**
* Compares two strings lexicographically.
* The comparison is based on the Unicode value of each character in
* the strings. The character sequence represented by this
* <code>String</code> object is compared lexicographically to the
* character sequence represented by the argument string. The result is
* a negative integer if this <code>String</code> object
* lexicographically precedes the argument string. The result is a
* positive integer if this <code>String</code> object lexicographically
* follows the argument string. The result is zero if the strings
* are equal; <code>compareTo</code> returns <code>0</code> exactly when
* the {@link #equals(Object)} method would return <code>true</code>.
* <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 < operator, lexicographically precedes the
* other string. In this case, <code>compareTo</code> returns the
* difference of the two character values at position <code>k</code> in
* the two string -- that is, the value:
* <blockquote><pre>
* this.charAt(k)-anotherString.charAt(k)
* </pre></blockquote>
* If there is no index position at which they differ, then the shorter
* string lexicographically precedes the longer string. In this case,
* <code>compareTo</code> returns the difference of the lengths of the
* strings -- that is, the value:
* <blockquote><pre>
* this.length()-anotherString.length()
* </pre></blockquote>
*
* @param anotherString the <code>String</code> to be compared.
* @return the value <code>0</code> if the argument string is equal to
* this string; a value less than <code>0</code> if this string
* is lexicographically less than the string argument; and a
* value greater than <code>0</code> if this string is
* lexicographically greater than the string argument.
*/
public native int compareTo(String anotherString);
/*
* The Java version of compare()
*
*public int compareTo(String anotherString) {
* int len1 = count;
* int len2 = anotherString.count;
* int n = Math.min(len1, len2);
* char v1[] = value;
* char v2[] = anotherString.value;
* int i = offset;
* int j = anotherString.offset;
*
* if (i == j) {
* int k = i;
* int lim = n + i;
* while (k < lim) {
* char c1 = v1[k];
* char c2 = v2[k];
* if (c1 != c2) {
* return c1 - c2;
* }
* k++;
* }
* } else {
* while (n-- != 0) {
* char c1 = v1[i++];
* char c2 = v2[j++];
* if (c1 != c2) {
* return c1 - c2;
* }
* }
* }
* return len1 - len2;
*}
*/
/**
* Compares this String to another Object. If the Object is a String,
* this function behaves like <code>compareTo(String)</code>. Otherwise,
* it throws a <code>ClassCastException</code> (as Strings are comparable
* only to other Strings).
*
* @param o the <code>Object</code> to be compared.
* @return the value <code>0</code> if the argument is a string
* lexicographically equal to this string; a value less than
* <code>0</code> if the argument is a string lexicographically
* greater than this string; and a value greater than
* <code>0</code> if the argument is a string lexicographically
* less than this string.
* @exception <code>ClassCastException</code> if the argument is not a
* <code>String</code>.
* @see java.lang.Comparable
* @since 1.2
*/
public int compareTo(Object o) {
return compareTo((String)o);
}
/**
* A Comparator that orders <code>String</code> objects as by
* <code>compareToIgnoreCase</code>. 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 java.text package provides <em>Collators</em> to allow
* locale-sensitive ordering.
*
* @see java.text.Collator#compare(String, String)
* @since 1.2
*/
public static final Comparator CASE_INSENSITIVE_ORDER
= new CaseInsensitiveComparator();
private static class CaseInsensitiveComparator
implements Comparator, java.io.Serializable {
// use serialVersionUID from JDK 1.2.2 for interoperability
private static final long serialVersionUID = 8575799808933029326L;
public int compare(Object o1, Object o2) {
String s1 = (String) o1;
String s2 = (String) o2;
int n1=s1.length(), n2=s2.length();
for (int i1=0, i2=0; i1<n1 && i2<n2; i1++, i2++) {
char c1 = s1.charAt(i1);
char c2 = s2.charAt(i2);
if (c1 != c2) {
c1 = Character.toUpperCase(c1);
c2 = Character.toUpperCase(c2);
if (c1 != c2) {
c1 = Character.toLowerCase(c1);
c2 = Character.toLowerCase(c2);
if (c1 != c2) {
return c1 - c2;
}
}
}
}
return n1 - n2;
}
}
/**
* Compares two strings lexicographically, ignoring case
* differences. This method returns an integer whose sign is that of
* calling <code>compareTo</code> with normalized versions of the strings
* where case differences have been eliminated by calling
* <code>Character.toLowerCase(Character.toUpperCase(character))</code> on
* each character.
* <p>
* Note that this method does <em>not</em> take locale into account,
* and will result in an unsatisfactory ordering for certain locales.
* The java.text package provides <em>collators</em> to allow
* locale-sensitive ordering.
*
* @param str the <code>String</code> to be compared.
* @return a negative integer, zero, or a positive integer as the
* the specified String is greater than, equal to, or less
* than this String, ignoring case considerations.
* @see java.text.Collator#compare(String, String)
* @since 1.2
*/
public int compareToIgnoreCase(String str) {
return CASE_INSENSITIVE_ORDER.compare(this, str);
}
/**
* Tests if two string regions are equal.
* <p>
* A substring of this <tt>String</tt> object is compared to a substring
* of the argument other. The result is true if these substrings
* represent identical character sequences. The substring of this
* <tt>String</tt> object to be compared begins at index <tt>toffset</tt>
* and has length <tt>len</tt>. The substring of other to be compared
* begins at index <tt>ooffset</tt> and has length <tt>len</tt>. The
* result is <tt>false</tt> if and only if at least one of the following
* is true:
* <ul><li><tt>toffset</tt> is negative.
* <li><tt>ooffset</tt> is negative.
* <li><tt>toffset+len</tt> is greater than the length of this
* <tt>String</tt> object.
* <li><tt>ooffset+len</tt> is greater than the length of the other
* argument.
* <li>There is some nonnegative integer <i>k</i> less than <tt>len</tt>
* such that:
* <tt>this.charAt(toffset+<i>k</i>) != other.charAt(ooffset+<i>k</i>)</tt>
* </ul>
*
* @param toffset the starting offset of the subregion in this string.
* @param other the string argument.
* @param ooffset the starting offset of the subregion in the string
* argument.
