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JavaTM 2 Platform Standard Ed. 5.0 |
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java.lang
Class String
java.lang.Objectjava.lang.String
- All Implemented Interfaces:
- Serializable, CharSequence, Comparable<String>
public final class String
- extends Object
- implements Serializable, Comparable<String>, CharSequence
- extends Object
The String
class represents character strings. All
string literals in Java programs, such as "abc"
, are
implemented as instances of this class.
Strings are constant; their values cannot be changed after they are created. String buffers support mutable strings. Because String objects are immutable they can be shared. For example:
String str = "abc";
is equivalent to:
char data[] = {'a', 'b', 'c'}; String str = new String(data);
Here are some more examples of how strings can be used:
System.out.println("abc"); String cde = "cde"; System.out.println("abc" + cde); String c = "abc".substring(2,3); String d = cde.substring(1, 2);
The class String
includes methods for examining
individual characters of the sequence, for comparing strings, for
searching strings, for extracting substrings, and for creating a
copy of a string with all characters translated to uppercase or to
lowercase. Case mapping is based on the Unicode Standard version
specified by the Character
class.
The Java language provides special support for the string
concatenation operator ( + ), and for conversion of
other objects to strings. String concatenation is implemented
through the StringBuilder
(or StringBuffer
)
class and its append
method.
String conversions are implemented through the method
toString
, defined by Object
and
inherited by all classes in Java. For additional information on
string concatenation and conversion, see Gosling, Joy, and Steele,
The Java Language Specification.
Unless otherwise noted, passing a null argument to a constructor
or method in this class will cause a NullPointerException
to be
thrown.
A String
represents a string in the UTF-16 format
in which supplementary characters are represented by surrogate
pairs (see the section Unicode
Character Representations in the Character
class for
more information).
Index values refer to char
code units, so a supplementary
character uses two positions in a String
.
The String
class provides methods for dealing with
Unicode code points (i.e., characters), in addition to those for
dealing with Unicode code units (i.e., char
values).
- Since:
- JDK1.0
- See Also:
Object.toString()
,StringBuffer
,StringBuilder
,Charset
, Serialized Form
Field Summary | |
---|---|
static Comparator<String> |
CASE_INSENSITIVE_ORDER
A Comparator that orders String objects as by
compareToIgnoreCase . |
Constructor Summary | |
---|---|
String()
Initializes a newly created String object so that it
represents an empty character sequence. |
|
String(byte[] bytes)
Constructs a new String by decoding the specified array of bytes using the platform's default 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 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[] 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 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)
Allocates a new String so that it represents the
sequence of characters currently contained in the character array
argument. |
|
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 original)
Initializes a newly created String object so that it
represents the same sequence of characters as the argument; in other
words, the newly created string is a copy of the argument string. |
|
String(StringBuffer buffer)
Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. |
|
String(StringBuilder builder)
Allocates a new string that contains the sequence of characters currently contained in the string builder argument. |
Method Summary | |
---|---|
char |
charAt(int index)
Returns the char value at the
specified index. |
int |
codePointAt(int index)
Returns the character (Unicode code point) at the specified index. |
int |
codePointBefore(int index)
Returns the character (Unicode code point) before the specified index. |
int |
codePointCount(int beginIndex,
int endIndex)
Returns the number of Unicode code points in the specified text range of this String . |
int |
compareTo(String anotherString)
Compares two strings lexicographically. |
int |
compareToIgnoreCase(String str)
Compares two strings lexicographically, ignoring case differences. |
String |
concat(String str)
Concatenates the specified string to the end of this string. |
boolean |
contains(CharSequence s)
Returns true if and only if this string contains the specified sequence of char values. |
boolean |
contentEquals(CharSequence cs)
Returns true if and only if this String represents the same sequence of char values as the specified sequence. |
boolean |
contentEquals(StringBuffer sb)
Returns true if and only if this String represents the same sequence of characters as the specified StringBuffer. |
static String |
copyValueOf(char[] data)
Returns a String that represents the character sequence in the array specified. |
static String |
copyValueOf(char[] data,
int offset,
int count)
Returns a String that represents the character sequence in the array specified. |
boolean |
endsWith(String suffix)
Tests if this string ends with the specified suffix. |
boolean |
equals(Object anObject)
Compares this string to the specified object. |
boolean |
equalsIgnoreCase(String anotherString)
Compares this String to another String ,
ignoring case considerations. |
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()
Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array. |
void |
getBytes(int srcBegin,
int srcEnd,
byte[] dst,
int dstBegin)
Deprecated. This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via the getBytes() method, which uses the platform's default
charset. |
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)
Copies characters from this string into the destination character array. |
int |
hashCode()
Returns a hash code for this string. |
int |
indexOf(int ch)
Returns the index within this string of the first occurrence of the specified character. |
int |
indexOf(int ch,
int fromIndex)
Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index. |
int |
indexOf(String str)
Returns the index within this string of the first occurrence of the specified substring. |
int |
indexOf(String str,
int fromIndex)
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. |
String |
intern()
Returns a canonical representation for the string object. |
int |
lastIndexOf(int ch)
Returns the index within this string of the last occurrence of the specified character. |
int |
lastIndexOf(int ch,
int fromIndex)
Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. |
int |
lastIndexOf(String str)
Returns the index within this string of the rightmost occurrence of the specified substring. |
int |
lastIndexOf(String str,
int fromIndex)
Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index. |
int |
length()
Returns the length of this string. |
boolean |
matches(String regex)
