compact1, compact2, compact3

java.lang

Class String

java.lang.Object

java.lang.String

All Implemented Interfaces:

Serializable, CharSequence, Comparable<String>

public final class String
extends Object
implements Serializable, Comparable<String>, CharSequence

String represents immutable strings of (16-bit) unicode characters.

Supplementary characters are represented by pairs of 16-bit char values (surrogate pairs), i.e., UTF-16 encoding is used. Strings provide access to the single 16-bit char in the UTF-16 string, but also to the unicode code points.

Since:

1.0

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static Comparator<String>	CASE_INSENSITIVE_ORDER A comparator that is based on compareToIgnoreCase to order strings.

Constructor Summary

Constructors

Constructor and Description
String() Constructor for an empty string.
String(byte[] bytes) Constructs a new String by decoding the specified array of bytes using the platform's default charset.
String(byte[] bytes, Charset charset) Constructs a new String by decoding the specified array of bytes using the specified charset.
String(byte[] ascii, int hibyte) Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a Charset, charset name, or that use the platform's default charset.
String(byte[] bytes, int offset, int length) Constructs a new String by decoding the specified subarray of bytes using the platform's default charset.
String(byte[] bytes, int offset, int length, Charset charset) Constructs a new String by decoding the specified subarray of bytes using the specified charset.
String(byte[] ascii, int hibyte, int offset, int count) Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a Charset, charset name, or that use the platform's default charset.
String(byte[] bytes, int offset, int length, String charsetName) Constructs a new String by decoding the specified subarray of bytes using the specified charset.
String(byte[] bytes, String charsetName) Constructs a new String by decoding the specified array of bytes using the specified charset.
String(char[] value) Constructor for a string that contains the characters of a given character array.
String(char[] value, int offset, int count) Allocates a new String that contains characters from a subarray of the character array argument.
String(int[] codePoints, int offset, int count) Allocates a new String that contains characters from a subarray of the Unicode code point array argument.
String(String str) Constructor for a copy of a string.
String(StringBuffer sb) Constructor that creates a String object from the characters in a StringBuffer.
String(StringBuilder sb) Constructor that creates a String object from the characters in a StringBuilder.

Method Summary

Modifier and Type	Method and Description
char	charAt(int index) charAt returns the 16-bit character at the given index of this String.
int	codePointAt(int index) codePointAt
int	codePointBefore(int index) codePointBefore
int	codePointCount(int beginIndex, int endIndex) codePointCount
int	compareTo(String str) compareTo compares two strings lexicographically.
int	compareToIgnoreCase(String str) compareTo compares two strings lexicographically ignoring case.
String	concat(String str) concat creates a String that contains the concatenation of this string and another string.
boolean	contains(CharSequence s) Returns true if and only if this string contains the specified sequence of char values.
boolean	contentEquals(CharSequence cs) Compares this string to the specified CharSequence.
boolean	contentEquals(StringBuffer sb) Compares this string to the specified StringBuffer.
static String	copyValueOf(char[] data) copyValueOf returns a String containing the characters of the given character array.
static String	copyValueOf(char[] data, int offset, int count) copyValueOf creates a String that contains a subrange of the characters of a given character array.
boolean	endsWith(String suffix) Check if this string ends with the given suffix.
boolean	equals(Object o) Compare this String to another String.
boolean	equalsIgnoreCase(String str) Compare this String to another String ignoring case.
static String	format(Locale l, String format, Object... args) Returns a formatted string using the specified locale, format string, and arguments.
static String	format(String format, Object... args) Returns a formatted string using the specified format string and arguments.
byte[]	getBytes() getBytes converts the characters of this String to a sequence of bytes using the default encoding.
byte[]	getBytes(Charset encoding) Encodes this String into a sequence of bytes using the given charset, storing the result into a new byte array.
void	getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin) Deprecated. This method does not use the proper encoding. Use getBytes() to use the default encoding.
byte[]	getBytes(String charsetName) Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte array.
void	getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) getChars copies a subrange of the the characters of this string into a character array.
int	hashCode() hashCode calculates a hash code for this string.
int	indexOf(int ch) Find the first index of a given character or code point.
int	indexOf(int ch, int from) Find the first index of a given character or code point starting from a given findex.
int	indexOf(String str) Return the index of the first substring of this that is equal to str.
int	indexOf(String str, int from) Return the index of the first substring of this that is equal to str and that start at from or later.
protected int	indexOfCharSequence(CharSequence s, int from) Return the index of the first occurrence of a substring this that is equal to a CharSequence and that starts at from or later.
String	intern() intern interns this String.
boolean	isEmpty() Returns true if, and only if, length() is 0.
static String	join(CharSequence delimiter, CharSequence... elements) Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.
static String	join(CharSequence delimiter, Iterable<? extends CharSequence> elements) Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.
int	lastIndexOf(int ch) Find the last index of a given character or code point.
int	lastIndexOf(int ch, int from) Find the last index of a given character or code point starting from a given findex.
int	lastIndexOf(String str) Return the index of the last substring of this that is equal to str.
int	lastIndexOf(String str, int from) Return the index of the last substring of this that is equal to str and that is before a given index.
int	length() length returns the length of this string, i.e., the number of 16-bit characters contained in this string.
boolean	matches(String regex) Tells whether or not this string matches the given regular expression.
int	offsetByCodePoints(int index, int codePointOffset) offsetByCodePoints
boolean	regionMatches(boolean ignoreCase, int offset, String other, int ooffset, int len) Compare a region of this string with another string, optionally ignoring case.
boolean	regionMatches(int offset, String other, int ooffset, int len) Compare a region of this string with another string.
String	replace(char oldChar, char newChar) replace creates a new String that is equal to this String with a given character replaced by another character.
String	replace(CharSequence target, CharSequence replacement) Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.
String	replaceAll(String regex, String replacement) Replaces each substring of this string that matches the given regular expression with the given replacement.
String	replaceFirst(String regex, String replacement) Replaces the first substring of this string that matches the given regular expression with the given replacement.
String[]	split(String regex) Splits this string around matches of the given regular expression.
String[]	split(String regex, int limit) Splits this string around matches of the given regular expression.
boolean	startsWith(String prefix) Check if this string starts with the given prefix.
boolean	startsWith(String prefix, int offset) Check if this string starts with the given prefix from the given offset.
CharSequence	subSequence(int start, int end) subSequence creates a subsequence of this sequence.
String	substring(int from) Create a new String object with the contents of the suffix of this String starting at a given index.
String	substring(int from, int end) Create a new String objects with the contents of the substring of this String.
char[]	toCharArray() toCharArray allocates a new character array and copies the characters of this String into the array.
String	toLowerCase() toLowerCase converts this String to lower case using the default locale.
String	toLowerCase(Locale locale) Converts all of the characters in this String to lower case using the rules of the given Locale.
String	toString() toString creates a printable string that represents this object for debugging purposes.
String	toUpperCase() toUpperCase converts this String to lower case using the default locale.
String	toUpperCase(Locale locale) Converts all of the characters in this String to upper case using the rules of the given Locale.
String	trim() trim removes all leading and trailing characters with a code <= ' ' from this String.
static String	valueOf(boolean b) valueOf converts a boolean to a String.
static String	valueOf(char c) valueOf creates a one-character string containing the given character.
static String	valueOf(char[] data) valueOf returns a String containing the characters of the given character array.
static String	valueOf(char[] data, int offset, int count) valueOf creates a String that contains a subrange of the characters of a given character array.
static String	valueOf(double d) valueOf converts a double to a String
static String	valueOf(float f) valueOf converts a float to a String
static String	valueOf(int i) valueOf converts an int to a String.
static String	valueOf(long l) valueOf converts a long to a String
static String	valueOf(Object obj) valueOf returns a String created from a given object or null.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.CharSequence