* @param len the number of characters to compare.
* @return <code>true</code> if the specified subregion of this string
* exactly matches the specified subregion of the string argument;
* <code>false</code> otherwise.
*/
public boolean regionMatches(int toffset, String other, int ooffset,
int len) {
char ta[] = value;
int to = offset + toffset;
char pa[] = other.value;
int po = other.offset + ooffset;
// Note: toffset, ooffset, or len might be near -1>>>1.
if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len)
|| (ooffset > (long)other.count - len)) {
return false;
}
while (len-- > 0) {
if (ta[to++] != pa[po++]) {
return false;
}
}
return true;
}
/**
* Tests if two string regions are equal.
* <p>
* A substring of this <tt>String</tt> object is compared to a substring
* of the argument <tt>other</tt>. The result is <tt>true</tt> if these
* substrings represent character sequences that are the same, ignoring
* case if and only if <tt>ignoreCase</tt> is true. The substring of
* this <tt>String</tt> object to be compared begins at index
* <tt>toffset</tt> and has length <tt>len</tt>. The substring of
* <tt>other</tt> to be compared begins at index <tt>ooffset</tt> and
* has length <tt>len</tt>. The result is <tt>false</tt> if and only if
* at least one of the following is true:
* <ul><li><tt>toffset</tt> is negative.
* <li><tt>ooffset</tt> is negative.
* <li><tt>toffset+len</tt> is greater than the length of this
* <tt>String</tt> object.
* <li><tt>ooffset+len</tt> is greater than the length of the other
* argument.
* <li><tt>ignoreCase</tt> is <tt>false</tt> and there is some nonnegative
* integer <i>k</i> less than <tt>len</tt> such that:
* <blockquote><pre>
* this.charAt(toffset+k) != other.charAt(ooffset+k)
* </pre></blockquote>
* <li><tt>ignoreCase</tt> is <tt>true</tt> and there is some nonnegative
* integer <i>k</i> less than <tt>len</tt> such that:
* <blockquote><pre>
* Character.toLowerCase(this.charAt(toffset+k)) !=
Character.toLowerCase(other.charAt(ooffset+k))
* </pre></blockquote>
* and:
* <blockquote><pre>
* Character.toUpperCase(this.charAt(toffset+k)) !=
* Character.toUpperCase(other.charAt(ooffset+k))
* </pre></blockquote>
* </ul>
*
* @param ignoreCase if <code>true</code>, ignore case when comparing
* characters.
* @param toffset the starting offset of the subregion in this
* string.
* @param other the string argument.
* @param ooffset the starting offset of the subregion in the string
* argument.
* @param len the number of characters to compare.
* @return <code>true</code> if the specified subregion of this string
* matches the specified subregion of the string argument;
* <code>false</code> otherwise. Whether the matching is exact
* or case insensitive depends on the <code>ignoreCase</code>
* argument.
*/
public boolean regionMatches(boolean ignoreCase, int toffset,
String other, int ooffset, int len) {
char ta[] = value;
int to = offset + toffset;
char pa[] = other.value;
int po = other.offset + ooffset;
// Note: toffset, ooffset, or len might be near -1>>>1.
if ((ooffset < 0) || (toffset < 0) || (toffset > (long)count - len) ||
(ooffset > (long)other.count - len)) {
return false;
}
while (len-- > 0) {
char c1 = ta[to++];
char c2 = pa[po++];
if (c1 == c2) {
continue;
}
if (ignoreCase) {
// If characters don't match but case may be ignored,
// try converting both characters to uppercase.
// If the results match, then the comparison scan should
// continue.
char u1 = Character.toUpperCase(c1);
char u2 = Character.toUpperCase(c2);
if (u1 == u2) {
continue;
}
// Unfortunately, conversion to uppercase does not work properly
// for the Georgian alphabet, which has strange rules about case
// conversion. So we need to make one last check before
// exiting.
if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) {
continue;
}
}
return false;
}
return true;
}
/**
* Tests if this string starts with the specified prefix beginning
* a specified index.
*
* @param prefix the prefix.
* @param toffset where to begin looking in the string.
* @return <code>true</code> if the character sequence represented by the
* argument is a prefix of the substring of this object starting
* at index <code>toffset</code>; <code>false</code> otherwise.
* The result is <code>false</code> if <code>toffset</code> is
* negative or greater than the length of this
* <code>String</code> object; otherwise the result is the same
* as the result of the expression
* <pre>
* this.subString(toffset).startsWith(prefix)
* </pre>
*/
public boolean startsWith(String prefix, int toffset) {
char ta[] = value;
int to = offset + toffset;
char pa[] = prefix.value;
int po = prefix.offset;
int pc = prefix.count;
// Note: toffset might be near -1>>>1.
if ((toffset < 0) || (toffset > count - pc)) {
return false;
}
while (--pc >= 0) {
if (ta[to++] != pa[po++]) {
return false;
}
}
return true;
}
/**
* Tests if this string starts with the specified prefix.
*
* @param prefix the prefix.
* @return <code>true</code> if the character sequence represented by the
* argument is a prefix of the character sequence represented by
* this string; <code>false</code> otherwise.
* Note also that <code>true</code> will be returned if the
* argument is an empty string or is equal to this
* <code>String</code> object as determined by the
* {@link #equals(Object)} method.
* @since 1. 0
*/
public boolean startsWith(String prefix) {
return startsWith(prefix, 0);
}
/**
* Tests if this string ends with the specified suffix.
*
* @param suffix the suffix.
* @return <code>true</code> if the character sequence represented by the
* argument is a suffix of the character sequence represented by
* this object; <code>false</code> otherwise. Note that the
* result will be <code>true</code> if the argument is the
* empty string or is equal to this <code>String</code> object
* as determined by the {@link #equals(Object)} method.
*/
public boolean endsWith(String suffix) {
return startsWith(suffix, count - suffix.count);
}
/**
* Returns a hash code for this string. The hash code for a
* <code>String</code> object is computed as
* <blockquote><pre>
* s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
* </pre></blockquote>
* using <code>int</code> arithmetic, where <code>s[i]</code> is the
* <i>i</i>th character of the string, <code>n</code> is the length of
* the string, and <code>^</code> indicates exponentiation.