Tells whether or not this string matches the given regular expression. |
int |
offsetByCodePoints(int index,
int codePointOffset)
Returns the index within this String that is
offset from the given index by
codePointOffset code points. |
boolean |
regionMatches(boolean ignoreCase,
int toffset,
String other,
int ooffset,
int len)
Tests if two string regions are equal. |
boolean |
regionMatches(int toffset,
String other,
int ooffset,
int len)
Tests if two string regions are equal. |
String |
replace(char oldChar,
char newChar)
Returns a new string resulting from replacing all occurrences of oldChar in this string with newChar . |
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)
Tests if this string starts with the specified prefix. |
boolean |
startsWith(String prefix,
int toffset)
Tests if this string starts with the specified prefix beginning a specified index. |
CharSequence |
subSequence(int beginIndex,
int endIndex)
Returns a new character sequence that is a subsequence of this sequence. |
String |
substring(int beginIndex)
Returns a new string that is a substring of this string. |
String |
substring(int beginIndex,
int endIndex)
Returns a new string that is a substring of this string. |
char[] |
toCharArray()
Converts this string to a new character array. |
String |
toLowerCase()
Converts all of the characters in this String to lower
case using the rules of 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()
This object (which is already a string!) is itself returned. |
String |
toUpperCase()
Converts all of the characters in this String to upper
case using the rules of 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()
Returns a copy of the string, with leading and trailing whitespace omitted. |
static String |
valueOf(boolean b)
Returns the string representation of the boolean argument. |
static String |
valueOf(char c)
Returns the string representation of the char
argument. |
static String |
valueOf(char[] data)
Returns the string representation of the char array
argument. |
static String |
valueOf(char[] data,
int offset,
int count)
Returns the string representation of a specific subarray of the char array argument. |
static String |
valueOf(double d)
Returns the string representation of the double argument. |
static String |
valueOf(float f)
Returns the string representation of the float argument. |
static String |
valueOf(int i)
Returns the string representation of the int argument. |
static String |
valueOf(long l)
Returns the string representation of the long argument. |
static String |
valueOf(Object obj)
Returns the string representation of the Object argument. |
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Field Detail |
---|
CASE_INSENSITIVE_ORDER
public static final Comparator<String> CASE_INSENSITIVE_ORDER
- A Comparator that orders
String
objects as bycompareToIgnoreCase
. This comparator is serializable.Note that this Comparator does not take locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package provides Collators to allow locale-sensitive ordering.
- Since:
- 1.2
- See Also:
Collator.compare(String, String)
Constructor Detail |
---|
String
public String()
- Initializes a newly created
String
object so that it represents an empty character sequence. Note that use of this constructor is unnecessary since Strings are immutable.
String
public String(String original)
- Initializes a newly created
String
object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string. Unless an explicit copy oforiginal
is needed, use of this constructor is unnecessary since Strings are immutable.- Parameters:
original
- aString
.
String
public String(char[] value)
- Allocates a new
String
so that it represents the sequence of characters currently contained in the character array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.- Parameters:
value
- the initial value of the string.
String
public String(char[] value, int offset, int count)
- Allocates a new
String
that contains characters from a subarray of the character array argument. Theoffset
argument is the index of the first character of the subarray and thecount
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.- Parameters:
value
- array that is the source of characters.offset
- the initial offset.count
- the length.- Throws:
IndexOutOfBoundsException
- if theoffset
andcount
arguments index characters outside the bounds of thevalue
array.
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. Theoffset
argument is the index of the first code point of the subarray and thecount
argument specifies the length of the subarray. The contents of the subarray are converted tochar
s; subsequent modification of theint
array does not affect the newly created string.- Parameters:
codePoints
- array that is the source of Unicode code points.offset
- the initial offset.count
- the length.- Throws:
IllegalArgumentException
- if any invalid Unicode code point is found incodePoints
IndexOutOfBoundsException
- if theoffset
andcount
arguments index characters outside the bounds of thecodePoints
array.- 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 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 thecount
argument specifies the length of the subarray.Each
byte
in the subarray is converted to achar
as specified in the method above.- Parameters:
ascii
- the bytes to be converted to characters.hibyte
- the top 8 bits of each 16-bit Unicode character.offset
- the initial offset.count
- the length.- Throws:
IndexOutOfBoundsException
- if theoffset
orcount
argument is invalid.- See Also:
String(byte[], int)
,String(byte[], int, int, java.lang.String)
,String(byte[], int, int)
,String(byte[], java.lang.String)
,String(byte[])
- Allocates a new
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 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 character.- See Also:
String(byte[], int, int, java.lang.String)
,String(byte[], int, int)
,String(byte[], java.lang.String)
,String(byte[])
- Allocates a new
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.- Parameters:
bytes
- the bytes to be decoded into charactersoffset
- the index of the first byte to decodelength
- the number of bytes to decodecharsetName
- the name of a supportedcharset
- Throws:
UnsupportedEncodingException
- if the named charset is not supportedIndexOutOfBoundsException
- if the offset and length arguments index characters outside the bounds of the bytes array- Since:
- JDK1.1
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.- Parameters:
bytes
- the bytes to be decoded into characterscharsetName
- the name of a supportedcharset
- Throws:
UnsupportedEncodingException
- If the named charset is not supported- Since:
- JDK1.1
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.- Parameters:
bytes
- the bytes to be decoded into charactersoffset
- the index of the first byte to decodelength
- the number of bytes to decode- Throws:
IndexOutOfBoundsException
- if theoffset
and thelength
arguments index characters outside the bounds of thebytes
array- 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 buffer)
- 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.
