|
JavaTM 2 Platform Std. Ed. v1.3.1 |
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--java.lang.String
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.
The Java language provides special support for the string
concatentation operator ( + ), and for conversion of
other objects to strings. String concatenation is implemented
through the 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.
Object.toString()
,
StringBuffer
,
StringBuffer.append(boolean)
,
StringBuffer.append(char)
,
StringBuffer.append(char[])
,
StringBuffer.append(char[], int, int)
,
StringBuffer.append(double)
,
StringBuffer.append(float)
,
StringBuffer.append(int)
,
StringBuffer.append(long)
,
StringBuffer.append(java.lang.Object)
,
StringBuffer.append(java.lang.String)
,
Character encodings, Serialized FormField Summary | |
static Comparator |
CASE_INSENSITIVE_ORDER
Returns 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)
Construct a new String by converting the specified array
of bytes using the platform's default character encoding. |
|
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 character-encoding name or
that use the platform's default encoding. |
|
String(byte[] bytes,
int offset,
int length)
Construct a new String by converting the specified
subarray of bytes using the platform's default character encoding. |
|
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 character-encoding name or
that use the platform's default encoding. |
|
String(byte[] bytes,
int offset,
int length,
String enc)
Construct a new String by converting the specified
subarray of bytes using the specified character encoding. |
|
String(byte[] bytes,
String enc)
Construct a new String by converting the specified array
of bytes using the specified character encoding. |
|
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(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. |
Method Summary | |
char |
charAt(int index)
Returns the character at the specified index. |
int |
compareTo(Object o)
Compares this String to another Object. |
int |
compareTo(String anotherString)
Compares two strings lexicographically. |
int |
compareToIgnoreCase(String str)
Compares two strings lexicographically, ignoring case considerations. |
String |
concat(String str)
Concatenates the specified string to the end of this string. |
static String |
copyValueOf(char[] data)
Returns a String that is equivalent to the specified character array. |
static String |
copyValueOf(char[] data,
int offset,
int count)
Returns a String that is equivalent to the specified character array. |
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. |
byte[] |
getBytes()
Convert this String into bytes according to the platform's
default character encoding, 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(String enc) method, which takes a
character-encoding name, or the getBytes() method, which
uses the platform's default encoding. |
byte[] |
getBytes(String enc)
Convert this String into bytes according to the specified
character encoding, 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 hashcode 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. |
int |
length()
Returns the length of this string. |
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 . |
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. |
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, which is returned
by Locale.getDefault . |
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, which is returned
by Locale.getDefault . |
String |
toUpperCase(Locale locale)
Converts all of the characters in this String to upper
case using the rules of the given locale. |
String |
trim()
Removes white space from both ends of this string. |
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 |
public static final Comparator CASE_INSENSITIVE_ORDER
String
objects as by
compareToIgnoreCase
. This comparator is serializable.
Note that this Comparator does not take locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package provides Collators to allow locale-sensitive ordering.
Collator.compare(String, String)
Constructor Detail |
public String()
String
object so that it
represents an empty character sequence.public String(String original)
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.value
- a String
.public String(char[] value)
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.value
- the initial value of the string.NullPointerException
- if value
is null
.public String(char[] value, int offset, int count)
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.value
- array that is the source of characters.offset
- the initial offset.count
- the length.IndexOutOfBoundsException
- if the offset
and count
arguments index characters outside
the bounds of the value
array.NullPointerException
- if value
is
null
.public String(byte[] ascii, int hibyte, int offset, int count)
String
constructors that take a character-encoding name or
that use the platform's default encoding.
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.
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.IndexOutOfBoundsException
- if the offset
or count
argument is invalid.NullPointerException
- if ascii
is
null
.String(byte[], int)
,
String(byte[], int, int, java.lang.String)
,
String(byte[], int, int)
,
String(byte[], java.lang.String)
,
String(byte[])
public String(byte[] ascii, int hibyte)
String
constructors that take a character-encoding name or
that use the platform's default encoding.