chars, codePoints

Field Detail

CASE_INSENSITIVE_ORDER

public static final Comparator<String> CASE_INSENSITIVE_ORDER

A comparator that is based on compareToIgnoreCase to order strings.

This comparator is serializable.

Since:

1.2

Constructor Detail

String

public String()

Constructor for an empty string.

A more efficient way to obtain an empty string is by using the string constant "". Using this constructor will always create a new instance, i.e., perform a memory allocation.

String

public String(String str)

Constructor for a copy of a string.

Using this constructor will always create a new instance, i.e., perform a memory allocation. Unless a different instance is required, copying of a string is not needed.

Throws:

NullPointerException - if str is null.

Parameters:

str - string to copy

String

public String(char[] value)

Constructor for a string that contains the characters of a given character array.

ensure

   (   length() == value.length
    && for i in 0..value.length-1: charAt(i) == value[i])
 

Throws:

NullPointerException - if value is null.

Parameters:

value - character array

String

public String(char[] value,
              int offset,
              int count)

Allocates a new String that contains characters from a subarray of the character array argument. The offset argument is the index of the first character of the subarray and the count argument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.

Throws:

IndexOutOfBoundsException - If the offset and count arguments index characters outside the bounds of the value array

Parameters:

value - Array that is the source of characters

offset - The initial offset

count - The length

String

public String(int[] codePoints,
              int offset,
              int count)

Allocates a new String that contains characters from a subarray of the Unicode code point array argument. The offset argument is the index of the first code point of the subarray and the count argument specifies the length of the subarray. The contents of the subarray are converted to chars; subsequent modification of the int array does not affect the newly created string.

Throws:

IllegalArgumentException - If any invalid Unicode code point is found in codePoints

IndexOutOfBoundsException - If the offset and count arguments index characters outside the bounds of the codePoints array

Parameters:

codePoints - Array that is the source of Unicode code points

offset - The initial offset

count - The length

Since:

1.5

String

@Deprecated
public String(byte[] ascii,
                          int hibyte,
                          int offset,
                          int count)

Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a Charset, charset name, or that use the platform's default charset.

Allocates a new String constructed from a subarray of an array of 8-bit integer values.

The offset argument is the index of the first byte of the subarray, and the count argument specifies the length of the subarray.

Each byte in the subarray is converted to a char as specified in the method above.

Throws:

IndexOutOfBoundsException - If the offset or count argument is invalid

Parameters:

ascii - The bytes to be converted to characters

hibyte - The top 8 bits of each 16-bit Unicode code unit

offset - The initial offset

count - The length

See Also:

String(byte[], int), String(byte[], int, int, java.lang.String), String(byte[], int, int, java.nio.charset.Charset), String(byte[], int, int), String(byte[], java.lang.String), String(byte[], java.nio.charset.Charset), String(byte[])

String

@Deprecated
public String(byte[] ascii,
                          int hibyte)

Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a Charset, charset name, or that use the platform's default charset.