- Parameters:
buffer
- aStringBuffer
.
String
public String(StringBuilder builder)
- Allocates a new string that contains the sequence of characters
currently contained in the string builder argument. The contents of
the string builder are copied; subsequent modification of the string
builder does not affect the newly created string.
This constructor is provided to ease migration to
StringBuilder
. Obtaining a string from a string builder via thetoString
method is likely to run faster and is generally preferred.- Parameters:
builder
- aStringBuilder
- Since:
- 1.5
Method Detail |
---|
length
public int length()
- Returns the length of this string.
The length is equal to the number of 16-bit
Unicode characters in the string.
- Specified by:
length
in interfaceCharSequence
- Returns:
- the length of the sequence of characters represented by this object.
charAt
public char charAt(int index)
- Returns the
char
value at the specified index. An index ranges from0
tolength() - 1
. The firstchar
value of the sequence is at index0
, the next at index1
, and so on, as for array indexing.If the
char
value specified by the index is a surrogate, the surrogate value is returned.- Specified by:
charAt
in interfaceCharSequence
- Parameters:
index
- the index of thechar
value.- Returns:
- the
char
value at the specified index of this string. The firstchar
value is at index0
. - Throws:
IndexOutOfBoundsException
- if theindex
argument is negative or not less than the length of this string.
codePointAt
public int codePointAt(int index)
- Returns the character (Unicode code point) at the specified
index. The index refers to
char
values (Unicode code units) and ranges from0
tolength()
- 1
.If the
char
value specified at the given index is in the high-surrogate range, the following index is less than the length of thisString
, and thechar
value at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, thechar
value at the given index is returned.- Parameters:
index
- the index to thechar
values- Returns:
- the code point value of the character at the
index
- Throws:
IndexOutOfBoundsException
- if theindex
argument is negative or not less than the length of this string.- Since:
- 1.5
codePointBefore
public int codePointBefore(int index)
- Returns the character (Unicode code point) before the specified
index. The index refers to
char
values (Unicode code units) and ranges from1
tolength
.If the
char
value at(index - 1)
is in the low-surrogate range,(index - 2)
is not negative, and thechar
value at(index - 2)
is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If thechar
value atindex - 1
is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.- Parameters:
index
- the index following the code point that should be returned- Returns:
- the Unicode code point value before the given index.
- Throws:
IndexOutOfBoundsException
- if theindex
argument is less than 1 or greater than the length of this string.- Since:
- 1.5
codePointCount
public int codePointCount(int beginIndex, int endIndex)
- Returns the number of Unicode code points in the specified text
range of this
String
. The text range begins at the specifiedbeginIndex
and extends to thechar
at indexendIndex - 1
. Thus the length (inchar
s) of the text range isendIndex-beginIndex
. Unpaired surrogates within the text range count as one code point each.- Parameters:
beginIndex
- the index to the firstchar
of the text range.endIndex
- the index after the lastchar
of the text range.- Returns:
- the number of Unicode code points in the specified text range
- Throws:
IndexOutOfBoundsException
- if thebeginIndex
is negative, orendIndex
is larger than the length of thisString
, orbeginIndex
is larger thanendIndex
.- Since:
- 1.5
offsetByCodePoints
public int offsetByCodePoints(int index, int codePointOffset)
- Returns the index within this
String
that is offset from the givenindex
bycodePointOffset
code points. Unpaired surrogates within the text range given byindex
andcodePointOffset
count as one code point each.- Parameters:
index
- the index to be offsetcodePointOffset
- the offset in code points- Returns:
- the index within this
String
- Throws:
IndexOutOfBoundsException
- ifindex
is negative or larger then the length of thisString
, or ifcodePointOffset
is positive and the substring starting withindex
has fewer thancodePointOffset
code points, or ifcodePointOffset
is negative and the substring beforeindex
has fewer than the absolute value ofcodePointOffset
code points.- Since:
- 1.5
getChars
public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
- Copies characters from this string into the destination character
array.