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))
ascii
- the bytes to be converted to characters.hibyte
- the top 8 bits of each 16-bit Unicode character.NullPointerException
- If ascii
is
null
.String(byte[], int, int, java.lang.String)
,
String(byte[], int, int)
,
String(byte[], java.lang.String)
,
String(byte[])
public String(byte[] bytes, int offset, int length, String enc) throws UnsupportedEncodingException
String
by converting the specified
subarray of bytes using the specified character encoding. The length of
the new String
is a function of the encoding, and hence may
not be equal to the length of the subarray.bytes
- The bytes to be converted into charactersoffset
- Index of the first byte to convertlength
- Number of bytes to convertenc
- The name of a supported
character
encodingUnsupportedEncodingException
- if the named encoding is not supportedIndexOutOfBoundsException
- if the offset
and count
arguments
index characters outside the bounds of the value
array.public String(byte[] bytes, String enc) throws UnsupportedEncodingException
String
by converting the specified array
of bytes using the specified character encoding. The length of the new
String
is a function of the encoding, and hence may not be
equal to the length of the byte array.bytes
- The bytes to be converted into charactersenc
- The name of a supported
character
encodingUnsupportedEncodingException
- If the named encoding is not supportedpublic String(byte[] bytes, int offset, int length)
String
by converting the specified
subarray of bytes using the platform's default character encoding. The
length of the new String
is a function of the encoding, and
hence may not be equal to the length of the subarray.bytes
- The bytes to be converted into charactersoffset
- Index of the first byte to convertlength
- Number of bytes to convertpublic String(byte[] bytes)
String
by converting the specified array
of bytes using the platform's default character encoding. The length of
the new String
is a function of the encoding, and hence may
not be equal to the length of the byte array.bytes
- The bytes to be converted into characterspublic String(StringBuffer buffer)
buffer
- a StringBuffer
.NullPointerException
- If buffer
is
null
.Method Detail |
public int length()
public char charAt(int index)
0
to length() - 1
. The first character
of the sequence is at index 0
, the next at index
1
, and so on, as for array indexing.index
- the index of the character.0
.IndexOutOfBoundsException
- if the index
argument is negative or not less than the length of this
string.public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
The first character to be copied is at index srcBegin
;
the last character to be copied is at index srcEnd-1
(thus the total number of characters to be copied is
srcEnd-srcBegin
). The characters are copied into the
subarray of dst
starting at index dstBegin
and ending at index:
dstbegin + (srcEnd-srcBegin) - 1
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.IndexOutOfBoundsException
- If any of the following
is true:
srcBegin
is negative.
srcBegin
is greater than srcEnd
srcEnd
is greater than the length of this
string
dstBegin
is negative
dstBegin+(srcEnd-srcBegin)
is larger than
dst.length
NullPointerException
- if dst
is null
public void getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin)
getBytes(String enc)
method, which takes a
character-encoding name, or the getBytes()
method, which
uses the platform's default encoding.
The first character to be copied is at index srcBegin
;
the last character to be copied is at index srcEnd-1
.
The total number of characters to be copied is
srcEnd-srcBegin
. The characters, converted to bytes,
are copied into the subarray of dst
starting at index
dstBegin
and ending at index:
dstbegin + (srcEnd-srcBegin) - 1
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.IndexOutOfBoundsException
- if any of the following
is true:
srcBegin
is negative
srcBegin
is greater than srcEnd
srcEnd
is greater than the length of this
String
dstBegin
is negative
dstBegin+(srcEnd-srcBegin)
is larger than
dst.length
NullPointerException
- if dst
is null
public byte[] getBytes(String enc) throws UnsupportedEncodingException
String
into bytes according to the specified
character encoding, storing the result into a new byte array.enc
- The name of a supported
character
encodingUnsupportedEncodingException
- If the named encoding is not supportedpublic byte[] getBytes()
String
into bytes according to the platform's
default character encoding, storing the result into a new byte array.public boolean equals(Object anObject)
true
if and only if the argument is not
null
and is a String
object that represents
the same sequence of characters as this object.equals
in class Object
anObject
- the object to compare this String
against.true
if the String
are equal;
false
otherwise.compareTo(java.lang.String)
,
equalsIgnoreCase(java.lang.String)
public boolean equalsIgnoreCase(String anotherString)
String
to another String
,
ignoring case considerations. Two strings are considered equal
ignoring case if they are of the same length, and corresponding
characters in the two strings are equal ignoring case.
Two characters c1
and c2
are considered
the same, ignoring case if at least one of the following is true:
==
operator).
Character.toUpperCase(char)
to each character produces the same result.
Character.toLowerCase(char)
to each character produces the same result.anotherString
- the String
to compare this
String
against.true
if the argument is not null
and the String
s are equal,
ignoring case; false
otherwise.equals(Object)
,
Character.toLowerCase(char)
,
Character.toUpperCase(char)
public int compareTo(String anotherString)
String
object is compared lexicographically to the
character sequence represented by the argument string. The result is
a negative integer if this String
object
lexicographically precedes the argument string. The result is a
positive integer if this String
object lexicographically
follows the argument string. The result is zero if the strings
are equal; compareTo
returns 0
exactly when
the equals(Object)
method would return true
.
This is the definition of lexicographic ordering. If two strings are
different, then either they have different characters at some index
that is a valid index for both strings, or their lengths are different,
or both. If they have different characters at one or more index
positions, let k be the smallest such index; then the string
whose character at position k has the smaller value, as
determined by using the < operator, lexicographically precedes the
other string. In this case, compareTo
returns the
difference of the two character values at position k
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()
anotherString
- the String
to be compared.0
if the argument string is equal to
this string; a value less than 0
if this string
is lexicographically less than the string argument; and a
value greater than 0
if this string is
lexicographically greater than the string argument.NullPointerException
- if anotherString
is null
.public int compareTo(Object o)
compareTo(String)
. Otherwise,
it throws a ClassCastException
(as Strings are comparable
only to other Strings).compareTo
in interface Comparable
o
- the Object
to be compared.0
if the argument is a string
lexicographically equal to this string; a value less than
0
if the argument is a string lexicographically
greater than this string; and a value greater than
0
if the argument is a string lexicographically
less than this string.ClassCastException
- if the argument is not a
String
.Comparable
public int compareToIgnoreCase(String str)
this.toUpperCase().toLowerCase().compareTo(
str.toUpperCase().toLowerCase())
.