Allocates a new String containing characters constructed from an array of 8-bit integer values. Each character cin the resulting string is constructed from the corresponding component b in the byte array such that:

     c == (char)(((hibyte & 0xff) << 8)
                         | (b & 0xff))
 

Parameters:

ascii - The bytes to be converted to characters

hibyte - The top 8 bits of each 16-bit Unicode code unit

See Also:

String(byte[], int, int, java.lang.String), String(byte[], int, int, java.nio.charset.Charset), String(byte[], int, int), String(byte[], java.lang.String), String(byte[], java.nio.charset.Charset), String(byte[])

String

public String(byte[] bytes,
              int offset,
              int length,
              String charsetName)
       throws UnsupportedEncodingException

Constructs a new String by decoding the specified subarray of bytes using the specified charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the subarray.

The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. The CharsetDecoder class should be used when more control over the decoding process is required.

Throws:

UnsupportedEncodingException - If the named charset is not supported

IndexOutOfBoundsException - If the offset and length arguments index characters outside the bounds of the bytes array

Parameters:

bytes - The bytes to be decoded into characters

offset - The index of the first byte to decode

length - The number of bytes to decode

charsetName - The name of a supported charset

Since:

JDK1.1

String

public String(byte[] bytes,
              int offset,
              int length,
              Charset charset)

Constructs a new String by decoding the specified subarray of bytes using the specified charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the subarray.

This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. The CharsetDecoder class should be used when more control over the decoding process is required.

Throws:

IndexOutOfBoundsException - If the offset and length arguments index characters outside the bounds of the bytes array

Parameters:

bytes - The bytes to be decoded into characters

offset - The index of the first byte to decode

length - The number of bytes to decode

charset - The charset to be used to decode the bytes

Since:

1.6

String

public String(byte[] bytes,
              String charsetName)
       throws UnsupportedEncodingException

Constructs a new String by decoding the specified array of bytes using the specified charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the byte array.

The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. The CharsetDecoder class should be used when more control over the decoding process is required.

Throws:

UnsupportedEncodingException - If the named charset is not supported

Parameters:

bytes - The bytes to be decoded into characters

charsetName - The name of a supported charset

Since:

JDK1.1

String

public String(byte[] bytes,
              Charset charset)

Constructs a new String by decoding the specified array of bytes using the specified charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the byte array.

This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. The CharsetDecoder class should be used when more control over the decoding process is required.

Parameters:

bytes - The bytes to be decoded into characters

charset - The charset to be used to decode the bytes

Since:

1.6

String

public String(byte[] bytes,
              int offset,
              int length)

Constructs a new String by decoding the specified subarray of bytes using the platform's default charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the subarray.

The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The CharsetDecoder class should be used when more control over the decoding process is required.

Throws:

IndexOutOfBoundsException - If the offset and the length arguments index characters outside the bounds of the bytes array

Parameters:

bytes - The bytes to be decoded into characters

offset - The index of the first byte to decode

length - The number of bytes to decode

Since:

JDK1.1

String

public String(byte[] bytes)

Constructs a new String by decoding the specified array of bytes using the platform's default charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the byte array.

The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The CharsetDecoder class should be used when more control over the decoding process is required.

Parameters:

bytes - The bytes to be decoded into characters

Since:

JDK1.1

String

public String(StringBuffer sb)

Constructor that creates a String object from the characters in a StringBuffer.

ensure

   (   length() == sb.length()
    && for i in 0..length()-1: charAt(i) == sb.charAt(i))
 

Throws:

NullPointerException - if sb is null.

Parameters:

sb - the string buffer to take the characters from

String

public String(StringBuilder sb)

Constructor that creates a String object from the characters in a StringBuilder.

ensure

   (   length() == sb.length()
    && for i in 0..length()-1: charAt(i) == sb.charAt(i))
 

Throws:

NullPointerException - if sb is null.

Parameters:

sb - the string builder to take the characters from

Since:

1.5

Method Detail

length

public int length()

length returns the length of this string, i.e., the number of 16-bit characters contained in this string.

ensure

   (result >= 0)
 

Specified by:

length in interface CharSequence

Returns:

the length.

charAt

public char charAt(int index)

charAt returns the 16-bit character at the given index of this String.

implemented in C for better performance.

Specified by:

charAt in interface CharSequence

Throws:

IndexOutOfBoundsException - if index<0 or index >= length().

Parameters:

index - the position of the character to the read

Returns:

the character at position index

codePointAt

public int codePointAt(int index)

codePointAt

Parameters:

index -

Returns:

The code point value of the character at the index.

Since:

1.5

codePointBefore

public int codePointBefore(int index)

codePointBefore

Parameters:

index -

Returns:

The Unicode code point value before the given index.

Since:

1.5

codePointCount

public int codePointCount(int beginIndex,
                          int endIndex)

codePointCount

Parameters:

beginIndex -

endIndex -

Returns:

The number of Unicode code points in the specified text range.

Since:

1.5

offsetByCodePoints

public int offsetByCodePoints(int index,
                              int codePointOffset)

offsetByCodePoints

Parameters:

index -

codePointOffset -

Returns:

The index within this String.