The first character to be copied is at index
srcBegin
; the last character to be copied is at indexsrcEnd-1
(thus the total number of characters to be copied issrcEnd-srcBegin
). The characters are copied into the subarray ofdst
starting at indexdstBegin
and ending at index:dstbegin + (srcEnd-srcBegin) - 1
- Parameters:
srcBegin
- index of the first character in the string to copy.srcEnd
- index after the last character in the string to copy.dst
- the destination array.dstBegin
- the start offset in the destination array.- Throws:
IndexOutOfBoundsException
- If any of the following is true:srcBegin
is negative.srcBegin
is greater thansrcEnd
srcEnd
is greater than the length of this stringdstBegin
is negativedstBegin+(srcEnd-srcBegin)
is larger thandst.length
getBytes
@Deprecated public void getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin)
- Deprecated. This method does not properly convert characters into bytes.
As of JDK 1.1, the preferred way to do this is via the
getBytes()
method, which uses the platform's default charset.- Copies characters from this string into the destination byte array. Each byte receives the 8 low-order bits of the corresponding character. The eight high-order bits of each character are not copied and do not participate in the transfer in any way.
The first character to be copied is at index
srcBegin
; the last character to be copied is at indexsrcEnd-1
. The total number of characters to be copied issrcEnd-srcBegin
. The characters, converted to bytes, are copied into the subarray ofdst
starting at indexdstBegin
and ending at index:dstbegin + (srcEnd-srcBegin) - 1
- Parameters:
srcBegin
- index of the first character in the string to copy.srcEnd
- index after the last character in the string to copy.dst
- the destination array.dstBegin
- the start offset in the destination array.- Throws:
IndexOutOfBoundsException
- if any of the following is true:srcBegin
is negativesrcBegin
is greater thansrcEnd
srcEnd
is greater than the length of this StringdstBegin
is negativedstBegin+(srcEnd-srcBegin)
is larger thandst.length
- 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.
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.- Parameters:
charsetName
- the name of a supportedcharset
- Returns:
- The resultant byte array
- Throws:
UnsupportedEncodingException
- If the named charset is not supported- Since:
- JDK1.1
getBytes
public byte[] getBytes()
- Encodes this String into a sequence of bytes using the
platform's default charset, storing the result into a new byte array.
The behavior of this method when this string cannot be encoded in the default charset is unspecified. The
CharsetEncoder
class should be used when more control over the encoding process is required.- Returns:
- The resultant byte array
- Since:
- JDK1.1
equals
public boolean equals(Object anObject)
- Compares this string to the specified object.
The result is
true
if and only if the argument is notnull
and is aString
object that represents the same sequence of characters as this object.- Parameters:
anObject
- the object to compare thisString
against.- Returns:
true
if theString
are equal;false
otherwise.- See Also:
compareTo(java.lang.String)
,equalsIgnoreCase(java.lang.String)
contentEquals
public boolean contentEquals(StringBuffer sb)
- Returns true if and only if this String represents
the same sequence of characters as the specified StringBuffer.
- Parameters:
sb
- the StringBuffer to compare to.- Returns:
- true if and only if this String represents the same sequence of characters as the specified StringBuffer, otherwise false.
- Throws:
NullPointerException
- ifsb
isnull
- Since:
- 1.4
contentEquals
public boolean contentEquals(CharSequence cs)
- Returns true if and only if this String represents
the same sequence of char values as the specified sequence.
- Parameters:
cs
- the sequence to compare to.- Returns:
- true if and only if this String represents the same sequence of char values as the specified sequence, otherwise false.
- Throws:
NullPointerException
- ifcs
isnull
- Since:
- 1.5
equalsIgnoreCase
public boolean equalsIgnoreCase(String anotherString)
- Compares this
String
to anotherString
, ignoring case considerations. Two strings are considered equal ignoring case if they are of the same length, and corresponding characters in the two strings are equal ignoring case.Two characters
c1
andc2
are considered the same, ignoring case if at least one of the following is true:- The two characters are the same (as compared by the
==
operator). - Applying the method
Character.toUpperCase(char)
to each character produces the same result. - Applying the method
Character.toLowerCase(char)
to each character produces the same result.
- Parameters:
anotherString
- theString
to compare thisString
against.- Returns:
true
if the argument is notnull
and theString
s are equal, ignoring case;false
otherwise.- See Also:
equals(Object)
,Character.toLowerCase(char)
,Character.toUpperCase(char)
- The two characters are the same (as compared by the
compareTo
public int compareTo(String anotherString)
- Compares two strings lexicographically.