* (The hash value of the empty string is zero.)
*
* @return a hash code value for this object.
*/
public native int hashCode();
/*
* Original Java version
*
*public int hashCode() {
* int h = 0;
* int off = offset;
* char val[] = value;
* int len = count;
*
* for (int i = 0; i < len; i++)
* h = 31*h + val[off++];
*
*
* return h;
*}
*/
/**
* Returns the index within this string of the first occurrence of the
* specified character. If a character with value <code>ch</code> occurs
* in the character sequence represented by this <code>String</code>
* object, then the index of the first such occurrence is returned --
* that is, the smallest value <i>k</i> such that:
* <blockquote><pre>
* this.charAt(<i>k</i>) == ch
* </pre></blockquote>
* is <code>true</code>. If no such character occurs in this string,
* then <code>-1</code> is returned.
*
* @param ch a character.
* @return the index of the first occurrence of the character in the
* character sequence represented by this object, or
* <code>-1</code> if the character does not occur.
*/
public native int indexOf(int ch);
/*
* The original Java version
*
*public int indexOf(int ch) {
* return indexOf(ch, 0);
*}
*/
/**
* Code shared by String and StringBuffer to do searches. The
* source is the character array being searched, and the target
* is the string being searched for.
*
* @param source the characters being searched.
* @param sourceOffset offset of the source string.
* @param sourceCount count of the source string.
* @param target the characters being searched for.
* @param targetOffset offset of the target string.
* @param targetCount count of the target string.
* @param fromIndex the index to begin searching from.
*/
static int indexOf(char[] source, int sourceOffset, int sourceCount,
char[] target, int targetOffset, int targetCount,
int fromIndex) {
if (fromIndex >= sourceCount) {
return (targetCount == 0 ? sourceCount : -1);
}
if (fromIndex < 0) {
fromIndex = 0;
}
if (targetCount == 0) {
return fromIndex;
}
char first = target[targetOffset];
int i = sourceOffset + fromIndex;
int max = sourceOffset + (sourceCount - targetCount);
startSearchForFirstChar:
while (true) {
/* Look for first character. */
while (i <= max && source[i] != first) {
i++;
}
if (i > max) {
return -1;
}
/* Found first character, now look at the rest of v2 */
int j = i + 1;
int end = j + targetCount - 1;
int k = targetOffset + 1;
while (j < end) {
if (source[j++] != target[k++]) {
i++;
/* Look for str's first char again. */
continue startSearchForFirstChar;
}
}
return i - sourceOffset; /* Found whole string. */
}
}
/*
* The original Java version
*
*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</code> occurs in the character
* sequence represented by this <code>String</code> object at an index
* no smaller than <code>fromIndex</code>, then the index of the first
* such occurrence is returned--that is, the smallest value <i>k</i>
* such that:
* <blockquote><pre>
* (this.charAt(<i>k</i>) == ch) && (<i>k</i> >= fromIndex)
* </pre></blockquote>
* is true. If no such character occurs in this string at or after
* position <code>fromIndex</code>, then <code>-1</code> is returned.
* <p>
* There is no restriction on the value of <code>fromIndex</code>. If it
* is negative, it has the same effect as if it were zero: this entire
* string may be searched. If it is greater than the length of this
* string, it has the same effect as if it were equal to the length of
* this string: <code>-1</code> is returned.
*
* @param ch a character.
* @param fromIndex the index to start the search from.
* @return the index of the first occurrence of the character in the
* character sequence represented by this object that is greater
* than or equal to <code>fromIndex</code>, or <code>-1</code>
* if the character does not occur.
*/
public native int indexOf(int ch, int fromIndex);
/*
* The original Java version
*
*public int indexOf(int ch, int fromIndex) {
* int max = offset + count;
* char v[] = value;
*
* if (fromIndex < 0) {
* fromIndex = 0;
* } else if (fromIndex >= count) {
* // Note: fromIndex might be near -1>>>1.
* return -1;
* }
* for (int i = offset + fromIndex ; i < max ; i++) {
* if (v[i] == ch) {
* return i - offset;
* }
* }
* return -1;
*}
*/
/**
* Returns the index within this string of the last occurrence of the
* specified character. That is, the index returned is the largest
* value <i>k</i> such that:
* <blockquote><pre>
* this.charAt(<i>k</i>) == ch
* </pre></blockquote>
* is true.
* The String is searched backwards starting at the last character.
*
* @param ch a character.
* @return the index of the last occurrence of the character in the
* character sequence represented by this object, or
* <code>-1</code> if the character does not occur.
*/
public int lastIndexOf(int ch) {
return lastIndexOf(ch, count - 1);
}
/**
* Returns the index within this string of the last occurrence of the
* specified character, searching backward starting at the specified
* index. That is, the index returned is the largest value <i>k</i>
* such that:
* <blockquote><pre>
* this.charAt(k) == ch) && (k <= fromIndex)
* </pre></blockquote>
* is true.
*
* @param ch a character.
* @param fromIndex the index to start the search from. There is no
* restriction on the value of <code>fromIndex</code>. If it is
* greater than or equal to the length of this string, it has
* the same effect as if it were equal to one less than the
* length of this string: this entire string may be searched.
* If it is negative, it has the same effect as if it were -1:
* -1 is returned.
* @return the index of the last occurrence of the character in the
* character sequence represented by this object that is less
* than or equal to <code>fromIndex</code>, or <code>-1</code>
* if the character does not occur before that point.
*/
public int lastIndexOf(int ch, int fromIndex) {
int min = offset;
char v[] = value;
for (int i = offset + ((fromIndex >= count) ? count - 1 : fromIndex) ; i >= min ; i--) {
if (v[i] == ch) {
return i - offset;
}
}
return -1;
}
/**
* Returns the index within this string of the first occurrence of the
* specified substring. The integer returned is the smallest value
* <i>k</i> such that:
* <blockquote><pre>
* this.startsWith(str, <i>k</i>)
* </pre></blockquote>
* is <code>true</code>.
*
* @param str any string.