Since:

1.5

getChars

public void getChars(int srcBegin,
                     int srcEnd,
                     char[] dst,
                     int dstBegin)

getChars copies a subrange of the the characters of this string into a character array.

ensure

   (for i in 0..srcEnd-srcBegin-1: charAt(srcBegin+i) == dst[dstBegin+i])
 

Throws:

IndexOutOfBoundsException - if srcBegin<0, srcBegin>srcEnd, srcEnd > length(), dstBegin<0 or dstBegin+srcEnd-srcBegin > dst.length;

NullPointerException - if dst is null

Parameters:

srcBegin - the index of the first character to copy

srcEnd - the index of the last character to copy

dst - (out!) the target character array

dstBegin - the index in the target array at which the first character should be stored.

getBytes

@Deprecated
public void getBytes(int srcBegin,
                                 int srcEnd,
                                 byte[] dst,
                                 int dstBegin)

Deprecated. This method does not use the proper encoding. Use getBytes() to use the default encoding.

getBytes copies a subrange of the the characters of this string into a byte array. The 16-bit characters are converted to 8-bit bytes by erasing the upper 8 bits.

ensure

   (for i in 0..srcEnd-srcBegin-1: (charAt(srcBegin+i)&0xff) == (dst[dstBegin+i]&0xff))
 

Throws:

IndexOutOfBoundsException - if srcBegin<0, srcBegin>srcEnd, srcEnd > length(), dstBegin<0 or dstBegin+srcEnd-srcBegin > dst.length;

NullPointerException - if dst is null

Parameters:

srcBegin - the index of the first character to copy

srcEnd - the index of the last character to copy

dst - (out!) the target byte array

dstBegin - the index in the target array at which the first character should be stored.

getBytes

public byte[] getBytes(String charsetName)
                throws UnsupportedEncodingException

Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte array.

The behavior of this method when this string cannot be encoded in the given charset is unspecified. The CharsetEncoder class should be used when more control over the encoding process is required.

Throws:

UnsupportedEncodingException - If the named charset is not supported

Parameters:

charsetName - The name of a supported charset

Returns:

The resultant byte array

Since:

JDK1.1

getBytes

public byte[] getBytes()

getBytes converts the characters of this String to a sequence of bytes using the default encoding. The bytes are then stored into a newly allocated byte array that is returned as the result of this method.

Characters that cannot be encoded with the default encoding will be replaced by '?'.

For JamaicaVM, the default encoding is ISO 8859-1.

Returns:

the new byte array

Since:

1.1

getBytes

public byte[] getBytes(Charset encoding)

Encodes this String into a sequence of bytes using the given charset, storing the result into a new byte array.

This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement byte array. The CharsetEncoder class should be used when more control over the encoding process is required.

Parameters:

encoding - The Charset to be used to encode the String

Returns:

The resultant byte array

Since:

1.6

equals

public boolean equals(Object o)

Compare this String to another String.

ensure

   (result == (   (anObject instanceof String)
               && (length() == ((String)o).length())
               && (for all i in 0..length()-1: charAt(i) == ((String)o).charAt(i)))
 

implemented in C for better performance.

Overrides:

equals in class Object

Parameters:

o - object

Returns:

true if this and o are equal strings.

See Also:

Object.hashCode(), HashMap

contentEquals

public boolean contentEquals(StringBuffer sb)

Compares this string to the specified StringBuffer. The result is true if and only if this String represents the same sequence of characters as the specified StringBuffer. This method synchronizes on the StringBuffer.

Parameters:

sb - The StringBuffer to compare this String against

Returns:

true if this String represents the same sequence of characters as the specified StringBuffer, false otherwise

Since:

1.4

contentEquals

public boolean contentEquals(CharSequence cs)

Compares this string to the specified CharSequence. The result is true if and only if this String represents the same sequence of char values as the specified sequence. Note that if the CharSequence is a StringBuffer then the method synchronizes on it.

Parameters:

cs - The sequence to compare this String against

Returns:

true if this String represents the same sequence of char values as the specified sequence, false otherwise

Since:

1.5

equalsIgnoreCase

public boolean equalsIgnoreCase(String str)

Compare this String to another String ignoring case. Two characters c1 and c2 are considered equal if

      (c1 == c2)
   || Character.toUpperCase(c1) == Character.toUpperCase(c2)
   || Character.toLowerCase(c1) == Character.toLowerCase(c2)
 

Parameters:

str - the string to compare to

Returns:

true if str!=null, length()==str.length() and all characters of this and str are equal ignoring case.

compareTo

public int compareTo(String str)

compareTo compares two strings lexicographically. The result is 0 if both strings are equal. Else, if the first character at which this and str differ is at index i, the result is charAt(i) - str.charAt(i). If both strings differ in length and are equal up to the last character of the shorter string, the result is length() - str.length().

implemented in C for better performance.

Specified by:

compareTo in interface Comparable<String>

Throws:

NullPointerException - if str==null

Parameters:

str - a string to compare to.

Returns:

0 if strings are equal, < 0 if this < str, > 0 if this > str.

compareToIgnoreCase

public int compareToIgnoreCase(String str)

compareTo compares two strings lexicographically ignoring case. The result is 0 if both strings are equal. Else, the result is < 0 or > 0, respectively, depending on whether this < str or this > str.

Case is ignored by converting each character c via nested calls to Character.toLowerCase(Character.toUpperCase(c)) before the comparison.

Throws:

NullPointerException - if str==null

Parameters:

str - a string to compare to.

Returns:

0 if strings are equal, < 0 if this < str, > 0 if this > str.

Since:

1.2

regionMatches

public boolean regionMatches(int offset,
                             String other,
                             int ooffset,
                             int len)

Compare a region of this string with another string.

Throws:

NullPointerException - if other is null.

Parameters:

offset - the index in this at which comparison should start.

other - the other String to compare with

ooffset - the index in other at which comparison should start.

len - the number of characters to compare.

Returns:

true iff for all i in 0..len-1: charAt(offset+i) == other.charAt(ooffset+i).

regionMatches

public boolean regionMatches(boolean ignoreCase,
                             int offset,
                             String other,
                             int ooffset,
                             int len)

Compare a region of this string with another string, optionally ignoring case. If ignoreCase==false, this is equal to regionMatches(offset,other,ooffset,len). Otherwise, two characters c1 and c2 are considered equal iff

      (c1 == c2)
   || Character.toUpperCase(c1) == Character.toUpperCase(c2)
   || Character.toLowerCase(c1) == Character.toLowerCase(c2)
 

Throws:

NullPointerException - if other is null.