The comparison is based on the Unicode value of each character in
the strings. The character sequence represented by this
String
object is compared lexicographically to the character sequence represented by the argument string. The result is a negative integer if thisString
object lexicographically precedes the argument string. The result is a positive integer if thisString
object lexicographically follows the argument string. The result is zero if the strings are equal;compareTo
returns0
exactly when theequals(Object)
method would returntrue
.This is the definition of lexicographic ordering. If two strings are different, then either they have different characters at some index that is a valid index for both strings, or their lengths are different, or both. If they have different characters at one or more index positions, let k be the smallest such index; then the string whose character at position k has the smaller value, as determined by using the < operator, lexicographically precedes the other string. In this case,
compareTo
returns the difference of the two character values at positionk
in the two string -- that is, the value:
If there is no index position at which they differ, then the shorter string lexicographically precedes the longer string. In this case,this.charAt(k)-anotherString.charAt(k)
compareTo
returns the difference of the lengths of the strings -- that is, the value:this.length()-anotherString.length()
- Specified by:
compareTo
in interfaceComparable<String>
- Parameters:
anotherString
- theString
to be compared.- Returns:
- the value
0
if the argument string is equal to this string; a value less than0
if this string is lexicographically less than the string argument; and a value greater than0
if this string is lexicographically greater than the string argument.
compareToIgnoreCase
public int compareToIgnoreCase(String str)
- Compares two strings lexicographically, ignoring case
differences. This method returns an integer whose sign is that of
calling
compareTo
with normalized versions of the strings where case differences have been eliminated by callingCharacter.toLowerCase(Character.toUpperCase(character))
on each character.Note that this method does not take locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package provides collators to allow locale-sensitive ordering.
- Parameters:
str
- theString
to be compared.- Returns:
- a negative integer, zero, or a positive integer as the specified String is greater than, equal to, or less than this String, ignoring case considerations.
- Since:
- 1.2
- See Also:
Collator.compare(String, String)
regionMatches
public boolean regionMatches(int toffset, String other, int ooffset, int len)
- Tests if two string regions are equal.
A substring of this String object is compared to a substring of the argument other. The result is true if these substrings represent identical character sequences. The substring of this String object to be compared begins at index toffset and has length len. The substring of other to be compared begins at index ooffset and has length len. The result is false if and only if at least one of the following is true:
- toffset is negative.
- ooffset is negative.
- toffset+len is greater than the length of this String object.
- ooffset+len is greater than the length of the other argument.
- There is some nonnegative integer k less than len such that: this.charAt(toffset+k) != other.charAt(ooffset+k)
- Parameters:
toffset
- the starting offset of the subregion in this string.other
- the string argument.ooffset
- the starting offset of the subregion in the string argument.len
- the number of characters to compare.- Returns:
true
if the specified subregion of this string exactly matches the specified subregion of the string argument;false
otherwise.
regionMatches
public boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len)
- Tests if two string regions are equal.
A substring of this String object is compared to a substring of the argument other. The result is true if these substrings represent character sequences that are the same, ignoring case if and only if ignoreCase is true. The substring of this String object to be compared begins at index toffset and has length len. The substring of other to be compared begins at index ooffset and has length len. The result is false if and only if at least one of the following is true:
- toffset is negative.
- ooffset is negative.
- toffset+len is greater than the length of this String object.
- ooffset+len is greater than the length of the other argument.
- ignoreCase is false and there is some nonnegative
integer k less than len such that:
this.charAt(toffset+k) != other.charAt(ooffset+k)
- ignoreCase is true and there is some nonnegative
integer k less than len such that:
and:Character.toLowerCase(this.charAt(toffset+k)) != Character.toLowerCase(other.charAt(ooffset+k))
Character.toUpperCase(this.charAt(toffset+k)) != Character.toUpperCase(other.charAt(ooffset+k))
- Parameters:
ignoreCase
- iftrue
, ignore case when comparing characters.toffset
- the starting offset of the subregion in this string.other
- the string argument.ooffset
- the starting offset of the subregion in the string argument.len
- the number of characters to compare.- Returns:
true
if the specified subregion of this string matches the specified subregion of the string argument;false
otherwise. Whether the matching is exact or case insensitive depends on theignoreCase
argument.
startsWith
public boolean startsWith(String prefix, int toffset)
- Tests if this string starts with the specified prefix beginning
at the specified index.
- Parameters:
prefix
- the prefix.toffset
- where to begin looking in the string.- Returns:
true
if the character sequence represented by the argument is a prefix of the substring of this object starting at indextoffset
;false
otherwise. The result isfalse
iftoffset
is negative or greater than the length of thisString
object; otherwise the result is the same as the result of the expressionthis.substring(toffset).startsWith(prefix)
startsWith
public boolean startsWith(String prefix)
- Tests if this string starts with the specified prefix.
- Parameters:
prefix
- the prefix.- Returns:
true
if the character sequence represented by the argument is a prefix of the character sequence represented by this string;false
otherwise. Note also thattrue
will be returned if the argument is an empty string or is equal to thisString
object as determined by theequals(Object)
method.- Since:
- 1. 0
endsWith
public boolean endsWith(String suffix)
- Tests if this string ends with the specified suffix.
- Parameters:
suffix
- the suffix.- Returns:
true
if the character sequence represented by the argument is a suffix of the character sequence represented by this object;false
otherwise. Note that the result will betrue
if the argument is the empty string or is equal to thisString
object as determined by theequals(Object)
method.
hashCode
public int hashCode()
- Returns a hash code for this string. The hash code for a
String
object is computed as
usings[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
int
arithmetic, wheres[i]
is the ith character of the string,n
is the length of the string, and^
indicates exponentiation. (The hash value of the empty string is zero.)- Returns:
- a hash code value for this object.