* @return if the string argument occurs as a substring within this
* object, then the index of the first character of the first
* such substring is returned; if it does not occur as a
* substring, <code>-1</code> is returned.
*/
public native int indexOf(String str);
/*
* The original Java version
*
*public int indexOf(String str) {
* return indexOf(str, 0);
*}
*/
/**
* Returns the index within this string of the first occurrence of the
* specified substring, starting at the specified index. The integer
* returned is the smallest value <tt>k</tt> for which:
* <blockquote><pre>
* k >= Math.min(fromIndex, str.length()) && this.startsWith(str, k)
* </pre></blockquote>
* If no such value of <i>k</i> exists, then -1 is returned.
*
* @param str the substring for which to search.
* @param fromIndex the index from which to start the search.
* @return the index within this string of the first occurrence of the
* specified substring, starting at the specified index.
*/
public native int indexOf(String str, int fromIndex);
/*
* The original Java version
*
*public int indexOf(String str, int fromIndex) {
* char v1[] = value;
* char v2[] = str.value;
* int max = offset + (count - str.count);
* if (fromIndex >= count) {
* if (count == 0 && fromIndex == 0 && str.count == 0) {
* /* There is an empty string at index 0 in an empty string.
* return 0;
* }
* /* Note: fromIndex might be near -1>>>1
* return -1;
* }
* if (fromIndex < 0) {
* fromIndex = 0;
* }
* if (str.count == 0) {
* return fromIndex;
* }
*
* int strOffset = str.offset;
* char first = v2[strOffset];
* int i = offset + fromIndex;
*
*startSearchForFirstChar:
* while (true) {
*
* /* Look for first character.
* while (i <= max && v1[i] != first) {
* i++;
* }
* if (i > max) {
* return -1;
* }
*
* /* Found first character, now look at the rest of v2
* int j = i + 1;
* int end = j + str.count - 1;
* int k = strOffset + 1;
* while (j < end) {
* if (v1[j++] != v2[k++]) {
* i++;
* /* Look for str's first char again.
* continue startSearchForFirstChar;
* }
* }
* return i - offset; /* Found whole string.
* }
*}
*/
/**
* Returns the index within this string of the rightmost occurrence
* of the specified substring. The rightmost empty string "" is
* considered to occur at the index value <code>this.length()</code>.
* The returned index is the largest value <i>k</i> such that
* <blockquote><pre>
* this.startsWith(str, k)
* </pre></blockquote>
* is true.
*
* @param str the substring to search for.
* @return if the string argument occurs one or more times as a substring
* within this object, then the index of the first character of
* the last such substring is returned. If it does not occur as
* a substring, <code>-1</code> is returned.
*/
public int lastIndexOf(String str) {
return lastIndexOf(str, count);
}
/**
* Returns the index within this string of the last occurrence of the
* specified substring, searching backward starting at the specified index.
* The integer returned is the largest value <i>k</i> such that:
* <blockquote><pre>
* k <= Math.min(fromIndex, str.length()) && this.startsWith(str, k)
* </pre></blockquote>
* If no such value of <i>k</i> exists, then -1 is returned.
*
* @param str the substring to search for.
* @param fromIndex the index to start the search from.
* @return the index within this string of the last occurrence of the
* specified substring.
*/
public int lastIndexOf(String str, int fromIndex) {
return lastIndexOf(value, offset, count,
str.value, str.offset, str.count, fromIndex);
}
/**
* Code shared by String and StringBuffer to do searches. The
* source is the character array being searched, and the target
* is the string being searched for.
*
* @param source the characters being searched.
* @param sourceOffset offset of the source string.
* @param sourceCount count of the source string.
* @param target the characters being searched for.
* @param targetOffset offset of the target string.
* @param targetCount count of the target string.
* @param fromIndex the index to begin searching from.
*/
static int lastIndexOf(char[] source, int sourceOffset, int sourceCount,
char[] target, int targetOffset, int targetCount,
int fromIndex) {
/*
* Check arguments; return immediately where possible. For
* consistency, don't check for null str.
*/
int rightIndex = sourceCount - targetCount;
if (fromIndex < 0) {
return -1;
}
if (fromIndex > rightIndex) {
fromIndex = rightIndex;
}
/* Empty string always matches. */
if (targetCount == 0) {
return fromIndex;
}
int strLastIndex = targetOffset + targetCount - 1;
char strLastChar = target[strLastIndex];
int min = sourceOffset + targetCount - 1;
int i = min + fromIndex;
startSearchForLastChar:
while (true) {
while (i >= min && source[i] != strLastChar) {
i--;
}
if (i < min) {
return -1;
}
int j = i - 1;
int start = j - (targetCount - 1);
int k = strLastIndex - 1;
while (j > start) {
if (source[j--] != target[k--]) {
i--;
continue startSearchForLastChar;
}
}
return start - sourceOffset + 1;
}
}
/**
* Returns a new string that is a substring of this string. The
* substring begins with the character at the specified index and
* extends to the end of this string. <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</code> is negative or larger than the
* length of this <code>String</code> object.
*/
public String substring(int beginIndex) {
return substring(beginIndex, count);
}
/**
* Returns a new string that is a substring of this string. The
* substring begins at the specified <code>beginIndex</code> and
* extends to the character at index <code>endIndex - 1</code>.
* Thus the length of the substring is <code>endIndex-beginIndex</code>.
* <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</code> is negative, or
* <code>endIndex</code> is larger than the length of
* this <code>String</code> object, or
* <code>beginIndex</code> is larger than
* <code>endIndex</code>.
*/
public String substring(int beginIndex, int endIndex) {
if (beginIndex < 0) {
throw new StringIndexOutOfBoundsException(beginIndex);
}
if (endIndex > count) {
throw new StringIndexOutOfBoundsException(endIndex);
}
if (beginIndex > endIndex) {
throw new StringIndexOutOfBoundsException(endIndex - beginIndex);
}
return ((beginIndex == 0) && (endIndex == count)) ? this :
new String(offset + beginIndex, endIndex - beginIndex, value);
}
/**
* Returns a new character sequence that is a subsequence of this sequence.
*
* <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>
*
* This method is defined so that the <tt>String</tt> class can implement
* the {@link CharSequence} interface. </p>
*
* @param beginIndex the begin index, inclusive.