Parameters:

ignoreCase - true to ignore case, false to compare characters directly.

offset - the index in this at which comparison should start.

other - the other String to compare with

ooffset - the index in other at which comparison should start.

len - the number of characters to compare.

Returns:

true iff for all i in 0..len-1: charAt(offset+i) equals (ignoring case if ignoreCase==true) other.charAt(ooffset+i).

startsWith

public boolean startsWith(String prefix,
                          int offset)

Check if this string starts with the given prefix from the given offset.

Throws:

NullPointerException - if prefix is null.

Parameters:

prefix - the prefix

offset - the offset in this where to start looking for the prefix

Returns:

true if for all i in 0..prefix.length()-1: charAt(offset+i) == prefix.charAt(i).

startsWith

public boolean startsWith(String prefix)

Check if this string starts with the given prefix.

Throws:

NullPointerException - if prefix is null.

Parameters:

prefix - the prefix

Returns:

true if for all i in 0..prefix.length()-1: charAt(i) == prefix.charAt(i).

Since:

1.0

endsWith

public boolean endsWith(String suffix)

Check if this string ends with the given suffix.

Throws:

NullPointerException - if suffix is null.

Parameters:

suffix - the suffix

Returns:

true if for all i in 0..suffix.length()-1: charAt(length()-suffix.length()+i) == suffix.charAt(i).

hashCode

public int hashCode()

hashCode calculates a hash code for this string. The hash code value calculations takes into account each single character. The value is

   charAt(0)*31**(length()-1) + charAt(1)*31**(length()-2) + ... + charAt(length()-1)
 

implemented in C for better performance.

Overrides:

hashCode in class Object

Returns:

the hashCode value

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

indexOf

public int indexOf(int ch)

Find the first index of a given character or code point.

ensure

   (   ((ch <= 0xffff && result == -1)
           IMPLIES for all i=0..length()-1: charAt(i) != ch)
    && ((ch <= 0xffff && result != -1)
           IMPLIES (   (charAt(result) == ch)
                    && for all i=0..result-1: charAt(i) != ch))
    && ((ch >  0xffff && result == -1)
           IMPLIES for all codepoint indices i: codePointAt(i) != ch)
    && ((ch >  0xffff && result != -1)
           IMPLIES (   (codePointAt(result) == ch)
                    && for all i=0..result-1: codePointAt(i) != ch)
 

Parameters:

ch - the character or code point

Returns:

the first index of ch in this String, -1 if ch does not occur in this string.

indexOf

public int indexOf(int ch,
                   int from)

Find the first index of a given character or code point starting from a given findex.

ensure

   (   ((ch <= 0xffff && result == -1)
           IMPLIES for all i=from..length()-1: charAt(i) != ch)
    && ((ch <= 0xffff && result != -1)
           IMPLIES (   (charAt(result) == ch)
                    && for all i=from..result-1: charAt(i) != ch))
    && ((ch >  0xffff && result == -1)
           IMPLIES for all codepoint indices i: codePointAt(i) != ch)
    && ((ch >  0xffff && result != -1)
           IMPLIES (   (codePointAt(result) == ch)
                    && for all i=from..result-1: codePointAt(i) != ch)
 

Parameters:

ch - the character or code point

Returns:

the first index of ch in this String, -1 if ch does not occur in this string.

lastIndexOf

public int lastIndexOf(int ch)

Find the last index of a given character or code point.

ensure

   (   ((ch <= 0xffff && result == -1)
           IMPLIES for all i=0..length()-1: charAt(i) != ch)
    && ((ch <= 0xffff && result != -1)
           IMPLIES (   (charAt(result) == ch)
                    && for all i=result+1..length()-1: charAt(i) != ch))
    && ((ch >  0xffff && result == -1)
           IMPLIES for all codepoint indices i: codePointAt(i) != ch)
    && ((ch >  0xffff && result != -1)
           IMPLIES (   (codePointAt(result) == ch)
                    && for all codepoint indices in i=result+1..length()-1: codePointAt(i) != ch)
 

Parameters:

ch - the character or code point

Returns:

the last index of ch in this String, -1 if ch does not occur in this string.

lastIndexOf

public int lastIndexOf(int ch,
                       int from)

Find the last index of a given character or code point starting from a given findex.

ensure

   (   ((ch <= 0xffff && result == -1)
           IMPLIES for all i=0..from: charAt(i) != ch)
    && ((ch <= 0xffff && result != -1)
           IMPLIES (   (charAt(result) == ch)
                    && for all i=0..from: charAt(i) != ch))
    && ((ch >  0xffff && result == -1)
           IMPLIES for all codepoint indices i in 0..from: codePointAt(i) != ch)
    && ((ch >  0xffff && result != -1)
           IMPLIES (   (codePointAt(result) == ch)
                    && for all i=0..from: codePointAt(i) != ch)
 

Parameters:

ch - the character or code point

Returns:

the first index of ch in this String, -1 if ch does not occur in this string.

indexOf

public int indexOf(String str)

Return the index of the first substring of this that is equal to str.

Throws:

NullPointerException - if str is null.

Parameters:

str - the required substring

Returns:

the index in this of the first substring found, -1 if this does not contain str as a substring.

indexOf

public int indexOf(String str,
                   int from)

Return the index of the first substring of this that is equal to str and that start at from or later.

ensure

   (result != -1 IMPLIES startWith(str,result));
 

implemented in C for better performance.