- See Also:
Object.equals(java.lang.Object)
,Hashtable
indexOf
public int indexOf(int ch)
- Returns the index within this string of the first occurrence of
the specified character. If a character with value
ch
occurs in the character sequence represented by thisString
object, then the index (in Unicode code units) of the first such occurrence is returned. For values ofch
in the range from 0 to 0xFFFF (inclusive), this is the smallest value k such that:
is true. For other values ofthis.charAt(k) == ch
ch
, it is the smallest value k such that:
is true. In either case, if no such character occurs in this string, thenthis.codePointAt(k) == ch
-1
is returned.- Parameters:
ch
- a character (Unicode code point).- Returns:
- the index of the first occurrence of the character in the
character sequence represented by this object, or
-1
if the character does not occur.
indexOf
public int indexOf(int ch, int fromIndex)
- Returns the index within this string of the first occurrence of the
specified character, starting the search at the specified index.
If a character with value
ch
occurs in the character sequence represented by thisString
object at an index no smaller thanfromIndex
, then the index of the first such occurrence is returned. For values ofch
in the range from 0 to 0xFFFF (inclusive), this is the smallest value k such that:
is true. For other values of(this.charAt(k) == ch) && (k >= fromIndex)
ch
, it is the smallest value k such that:
is true. In either case, if no such character occurs in this string at or after position(this.codePointAt(k) == ch) && (k >= fromIndex)
fromIndex
, then-1
is returned.There is no restriction on the value of
fromIndex
. If it is negative, it has the same effect as if it were zero: this entire string may be searched. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string:-1
is returned.All indices are specified in
char
values (Unicode code units).- Parameters:
ch
- a character (Unicode code point).fromIndex
- the index to start the search from.- Returns:
- the index of the first occurrence of the character in the
character sequence represented by this object that is greater
than or equal to
fromIndex
, or-1
if the character does not occur.
lastIndexOf
public int lastIndexOf(int ch)
- Returns the index within this string of the last occurrence of
the specified character. For values of
ch
in the range from 0 to 0xFFFF (inclusive), the index (in Unicode code units) returned is the largest value k such that:
is true. For other values ofthis.charAt(k) == ch
ch
, it is the largest value k such that:
is true. In either case, if no such character occurs in this string, thenthis.codePointAt(k) == ch
-1
is returned. TheString
is searched backwards starting at the last character.- Parameters:
ch
- a character (Unicode code point).- Returns:
- the index of the last occurrence of the character in the
character sequence represented by this object, or
-1
if the character does not occur.
lastIndexOf
public int lastIndexOf(int ch, int fromIndex)
- Returns the index within this string of the last occurrence of
the specified character, searching backward starting at the
specified index. For values of
ch
in the range from 0 to 0xFFFF (inclusive), the index returned is the largest value k such that:
is true. For other values of(this.charAt(k) == ch) && (k <= fromIndex)
ch
, it is the largest value k such that:
is true. In either case, if no such character occurs in this string at or before position(this.codePointAt(k) == ch) && (k <= fromIndex)
fromIndex
, then-1
is returned.All indices are specified in
char
values (Unicode code units).- Parameters:
ch
- a character (Unicode code point).fromIndex
- the index to start the search from. There is no restriction on the value offromIndex
. 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.- Returns:
- the index of the last occurrence of the character in the
character sequence represented by this object that is less
than or equal to
fromIndex
, or-1
if the character does not occur before that point.
indexOf
public int indexOf(String str)
- Returns the index within this string of the first occurrence of the
specified substring. The integer returned is the smallest value
k such that:
isthis.startsWith(str, k)
true
.- Parameters:
str
- any string.- Returns:
- 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,
-1
is returned.
indexOf
public int indexOf(String str, int fromIndex)
- 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 k for which:
If no such value of k exists, then -1 is returned.k >= Math.min(fromIndex, str.length()) && this.startsWith(str, k)
- Parameters:
str
- the substring for which to search.fromIndex
- the index from which to start the search.- Returns:
- the index within this string of the first occurrence of the specified substring, starting at the specified index.
lastIndexOf
public int lastIndexOf(String str)
- 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
this.length()
. The returned index is the largest value k such that
is true.this.startsWith(str, k)
- Parameters:
str
- the substring to search for.- Returns:
- 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,
-1
is returned.
lastIndexOf
public int lastIndexOf(String str, int fromIndex)
- 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 k such that:
If no such value of k exists, then -1 is returned.k <= Math.min(fromIndex, str.length()) && this.startsWith(str, k)
- Parameters:
str
- the substring to search for.fromIndex
- the index to start the search from.- Returns:
- the index within this string of the last occurrence of the specified substring.
substring
public String substring(int beginIndex)
- Returns a new string that is a substring of this string. The
substring begins with the character at the specified index and
extends to the end of this string.
Examples:
"unhappy".substring(2) returns "happy" "Harbison".substring(3) returns "bison" "emptiness".substring(9) returns "" (an empty string)
- Parameters:
beginIndex
- the beginning index, inclusive.- Returns:
- the specified substring.