* @param endIndex the end index, exclusive.
* @return the specified subsequence.
*
* @throws IndexOutOfBoundsException
* if <tt>beginIndex</tt> or <tt>endIndex</tt> are negative,
* if <tt>endIndex</tt> is greater than <tt>length()</tt>,
* or if <tt>beginIndex</tt> is greater than <tt>startIndex</tt>
*
* @since 1.4
* @spec JSR-51
*/
public CharSequence subSequence(int beginIndex, int endIndex) {
return this.substring(beginIndex, endIndex);
}
/**
* Concatenates the specified string to the end of this string.
* <p>
* If the length of the argument string is <code>0</code>, then this
* <code>String</code> object is returned. Otherwise, a new
* <code>String</code> object is created, representing a character
* sequence that is the concatenation of the character sequence
* represented by this <code>String</code> object and the character
* sequence represented by the argument string.<p>
* Examples:
* <blockquote><pre>
* "cares".concat("s") returns "caress"
* "to".concat("get").concat("her") returns "together"
* </pre></blockquote>
*
* @param str the <code>String</code> that is concatenated to the end
* of this <code>String</code>.
* @return a string that represents the concatenation of this object's
* characters followed by the string argument's characters.
*/
public String concat(String str) {
int otherLen = str.length();
if (otherLen == 0) {
return this;
}
char buf[] = new char[count + otherLen];
getChars(0, count, buf, 0);
str.getChars(0, otherLen, buf, count);
return new String(0, count + otherLen, buf);
}
/**
* Returns a new string resulting from replacing all occurrences of
* <code>oldChar</code> in this string with <code>newChar</code>.
* <p>
* If the character <code>oldChar</code> does not occur in the
* character sequence represented by this <code>String</code> object,
* then a reference to this <code>String</code> object is returned.
* Otherwise, a new <code>String</code> object is created that
* represents a character sequence identical to the character sequence
* represented by this <code>String</code> object, except that every
* occurrence of <code>oldChar</code> is replaced by an occurrence
* of <code>newChar</code>.
* <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</code> with <code>newChar</code>.
*/
public String replace(char oldChar, char newChar) {
if (oldChar != newChar) {
int len = count;
int i = -1;
char[] val = value; /* avoid getfield opcode */
int off = offset; /* avoid getfield opcode */
while (++i < len) {
if (val[off + i] == oldChar) {
break;
}
}
if (i < len) {
char buf[] = new char[len];
for (int j = 0 ; j < i ; j++) {
buf[j] = val[off+j];
}
while (i < len) {
char c = val[off + i];
buf[i] = (c == oldChar) ? newChar : c;
i++;
}
return new String(0, len, buf);
}
}
return this;
}
/**
* Tells whether or not this string matches the given <a
* href="../util/regex/Pattern.html#sum">regular expression</a>.
*
* <p> An invocation of this method of the form
* <i>str</i><tt>.matches(</tt><i>regex</i><tt>)</tt> yields exactly the
* same result as the expression
*
* <blockquote><tt> {@link java.util.regex.Pattern}.{@link
* java.util.regex.Pattern#matches(String,CharSequence)
* matches}(</tt><i>regex</i><tt>,</tt> <i>str</i><tt>)</tt></blockquote>
*
* @param regex
* the regular expression to which this string is to be matched
*
* @return <tt>true</tt> if, and only if, this string matches the
* given regular expression
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
* @spec JSR-51
*/
/*
public boolean matches(String regex) {
return Pattern.matches(regex, this);
}
*/
/**
* 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><tt>.replaceFirst(</tt><i>regex</i><tt>,</tt> <i>repl</i><tt>)</tt>
* yields exactly the same result as the expression
*
* <blockquote><tt>
* {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile
* compile}(</tt><i>regex</i><tt>).{@link
* java.util.regex.Pattern#matcher(java.lang.CharSequence)
* matcher}(</tt><i>str</i><tt>).{@link java.util.regex.Matcher#replaceFirst
* replaceFirst}(</tt><i>repl</i><tt>)</tt></blockquote>
*
* @param regex
* the regular expression to which this string is to be matched
*
* @return The resulting <tt>String</tt>
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
* @spec JSR-51
*/
/*
public String replaceFirst(String regex, String replacement) {
return Pattern.compile(regex).matcher(this).replaceFirst(replacement);
}
*/
/**
* Replaces each substring of this string that matches the given <a
* href="../util/regex/Pattern.html#sum">regular expression</a> with the
* given replacement.