Throws:

NullPointerException - if str is null.

Parameters:

str - the required substring

from - the index to start to search for the substring.

Returns:

the index in this of the first substring found, -1 if this.substring(from) does not contain str as a substring.

lastIndexOf

public int lastIndexOf(String str)

Return the index of the last substring of this that is equal to str.

ensure

   (result != -1 IMPLIES startsWith(str,result) && result <= length());
 

Throws:

NullPointerException - if str is null.

Parameters:

str - the required substring

Returns:

the index in this of the last substring found, -1 if this does not contain str as a substring.

lastIndexOf

public int lastIndexOf(String str,
                       int from)

Return the index of the last substring of this that is equal to str and that is before a given index.

ensure

   (result != -1 IMPLIES startsWith(str,result) && result <= from && result <= length());
 

Throws:

NullPointerException - if str is null.

Parameters:

str - the required substring

from - the starting index.

Returns:

the index in this of the last substring found, -1 if this does not contain str as a substring.

substring

public String substring(int from)

Create a new String object with the contents of the suffix of this String starting at a given index.

ensure

   (   (result.length() == length()-from)
    && (for all i=0..result.length(): result.charAt(i) == charAt(from+i)));
 

Throws:

IndexOutOfBoundsException - if from<0 or from>length().

Parameters:

from - the starting index.

Returns:

a new String with the suffix of this starting at from.

substring

public String substring(int from,
                        int end)

Create a new String objects with the contents of the substring of this String.

ensure

   (   (result.length() == end-from)
    && (for all i=0..result.length(): result.charAt(i) == charAt(from+i)));
 

Throws:

IndexOutOfBoundsException - if from<0 or end>length() or end

Parameters:

from - the starting index (inclusive).

end - the end index (exclusive)..

Returns:

a new String with the the substring [from..end), or this if the substring would be equal to this.

subSequence

public CharSequence subSequence(int start,
                                int end)

subSequence creates a subsequence of this sequence.

This implementation of the interface method CharSequence.subSequence behaves exactly as substring(start,end).

Specified by:

subSequence in interface CharSequence

Throws:

IndexOutOfBoundsException - if start<0 || endlength().

Parameters:

start - the start position.

end - the end position.

Returns:

a subsequence

Since:

1.4

indexOfCharSequence

protected int indexOfCharSequence(CharSequence s,
                                  int from)

Return the index of the first occurrence of a substring this that is equal to a CharSequence and that starts at from or later.

ensure

   (result != -1 IMPLIES startsWith(s.toString(),result));
 

Throws:

NullPointerException - if s is null.

Parameters:

s - the required substring

from - the index to start to search for the substring.

Returns:

the index in this of the first substring found, -1 if this.substring(from) does not contain str as a substring.

concat

public String concat(String str)

concat creates a String that contains the concatenation of this string and another string.

For JamaicaVM, this returns this or str if str.length()==0 or this.length()==0, respectively.

ensure

   (   (result.length() == this.length()+str.length())
    && (for all i=0..this.length(): result.charAt(i         ) ==     charAt(i))
    && (for all i=0..str .length(): result.charAt(length()+i) == str.charAt(i)))
 

Throws:

NullPointerException - if str is null

Parameters:

str - the other string

Returns:

the concatenation of this and str.

replace

public String replace(char oldChar,
                      char newChar)

replace creates a new String that is equal to this String with a given character replaced by another character. If this does not contain the character that is to be replaced, this is returned without modification.

ensure

   (   (result.length() == length())
    && (for all i=0..length()-1: result.charAt(i) == (charAt(i)==oldChar ? newChar: charAt(i))))
 

Parameters:

oldChar - the character to be replaced

newChar - the character oldChar is to be replaced with

Returns:

a String equal to this with oldChar replaced by newChar

matches

public boolean matches(String regex)

Tells whether or not this string matches the given regular expression.

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

Pattern.matches(regex, str)

Throws:

PatternSyntaxException - if the regular expression's syntax is invalid

Parameters:

regex - the regular expression to which this string is to be matched

Returns:

true if, and only if, this string matches the given regular expression

Since:

1.4

See Also:

Pattern

contains

public boolean contains(CharSequence s)

Returns true if and only if this string contains the specified sequence of char values.

Parameters:

s - the sequence to search for

Returns:

true if this string contains s, false otherwise

Since:

1.5

replaceFirst

public String replaceFirst(String regex,
                           String replacement)

Replaces the first substring of this string that matches the given regular expression with the given replacement.

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

Pattern.compile(regex).matcher(str).replaceFirst(repl)

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; see Matcher.replaceFirst(java.lang.String). Use Matcher.quoteReplacement(java.lang.String) to suppress the special meaning of these characters, if desired.

Throws:

PatternSyntaxException - if the regular expression's syntax is invalid

Parameters:

regex - the regular expression to which this string is to be matched

replacement - the string to be substituted for the first match

Returns:

The resulting String

Since:

1.4

See Also:

Pattern

replaceAll

public String replaceAll(String regex,
                         String replacement)

Replaces each substring of this string that matches the given regular expression with the given replacement.

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

Pattern.compile(regex).matcher(str).replaceAll(repl)

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; see Matcher.replaceAll. Use Matcher.quoteReplacement(java.lang.String) to suppress the special meaning of these characters, if desired.

Throws:

PatternSyntaxException - if the regular expression's syntax is invalid

Parameters:

regex - the regular expression to which this string is to be matched

replacement - the string to be substituted for each match

Returns:

The resulting String

Since:

1.4

See Also:

Pattern

replace

public String replace(CharSequence target,
                      CharSequence 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".