- Throws:
IndexOutOfBoundsException
- ifbeginIndex
is negative or larger than the length of thisString
object.
substring
public String substring(int beginIndex, int endIndex)
- Returns a new string that is a substring of this string. The
substring begins at the specified
beginIndex
and extends to the character at indexendIndex - 1
. Thus the length of the substring isendIndex-beginIndex
.Examples:
"hamburger".substring(4, 8) returns "urge" "smiles".substring(1, 5) returns "mile"
- Parameters:
beginIndex
- the beginning index, inclusive.endIndex
- the ending index, exclusive.- Returns:
- the specified substring.
- Throws:
IndexOutOfBoundsException
- if thebeginIndex
is negative, orendIndex
is larger than the length of thisString
object, orbeginIndex
is larger thanendIndex
.
subSequence
public CharSequence subSequence(int beginIndex, int endIndex)
- Returns a new character sequence that is a subsequence of this sequence.
An invocation of this method of the form
behaves in exactly the same way as the invocationstr.subSequence(begin, end)
This method is defined so that the String class can implement thestr.substring(begin, end)
CharSequence
interface.- Specified by:
subSequence
in interfaceCharSequence
- Parameters:
beginIndex
- the begin index, inclusive.endIndex
- the end index, exclusive.- Returns:
- the specified subsequence.
- Throws:
IndexOutOfBoundsException
- if beginIndex or endIndex are negative, if endIndex is greater than length(), or if beginIndex is greater than startIndex- Since:
- 1.4
concat
public String concat(String str)
- Concatenates the specified string to the end of this string.
If the length of the argument string is
0
, then thisString
object is returned. Otherwise, a newString
object is created, representing a character sequence that is the concatenation of the character sequence represented by thisString
object and the character sequence represented by the argument string.Examples:
"cares".concat("s") returns "caress" "to".concat("get").concat("her") returns "together"
- Parameters:
str
- theString
that is concatenated to the end of thisString
.- Returns:
- a string that represents the concatenation of this object's characters followed by the string argument's characters.
replace
public String replace(char oldChar, char newChar)
- Returns a new string resulting from replacing all occurrences of
oldChar
in this string withnewChar
.If the character
oldChar
does not occur in the character sequence represented by thisString
object, then a reference to thisString
object is returned. Otherwise, a newString
object is created that represents a character sequence identical to the character sequence represented by thisString
object, except that every occurrence ofoldChar
is replaced by an occurrence ofnewChar
.Examples:
"mesquite in your cellar".replace('e', 'o') returns "mosquito in your collar" "the war of baronets".replace('r', 'y') returns "the way of bayonets" "sparring with a purple porpoise".replace('p', 't') returns "starring with a turtle tortoise" "JonL".replace('q', 'x') returns "JonL" (no change)
- Parameters:
oldChar
- the old character.newChar
- the new character.- Returns:
- a string derived from this string by replacing every
occurrence of
oldChar
withnewChar
.
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)- 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
- Throws:
PatternSyntaxException
- if the regular expression's syntax is invalid- 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 - Throws:
NullPointerException
- ifs
isnull
- 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)- Parameters:
regex
- the regular expression to which this string is to be matched- Returns:
- The resulting String
- Throws:
PatternSyntaxException
- if the regular expression's syntax is invalid- 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)- Parameters:
regex
- the regular expression to which this string is to be matched- Returns:
- The resulting String
- Throws:
PatternSyntaxException
- if the regular expression's syntax is invalid- 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 replacedreplacement
- The replacement sequence of char values- Returns:
- The resulting string
- Throws:
NullPointerException
- iftarget
orreplacement
isnull
.- 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.
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)- Parameters:
regex
- the delimiting regular expressionlimit
- the result threshold, as described above- Returns:
- 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- 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" } - Parameters:
regex
- the delimiting regular expression- Returns:
- 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- Since:
- 1.4
- See Also:
Pattern
toLowerCase
public String toLowerCase(Locale locale)
- Converts all of the characters in this
String
to lower case using the rules of the givenLocale
. Case mapping is based on the Unicode Standard version specified by theCharacter
class. Since case mappings are not always 1:1 char mappings, the resultingString
may be a different length than the originalString
.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()
- Converts all of the characters in this
String
to lower case using the rules of the default locale. This is equivalent to callingtoLowerCase(Locale.getDefault())
.- Returns:
- the
String
, converted to lowercase. - See Also:
toLowerCase(Locale)
toUpperCase
public String toUpperCase(Locale locale)
- Converts all of the characters in this
String
to upper case using the rules of the givenLocale
. Case mapping is based on the Unicode Standard version specified by theCharacter
class. Since case mappings are not always 1:1 char mappings, the resultingString
may be a different length than the originalString
.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()
- Converts all of the characters in this
String
to upper case using the rules of the default locale. This method is equivalent totoUpperCase(Locale.getDefault())
.- Returns:
- the
String
, converted to uppercase. - See Also:
toUpperCase(Locale)
trim
public String trim()
- Returns a copy of the string, with leading and trailing whitespace
omitted.