*
* <p> An invocation of this method of the form
* <i>str</i><tt>.replaceAll(</tt><i>regex</i><tt>,</tt> <i>repl</i><tt>)</tt>
* yields exactly the same result as the expression
*
* <blockquote><tt>
* {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile
* compile}(</tt><i>regex</i><tt>).{@link
* java.util.regex.Pattern#matcher(java.lang.CharSequence)
* matcher}(</tt><i>str</i><tt>).{@link java.util.regex.Matcher#replaceAll
* replaceAll}(</tt><i>repl</i><tt>)</tt></blockquote>
*
* @param regex
* the regular expression to which this string is to be matched
*
* @return The resulting <tt>String</tt>
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
* @spec JSR-51
*/
/*
public String replaceAll(String regex, String replacement) {
return Pattern.compile(regex).matcher(this).replaceAll(replacement);
}
*/
/**
* Splits this string around matches of the given <a
* href="{@docRoot}/java/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> The <tt>limit</tt> parameter controls the number of times the
* pattern is applied and therefore affects the length of the resulting
* array. If the limit <i>n</i> is greater than zero then the pattern
* will be applied at most <i>n</i> - 1 times, the array's
* length will be no greater than <i>n</i>, and the array's last entry
* will contain all input beyond the last matched delimiter. If <i>n</i>
* is non-positive then the pattern will be applied as many times as
* possible and the array can have any length. If <i>n</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> The string <tt>"boo:and:foo"</tt>, for example, yields the
* following results with these parameters:
*
* <blockquote><table cellpadding=1 cellspacing=0 summary="Split example showing regex, limit, and result">
* <tr>
* <th>Regex</th>
* <th>Limit</th>
* <th>Result</th>
* </tr>
* <tr><td align=center>:</td>
* <td align=center>2</td>
* <td><tt>{ "boo", "and:foo" }</tt></td></tr>
* <tr><td align=center>:</td>
* <td align=center>5</td>
* <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
* <tr><td align=center>:</td>
* <td align=center>-2</td>
* <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
* <tr><td align=center>o</td>
* <td align=center>5</td>
* <td><tt>{ "b", "", ":and:f", "", "" }</tt></td></tr>
* <tr><td align=center>o</td>
* <td align=center>-2</td>
* <td><tt>{ "b", "", ":and:f", "", "" }</tt></td></tr>
* <tr><td align=center>o</td>
* <td align=center>0</td>
* <td><tt>{ "b", "", ":and:f" }</tt></td></tr>
* </table></blockquote>
*
* <p> An invocation of this method of the form
* <i>str.</i><tt>split(</tt><i>regex</i><tt>,</tt> <i>n</i><tt>)</tt>
* yields the same result as the expression
*
* <blockquote>
* {@link java.util.regex.Pattern}.{@link java.util.regex.Pattern#compile
* compile}<tt>(</tt><i>regex</i><tt>)</tt>.{@link
* java.util.regex.Pattern#split(java.lang.CharSequence,int)
* split}<tt>(</tt><i>str</i><tt>,</tt> <i>n</i><tt>)</tt>
* </blockquote>
*
*
* @param regex
* the delimiting regular expression
*
* @param limit
* the result threshold, as described above
*
* @return the array of strings computed by splitting this string
* around matches of the given regular expression
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
* @spec JSR-51
*/
/*
public String[] split(String regex, int limit) {
return Pattern.compile(regex).split(this, limit);
}
*/
/**
* Splits this string around matches of the given <a
* href="{@docRoot}/java/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 <tt>"boo:and:foo"</tt>, for example, yields the following
* results with these expressions:
*
* <blockquote><table cellpadding=1 cellspacing=0 summary="Split examples showing regex and result">
* <tr>
* <th>Regex</th>
* <th>Result</th>
* </tr>
* <tr><td align=center>:</td>
* <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
* <tr><td align=center>o</td>
* <td><tt>{ "b", "", ":and:f" }</tt></td></tr>
* </table></blockquote>
*
*
* @param regex
* the delimiting regular expression
*
* @return the array of strings computed by splitting this string
* around matches of the given regular expression
*
* @throws PatternSyntaxException
* if the regular expression's syntax is invalid
*
* @see java.util.regex.Pattern
*
* @since 1.4
* @spec JSR-51
*/
/*
public String[] split(String regex) {
return split(regex, 0);
}
*/
/**
* Converts all of the characters in this <code>String</code> to lower
* case using the rules of the given <code>Locale</code>. Case mappings rely
* heavily on the Unicode specification's character data. Since case
* mappings are not always 1:1 char mappings, the resulting <code>String</code>
* may be a different length than the original <code>String</code>.
* <p>
* Examples of lowercase mappings are in the following table:
* <table border="1" summary="Lowercase mapping examples showing language code of locale, upper case, lower case, and description">
* <tr>
* <th>Language Code of Locale</th>
* <th>Upper Case</th>
* <th>Lower Case</th>
* <th>Description</th>
* </tr>
* <tr>
* <td>tr (Turkish)</td>
* <td>\u0130</td>
* <td>\u0069</td>
* <td>capital letter I with dot above -> small letter i</td>
* </tr>
* <tr>
* <td>tr (Turkish)</td>
* <td>\u0049</td>
* <td>\u0131</td>
* <td>capital letter I -> small letter dotless i </td>
* </tr>
* <tr>
* <td>(all)</td>
* <td>French Fries</td>
* <td>french fries</td>
* <td>lowercased all chars in String</td>
* </tr>
* <tr>
* <td>(all)</td>
* <td><img src="doc-files/capiota.gif" alt="capiota"><img src="doc-files/capchi.gif" alt="capchi">
* <img src="doc-files/captheta.gif" alt="captheta"><img src="doc-files/capupsil.gif" alt="capupsil">
* <img src="doc-files/capsigma.gif" alt="capsigma"></td>
* <td><img src="doc-files/iota.gif" alt="iota"><img src="doc-files/chi.gif" alt="chi">
* <img src="doc-files/theta.gif" alt="theta"><img src="doc-files/upsilon.gif" alt="upsilon">
* <img src="doc-files/sigma1.gif" alt="sigma"></td>
* <td>lowercased all chars in String</td>
* </tr>
* </table>
*
* @param locale use the case transformation rules for this locale
* @return the <code>String</code>, converted to lowercase.
* @see java.lang.String#toLowerCase()
* @see java.lang.String#toUpperCase()
* @see java.lang.String#toUpperCase(Locale)
* @since 1.1
*/
public String toLowerCase(Locale locale) {
if (locale == null)
throw new NullPointerException();
int len = count;
int off = offset;
char[] val = value;
int firstUpper;
/* Now check if there are any characters that need to be changed. */
scan: {
for (firstUpper = 0 ; firstUpper < len ; firstUpper++) {
char c = value[off+firstUpper];
if (c != Character.toLowerCase(c)) {break scan;}
}
return this;
}
char[] result = new char[count];
/* Just copy the first few lowerCase characters. */
CVM.copyCharArray(val, off, result, 0, firstUpper);
if (locale.getLanguage().equals("tr")) {
// special loop for Turkey
for (int i = firstUpper; i < len; ++i) {
char ch = val[off+i];
if (ch == 'I') {
result[i] = '\u0131'; // dotless small i
continue;
}
if (ch == '\u0130') { // dotted I
result[i] = 'i'; // dotted i
continue;
}
result[i] = Character.toLowerCase(ch);
}
} else {
// normal, fast loop
for (int i = firstUpper; i < len; ++i) {
result[i] = Character.toLowerCase(val[off+i]);
}
}
// Since we created the result array, just used the special
// internal constructor to avoid cloning the char array:
return new String(0, result.length, result);
}
/**
* Converts all of the characters in this <code>String</code> to lower
* case using the rules of the default locale. This is equivalent to calling
* <code>toLowerCase(Locale.getDefault())</code>.