Parameters:

target - The sequence of char values to be replaced

replacement - The replacement sequence of char values

Returns:

The resulting string

Since:

1.5

split

public String[] split(String regex,
                      int limit)

Splits this string around matches of the given regular expression.

The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string. The substrings in the array are in the order in which they occur in this string. If the expression does not match any part of the input then the resulting array has just one element, namely this string.

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

The limit parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array. If the limit n is greater than zero then the pattern will be applied at most n - 1 times, the array's length will be no greater than n, and the array's last entry will contain all input beyond the last matched delimiter. If n is non-positive then the pattern will be applied as many times as possible and the array can have any length. If n is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

The string "boo:and:foo", for example, yields the following results with these parameters:

Regex	Limit	Result
:	2	{ "boo", "and:foo" }
:	5	{ "boo", "and", "foo" }
:	-2	{ "boo", "and", "foo" }
o	5	{ "b", "", ":and:f", "", "" }
o	-2	{ "b", "", ":and:f", "", "" }
o	0	{ "b", "", ":and:f" }

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

Pattern.compile(regex).split(str, n)

Throws:

PatternSyntaxException - if the regular expression's syntax is invalid

Parameters:

regex - the delimiting regular expression

limit - the result threshold, as described above

Returns:

the array of strings computed by splitting this string around matches of the given regular expression

Since:

1.4

See Also:

Pattern

split

public String[] split(String regex)

Splits this string around matches of the given regular expression.

This method works as if by invoking the two-argument split method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.

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

Regex	Result
:	{ "boo", "and", "foo" }
o	{ "b", "", ":and:f" }

Throws:

PatternSyntaxException - if the regular expression's syntax is invalid

Parameters:

regex - the delimiting regular expression

Returns:

the array of strings computed by splitting this string around matches of the given regular expression

Since:

1.4

See Also:

Pattern

join

public static String join(CharSequence delimiter,
                          CharSequence... elements)

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.

For example,

     String message = String.join("-", "Java", "is", "cool");
     // message returned is: "Java-is-cool"
 

Note that if an element is null, then "null" is added.

Throws:

NullPointerException - If delimiter or elements is null

Parameters:

delimiter - the delimiter that separates each element

elements - the elements to join together.

Returns:

a new String that is composed of the elements separated by the delimiter

Since:

1.8

See Also:

StringJoiner

join

public static String join(CharSequence delimiter,
                          Iterable<? extends CharSequence> elements)

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.

For example,

     List<String> strings = new LinkedList<>();
     strings.add("Java");strings.add("is");
     strings.add("cool");
     String message = String.join(" ", strings);
     //message returned is: "Java is cool"

     Set<String> strings = new LinkedHashSet<>();
     strings.add("Java"); strings.add("is");
     strings.add("very"); strings.add("cool");
     String message = String.join("-", strings);
     //message returned is: "Java-is-very-cool"
 

Note that if an individual element is null, then "null" is added.

Throws:

NullPointerException - If delimiter or elements is null

Parameters:

delimiter - a sequence of characters that is used to separate each of the elements in the resulting String

elements - an Iterable that will have its elements joined together.

Returns:

a new String that is composed from the elements argument

Since:

1.8

See Also:

join(CharSequence,CharSequence...), StringJoiner

toLowerCase

public String toLowerCase(Locale locale)

Converts all of the characters in this String to lower case using the rules of the given Locale. Case mapping is based on the Unicode Standard version specified by the Character class. Since case mappings are not always 1:1 char mappings, the resulting String may be a different length than the original String.

Examples of lowercase mappings are in the following table:

Language Code of Locale	Upper Case	Lower Case	Description
tr (Turkish)	\u0130	\u0069	capital letter I with dot above -> small letter i
tr (Turkish)	\u0049	\u0131	capital letter I -> small letter dotless i
(all)	French Fries	french fries	lowercased all chars in String
(all)			lowercased all chars in String

Parameters:

locale - use the case transformation rules for this locale

Returns:

the String, converted to lowercase.

Since:

1.1

See Also:

toLowerCase(), toUpperCase(), toUpperCase(Locale)

toLowerCase

public String toLowerCase()

toLowerCase converts this String to lower case using the default locale.

This is equivalent to toLowerCase(Locale.getDefault()).

Since:

1.1

toUpperCase

public String toUpperCase(Locale locale)

Converts all of the characters in this String to upper case using the rules of the given Locale. Case mapping is based on the Unicode Standard version specified by the Character class. Since case mappings are not always 1:1 char mappings, the resulting String may be a different length than the original String.

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

Language Code of Locale	Lower Case	Upper Case	Description
tr (Turkish)	\u0069	\u0130	small letter i -> capital letter I with dot above
tr (Turkish)	\u0131	\u0049	small letter dotless i -> capital letter I
(all)	\u00df	\u0053 \u0053	small letter sharp s -> two letters: SS
(all)	Fahrvergnügen	FAHRVERGNÜGEN

Parameters:

locale - use the case transformation rules for this locale

Returns:

the String, converted to uppercase.

Since:

1.1

See Also:

toUpperCase(), toLowerCase(), toLowerCase(Locale)

toUpperCase

public String toUpperCase()

toUpperCase converts this String to lower case using the default locale.

This is equivalent to toUpperCase(Locale.getDefault()).

Since:

1.1

trim

public String trim()

trim removes all leading and trailing characters with a code <= ' ' from this String.