If this
String
object represents an empty character sequence, or the first and last characters of character sequence represented by thisString
object both have codes greater than'\u0020'
(the space character), then a reference to thisString
object is returned.Otherwise, if there is no character with a code greater than
'\u0020'
in the string, then a newString
object representing an empty string is created and returned.Otherwise, let k be the index of the first character in the string whose code is greater than
'\u0020'
, and let m be the index of the last character in the string whose code is greater than'\u0020'
. A newString
object is created, representing the substring of this string that begins with the character at index k and ends with the character at index m-that is, the result ofthis.substring(k, m+1)
.This method may be used to trim whitespace (as defined above) from the beginning and end of a string.
- Returns:
- A copy of this string with leading and trailing white space removed, or this string if it has no leading or trailing white space.
toString
public String toString()
- This object (which is already a string!) is itself returned.
- Specified by:
toString
in interfaceCharSequence
- Overrides:
toString
in classObject
- Returns:
- the string itself.
toCharArray
public char[] toCharArray()
- Converts this string to a new character array.
- Returns:
- 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.
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()
.- Parameters:
format
- A format stringargs
- 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
- 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- 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.
- Parameters:
l
- The locale to apply during formatting. If l is null then no localization is applied.format
- A format stringargs
- 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
- 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 specificationNullPointerException
- If the format is null- Since:
- 1.5
- See Also:
Formatter
valueOf
public static String valueOf(Object obj)
- Returns the string representation of the
Object
argument.- Parameters:
obj
- anObject
.- Returns:
- if the argument is
null
, then a string equal to"null"
; otherwise, the value ofobj.toString()
is returned. - See Also:
Object.toString()
valueOf
public static String valueOf(char[] data)
- Returns the string representation of the
char
array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.- Parameters:
data
- achar
array.- Returns:
- a newly allocated string representing the same sequence of characters contained in the character array argument.
valueOf
public static String valueOf(char[] data, int offset, int count)
- Returns the string representation of a specific subarray of the
char
array argument.The
offset
argument is the index of the first character of the subarray. Thecount
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.- Parameters:
data
- the character array.offset
- the initial offset into the value of theString
.count
- the length of the value of theString
.- Returns:
- a string representing the sequence of characters contained in the subarray of the character array argument.
- Throws:
IndexOutOfBoundsException
- ifoffset
is negative, orcount
is negative, oroffset+count
is larger thandata.length
.
copyValueOf
public static String copyValueOf(char[] data, int offset, int count)
- Returns a String that represents the character sequence in the
array specified.
- Parameters:
data
- the character array.offset
- initial offset of the subarray.count
- length of the subarray.- Returns:
- a
String
that contains the characters of the specified subarray of the character array.
copyValueOf
public static String copyValueOf(char[] data)
- Returns a String that represents the character sequence in the
array specified.
- Parameters:
data
- the character array.- Returns:
- a
String
that contains the characters of the character array.
valueOf
public static String valueOf(boolean b)
- Returns the string representation of the
boolean
argument.- Parameters:
b
- aboolean
.- Returns:
- if the argument is
true
, a string equal to"true"
is returned; otherwise, a string equal to"false"
is returned.
valueOf
public static String valueOf(char c)
- Returns the string representation of the
char
argument.- Parameters:
c
- achar
.- Returns:
- a string of length
1
containing as its single character the argumentc
.
valueOf
public static String valueOf(int i)
- Returns the string representation of the
int
argument.The representation is exactly the one returned by the
Integer.toString
method of one argument.- Parameters:
i
- anint
.- Returns:
- a string representation of the
int
argument. - See Also:
Integer.toString(int, int)
valueOf
public static String valueOf(long l)
- Returns the string representation of the
long
argument.The representation is exactly the one returned by the
Long.toString
method of one argument.- Parameters:
l
- along
.- Returns:
- a string representation of the
long
argument. - See Also:
Long.toString(long)
valueOf
public static String valueOf(float f)
- Returns the string representation of the
float
argument.The representation is exactly the one returned by the
Float.toString
method of one argument.- Parameters:
f
- afloat
.- Returns:
- a string representation of the
float
argument. - See Also:
Float.toString(float)
valueOf
public static String valueOf(double d)
- Returns the string representation of the
double
argument.The representation is exactly the one returned by the
Double.toString
method of one argument.- Parameters:
d
- adouble
.- Returns:
- a string representation of the
double
argument. - See Also:
Double.toString(double)
intern
public String intern()
- Returns a canonical representation for the string object.
A pool of strings, initially empty, is maintained privately by the class
String
.When the intern method is invoked, if the pool already contains a string equal to this
String
object as determined by theequals(Object)
method, then the string from the pool is returned. Otherwise, thisString
object is added to the pool and a reference to thisString
object is returned.It follows that for any two strings
s
andt
,s.intern() == t.intern()
istrue
if and only ifs.equals(t)
istrue
.All literal strings and string-valued constant expressions are interned. String literals are defined in §3.10.5 of the Java Language Specification
- Returns:
- a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.
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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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