* <p>
* @return the <code>String</code>, converted to lowercase.
* @see java.lang.String#toLowerCase(Locale)
*/
public String toLowerCase() {
return toLowerCase(Locale.getDefault());
}
/**
* Converts all of the characters in this <code>String</code> to upper
* case using the rules of the given <code>Locale</code>. Case mappings rely
* heavily on the Unicode specification's character data. Since case mappings
* are not always 1:1 char mappings, the resulting <code>String</code> may
* be a different length than the original <code>String</code>.
* <p>
* Examples of locale-sensitive and 1:M case mappings are in the following table.
* <p>
* <table border="1" summary="Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description.">
* <tr>
* <th>Language Code of Locale</th>
* <th>Lower Case</th>
* <th>Upper Case</th>
* <th>Description</th>
* </tr>
* <tr>
* <td>tr (Turkish)</td>
* <td>\u0069</td>
* <td>\u0130</td>
* <td>small letter i -> capital letter I with dot above</td>
* </tr>
* <tr>
* <td>tr (Turkish)</td>
* <td>\u0131</td>
* <td>\u0049</td>
* <td>small letter dotless i -> capital letter I</td>
* </tr>
* <tr>
* <td>(all)</td>
* <td>\u00df</td>
* <td>\u0053 \u0053</td>
* <td>small letter sharp s -> two letters: SS</td>
* </tr>
* <tr>
* <td>(all)</td>
* <td>Fahrvergnügen</td>
* <td>FAHRVERGNÜGEN</td>
* <td></td>
* </tr>
* </table>
* @param locale use the case transformation rules for this locale
* @return the <code>String</code>, converted to uppercase.
* @see java.lang.String#toUpperCase()
* @see java.lang.String#toLowerCase()
* @see java.lang.String#toLowerCase(Locale)
* @since 1.1
*/
public String toUpperCase(Locale locale) {
int len = count;
int off = offset;
char[] val = value;
int firstLower;
/* Now check if there are any characters that need changing. */
scan: {
char upperCaseChar;
char c;
for (firstLower = 0 ; firstLower < len ; firstLower++) {
c = value[off+firstLower];
upperCaseChar = Character.toUpperCaseEx(c);
if (upperCaseChar == Character.CHAR_ERROR || c != upperCaseChar) {
break scan;
}
}
return this;
}
char[] result = new char[len]; /* might grow! */
int resultOffset = 0; /* result grows, so i+resultOffset
* is the write location in result */
/* Just copy the first few upperCase characters. */
CVM.copyCharArray(val, off, result, 0, firstLower);
if (locale.getLanguage().equals("tr")) {
// special loop for Turkey
char[] upperCharArray;
char upperChar;
char ch;
for (int i = firstLower; i < len; ++i) {
ch = val[off+i];
if (ch == 'i') {
result[i+resultOffset] = '\u0130'; // dotted cap i
continue;
}
if (ch == '\u0131') { // dotless i
result[i+resultOffset] = 'I'; // cap I
continue;
}
upperChar = Character.toUpperCaseEx(ch);
if (upperChar == Character.CHAR_ERROR) {
upperCharArray = Character.toUpperCaseCharArray(ch);
/* Grow result. */
int mapLen = upperCharArray.length;
char[] result2 = new char[result.length + mapLen - 1];
CVM.copyCharArray(result, 0, result2, 0,
i + 1 + resultOffset);
for (int x=0; x<mapLen; ++x) {
result2[i+resultOffset++] = upperCharArray[x];
}
--resultOffset;
result = result2;
}
else {
result[i+resultOffset] = upperChar;
}
}
} else {
// normal, fast loop
char[] upperCharArray;
char upperChar;
char ch;
for (int i = firstLower; i < len; ++i) {
ch = val[off+i];
upperChar = Character.toUpperCaseEx(ch);
if (upperChar == Character.CHAR_ERROR) {
upperCharArray = Character.toUpperCaseCharArray(ch);
/* Grow result. */
int mapLen = upperCharArray.length;
char[] result2 = new char[result.length + mapLen - 1];
CVM.copyCharArray(result, 0, result2, 0,
i + 1 + resultOffset);
for (int x=0; x<mapLen; ++x) {
result2[i+resultOffset++] = upperCharArray[x];
}
--resultOffset;
result = result2;
}
else {
result[i+resultOffset] = upperChar;
}
}
}
// Since we created the result array, just used the special
// internal constructor to avoid cloning the char array:
return new String(0, result.length, result);
}
/**
* Converts all of the characters in this <code>String</code> to upper
* case using the rules of the default locale. This method is equivalent to
* <code>toUpperCase(Locale.getDefault())</code>.
* <p>
* @return the <code>String</code>, converted to uppercase.
* @see java.lang.String#toUpperCase(Locale)
*/
public String toUpperCase() {
return toUpperCase(Locale.getDefault());
}
/**
* Returns a copy of the string, with leading and trailing whitespace
* omitted.
* <p>
* If this <code>String</code> object represents an empty character
* sequence, or the first and last characters of character sequence
* represented by this <code>String</code> object both have codes
* greater than <code>'\u0020'</code> (the space character), then a
* reference to this <code>String</code> object is returned.
* <p>
* Otherwise, if there is no character with a code greater than
* <code>'\u0020'</code> in the string, then a new
* <code>String</code> object representing an empty string is created
* and returned.
* <p>
* Otherwise, let <i>k</i> be the index of the first character in the
* string whose code is greater than <code>'\u0020'</code>, and let
* <i>m</i> be the index of the last character in the string whose code
* is greater than <code>'\u0020'</code>. A new <code>String</code>
* object is created, representing the substring of this string that
* begins with the character at index <i>k</i> and ends with the
* character at index <i>m</i>-that is, the result of
* <code>this.substring(<i>k</i>, <i>m</i>+1)</code>.
* <p>
* This method may be used to trim
* {@link Character#isSpace(char) whitespace} from the beginning and end
* of a string; in fact, it trims all ASCII control characters as well.