Returns:

a String with leading and trailing control and white space characters removed, this is there are no such characters.

toString

public String toString()

toString creates a printable string that represents this object for debugging purposes.

Specified by:

toString in interface CharSequence

Overrides:

toString in class Object

Returns:

this

toCharArray

public char[] toCharArray()

toCharArray allocates a new character array and copies the characters of this String into the array.

ensure

   (   result.length == length()
    && (for all i=0..length()-1: result[i] == charAt(i)))
 

Returns:

the new character array.

valueOf

public static String valueOf(Object obj)

valueOf returns a String created from a given object or null.

Parameters:

obj - an object or null

Returns:

(obj == null) ? "null" : obj.toString()

valueOf

public static String valueOf(char[] data)

valueOf returns a String containing the characters of the given character array.

ensure

   (   result.length() == data.length
    && for i in 0..data.length-1: result.charAt(i) == data[i])
 

Throws:

NullPointerException - if data is null

Parameters:

data - the character array

Returns:

a new String containing the characters from data

copyValueOf

public static String copyValueOf(char[] data)

copyValueOf returns a String containing the characters of the given character array.

ensure

   (   result.length() == data.length
    && for i in 0..data.length-1: result.charAt(i) == data[i])
 

This is equivalent to valueOf(data)

Throws:

NullPointerException - if data is null

Parameters:

data - the character array

Returns:

a new String containing the characters from data

valueOf

public static String valueOf(char[] data,
                             int offset,
                             int count)

valueOf creates a String that contains a subrange of the characters of a given character array.

ensure

   (   result.length() == count
    && for i in 0..count-1: result.charAt(i) == data[offset+i])
 

Throws:

NullPointerException - if data is null.

IndexOutOfBoundsException - if count<0 or offset<0 or offset+count>data.length.

Parameters:

data - the character array

offset - the index of the first character to use in the string

count - the number of characters to use in the string.

copyValueOf

public static String copyValueOf(char[] data,
                                 int offset,
                                 int count)

copyValueOf creates a String that contains a subrange of the characters of a given character array.

ensure

   (   result.length() == count
    && for i in 0..count-1: result.charAt(i) == data[offset+i])
 

This is equivalent to valueOf(data,offset,count)

Throws:

NullPointerException - if data is null.

IndexOutOfBoundsException - if count<0 or offset<0 or offset+count>data.length.

Parameters:

data - the character array

offset - the index of the first character to use in the string

count - the number of characters to use in the string.

valueOf

public static String valueOf(boolean b)

valueOf converts a boolean to a String.

Parameters:

b - the boolean value

Returns:

b ? "true" : "false"

valueOf

public static String valueOf(char c)

valueOf creates a one-character string containing the given character.

A cache is used to avoid redundant allocations of the same string.

ensure

   (   result.length() == 1
    && result.charAt(0) == c);
 

Parameters:

c - the character

Returns:

a String of length 1 containing the character c.

valueOf

public static String valueOf(int i)

valueOf converts an int to a String.

Parameters:

i - an integer

Returns:

Integer.toString(i)

valueOf

public static String valueOf(long l)

valueOf converts a long to a String

Parameters:

l - a long

Returns:

Long.toString(l)

valueOf

public static String valueOf(float f)

valueOf converts a float to a String

Parameters:

f - a float

Returns:

Float.toString(f)

valueOf

public static String valueOf(double d)

valueOf converts a double to a String

Parameters:

d - a double

Returns:

Double.toString(d)

intern

public String intern()

intern interns this String. For any two Strings s1 and s2, the following holds:

   s1.equals(s2) <==> s1.intern() == s2.intern()
 

Note that String constants (such as "Hello") are automatically interned by the virtual machine, such that the following holds:

   s.equals("const string") <==> s.intern() == "const string"
 

intern() may be used for more efficient String equality comparison and to safe memory if many equal Strings are in use simulteneously.

However, intern() requires additional memory for each intern()ed String, such that this function should not be used without reason.

intern()ed Strings that become unused by the application will be reclaimed using weak references when the system memory runs low.

For JamaicaVM: intern() needs to allocate memory on the heap. If this function is called from within RTSJ's scoped memory (ScopedMemory), this method will anyway perform an allocation on the heap for the resulting intern()ed String. The resulting String will have its MemoryArea set to ImmortalMemory such that intern()ed Strings can be used even by code that cannot access heap objects (such as NoHeapRealtimeThread). However, the memory for intern()ed strings will be reclaimed after the last reference to such a string is deleted.

Returns:

a unique String for which result.equals(this) and MemoryArea.getMemoryArea(result)==ImmortalMemory.instance().

format

public static String format(String format,
                            Object... args)

Returns a formatted string using the specified format string and arguments.

The locale always used is the one returned by Locale.getDefault().

Throws:

IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.

NullPointerException - If the format is null

Parameters:

format - A format string

args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by the Java Virtual Machine Specification. The behaviour on a null argument depends on the conversion.

Returns:

A formatted string

Since:

1.5

See Also:

Formatter

format

public static String format(Locale l,
                            String format,
                            Object... args)

Returns a formatted string using the specified locale, format string, and arguments.

Throws:

IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification

NullPointerException - If the format is null

Parameters:

l - The locale to apply during formatting. If l is null then no localization is applied.

format - A format string

args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by the Java Virtual Machine Specification. The behaviour on a null argument depends on the conversion.

Returns:

A formatted string

Since:

1.5

See Also:

Formatter

isEmpty

public boolean isEmpty()

Returns true if, and only if, length() is 0.

Returns:

true if length() is 0, otherwise false

Since:

1.6