*
* @return A copy of this string with leading and trailing white
* space removed, or this string if it has no leading or
* trailing white space.
*/
public String trim() {
int len = count;
int st = 0;
int off = offset; /* avoid getfield opcode */
char[] val = value; /* avoid getfield opcode */
while ((st < len) && (val[off + st] <= ' ')) {
st++;
}
while ((st < len) && (val[off + len - 1] <= ' ')) {
len--;
}
return ((st > 0) || (len < count)) ? substring(st, len) : this;
}
/**
* This object (which is already a string!) is itself returned.
*
* @return the string itself.
*/
public String toString() {
return this;
}
/**
* Converts this string to a new character array.
*
* @return a newly allocated character array whose length is the length
* of this string and whose contents are initialized to contain
* the character sequence represented by this string.
*/
public char[] toCharArray() {
char result[] = new char[count];
getChars(0, count, result, 0);
return result;
}
/**
* Returns the string representation of the <code>Object</code> argument.
*
* @param obj an <code>Object</code>.
* @return if the argument is <code>null</code>, then a string equal to
* <code>"null"</code>; otherwise, the value of
* <code>obj.toString()</code> is returned.
* @see java.lang.Object#toString()
*/
public static String valueOf(Object obj) {
return (obj == null) ? "null" : obj.toString();
}
/**
* Returns the string representation of the <code>char</code> array
* argument. The contents of the character array are copied; subsequent
* modification of the character array does not affect the newly
* created string.
*
* @param data a <code>char</code> array.
* @return a newly allocated string representing the same sequence of
* characters contained in the character array argument.
*/
public static String valueOf(char data[]) {
return new String(data);
}
/**
* Returns the string representation of a specific subarray of the
* <code>char</code> array argument.
* <p>
* The <code>offset</code> argument is the index of the first
* character of the subarray. The <code>count</code> argument
* specifies the length of the subarray. The contents of the subarray
* are copied; subsequent modification of the character array does not
* affect the newly created string.
*
* @param data the character array.
* @param offset the initial offset into the value of the
* <code>String</code>.
* @param count the length of the value of the <code>String</code>.
* @return a string representing the sequence of characters contained
* in the subarray of the character array argument.
* @exception IndexOutOfBoundsException if <code>offset</code> is
* negative, or <code>count</code> is negative, or
* <code>offset+count</code> is larger than
* <code>data.length</code>.
*/
public static String valueOf(char data[], int offset, int count) {
return new String(data, offset, count);
}
/**
* Returns a String that represents the character sequence in the
* array specified.
*
* @param data the character array.
* @param offset initial offset of the subarray.
* @param count length of the subarray.
* @return a <code>String</code> that contains the characters of the
* specified subarray of the character array.
*/
public static String copyValueOf(char data[], int offset, int count) {
// All public String constructors now copy the data.
return new String(data, offset, count);
}
/**
* Returns a String that represents the character sequence in the
* array specified.
*
* @param data the character array.
* @return a <code>String</code> that contains the characters of the
* character array.
*/
public static String copyValueOf(char data[]) {
return copyValueOf(data, 0, data.length);
}
/**
* Returns the string representation of the <code>boolean</code> argument.
*
* @param b a <code>boolean</code>.
* @return if the argument is <code>true</code>, a string equal to
* <code>"true"</code> is returned; otherwise, a string equal to
* <code>"false"</code> is returned.
*/
public static String valueOf(boolean b) {
return b ? "true" : "false";
}
/**
* Returns the string representation of the <code>char</code>
* argument.
*
* @param c a <code>char</code>.
* @return a string of length <code>1</code> containing
* as its single character the argument <code>c</code>.
*/
public static String valueOf(char c) {
char data[] = {c};
return new String(0, 1, data);
}
/**
* Returns the string representation of the <code>int</code> argument.
* <p>
* The representation is exactly the one returned by the
* <code>Integer.toString</code> method of one argument.
*
* @param i an <code>int</code>.
* @return a string representation of the <code>int</code> argument.
* @see java.lang.Integer#toString(int, int)
*/
public static String valueOf(int i) {
return Integer.toString(i, 10);
}
/**
* Returns the string representation of the <code>long</code> argument.
* <p>
* The representation is exactly the one returned by the
* <code>Long.toString</code> method of one argument.
*
* @param l a <code>long</code>.
* @return a string representation of the <code>long</code> argument.
* @see java.lang.Long#toString(long)
*/
public static String valueOf(long l) {
return Long.toString(l, 10);
}
/**
* Returns the string representation of the <code>float</code> argument.
* <p>
* The representation is exactly the one returned by the
* <code>Float.toString</code> method of one argument.
*
* @param f a <code>float</code>.
* @return a string representation of the <code>float</code> argument.
* @see java.lang.Float#toString(float)
*/
public static String valueOf(float f) {
return Float.toString(f);
}
/**
* Returns the string representation of the <code>double</code> argument.
* <p>
* The representation is exactly the one returned by the
* <code>Double.toString</code> method of one argument.
*
* @param d a <code>double</code>.
* @return a string representation of the <code>double</code> argument.
* @see java.lang.Double#toString(double)
*/
public static String valueOf(double d) {
return Double.toString(d);
}
/**
* Returns a canonical representation for the string object.
* <p>
* A pool of strings, initially empty, is maintained privately by the
* class <code>String</code>.
* <p>
* When the intern method is invoked, if the pool already contains a
* string equal to this <code>String</code> object as determined by
* the {@link #equals(Object)} method, then the string from the pool is
* returned. Otherwise, this <code>String</code> object is added to the
* pool and a reference to this <code>String</code> object is returned.
* <p>
* It follows that for any two strings <code>s</code> and <code>t</code>,
* <code>s.intern() == t.intern()</code> is <code>true</code>
* if and only if <code>s.equals(t)</code> is <code>true</code>.
* <p>
* All literal strings and string-valued constant expressions are
* interned. String literals are defined in §3.10.5 of the
* <a href="http://java.sun.com/docs/books/jls/html/">Java Language
* Specification</a>
*
* @return a string that has the same contents as this string, but is
* guaranteed to be from a pool of unique strings.
*/
public native String intern();
}