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.
str
- the String
to be compared.Collator.compare(String, String)
public boolean regionMatches(int toffset, String other, int ooffset, int len)
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
- 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.true
if the specified subregion of this string
exactly matches the specified subregion of the string argument;
false
otherwise.NullPointerException
- if other is
null.public boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len)
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:
this.charAt(toffset+k) != other.charAt(ooffset+k)
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))
ignoreCase
- if true
, 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.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 the ignoreCase
argument.public boolean startsWith(String prefix, int toffset)
prefix
- the prefix.toffset
- where to begin looking in the string.true
if the character sequence represented by the
argument is a prefix of the substring of this object starting
at index toffset
; false
otherwise.
The result is false
if toffset
is
negative or greater than the length of this
String
object; otherwise the result is the same
as the result of the expression
this.subString(toffset).startsWith(prefix)
NullPointerException
- if prefix
is
null
.public boolean startsWith(String prefix)
prefix
- the prefix.true
if the character sequence represented by the
argument is a prefix of the character sequence represented by
this string; false
otherwise.
Note also that true
will be returned if the
argument is an empty string or is equal to this
String
object as determined by the
equals(Object)
method.NullPointerException
- if prefix
is
null
.public boolean endsWith(String suffix)
suffix
- the suffix.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 be true
if the argument is the
empty string or is equal to this String
object
as determined by the equals(Object)
method.NullPointerException
- if suffix
is
null
.public int hashCode()
String
object is computed as
usings[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
int
arithmetic, where s[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.)hashCode
in class Object
public int indexOf(int ch)
ch
occurs
in the character sequence represented by this String
object, then the index of the first such occurrence is returned --
that is, the smallest value k such that:
isthis.charAt(k) == ch
true
. If no such character occurs in this string,
then -1
is returned.ch
- a character.-1
if the character does not occur.public int indexOf(int ch, int fromIndex)
If a character with value ch
occurs in the character
sequence represented by this String
object at an index
no smaller than fromIndex
, then the index of the first
such occurrence is returned--that is, the smallest value k
such that:
is true. If no such character occurs in this string at or after position(this.charAt(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.
ch
- a character.fromIndex
- the index to start the search from.fromIndex
, or -1
if the character does not occur.public int lastIndexOf(int ch)
is true. The String is searched backwards starting at the last character.this.charAt(k) == ch
ch
- a character.-1
if the character does not occur.public int lastIndexOf(int ch, int fromIndex)
is true.this.charAt(k) == ch) && (k <= fromIndex)
ch
- a character.fromIndex
- the index to start the search from. There is no
restriction on the value of fromIndex
. If it is
greater than or equal to the length of this string, it has
the same effect as if it were equal to one less than the
length of this string: this entire string may be searched.
If it is negative, it has the same effect as if it were -1:
-1 is returned.fromIndex
, or -1
if the character does not occur before that point.public int indexOf(String str)
isthis.startsWith(str, k)
true
.str
- any string.-1
is returned.NullPointerException
- if str
is
null
.public int indexOf(String str, int fromIndex)
isthis.startsWith(str, k) && (k >= fromIndex)
true
.
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.
str
- the substring to search for.fromIndex
- the index to start the search from.fromIndex
, then the index of the first character
of the first such substring is returned. If it does not occur
as a substring starting at fromIndex
or beyond,
-1
is returned.NullPointerException
- if str
is
null
public int lastIndexOf(String str)
this.length()
.
The returned index is the largest value k such that
is true.this.startsWith(str, k)
str
- the substring to search for.-1
is returned.NullPointerException
- if str
is
null
.public int lastIndexOf(String str, int fromIndex)
fromIndex
. That is,
the index returned is the largest value k such that:
this.startsWith(str, k) && (k <= fromIndex)
str
- the substring to search for.fromIndex
- the index to start the search from. There is no
restriction on the value of fromIndex. 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: this entire string
may be searched. If it is negative, it has the same effect
as if it were -1: -1 is returned.fromIndex
, then the index of the first character of
the last such substring is returned. If it does not occur as a
substring starting at fromIndex
or earlier,
-1
is returned.NullPointerException
- if str
is
null
.public String substring(int beginIndex)
Examples:
"unhappy".substring(2) returns "happy" "Harbison".substring(3) returns "bison" "emptiness".substring(9) returns "" (an empty string)
beginIndex
- the beginning index, inclusive.IndexOutOfBoundsException
- if
beginIndex
is negative or larger than the
length of this String
object.public String substring(int beginIndex, int endIndex)
beginIndex
and
extends to the character at index endIndex - 1
.
Thus the length of the substring is endIndex-beginIndex
.
Examples:
"hamburger".substring(4, 8) returns "urge" "smiles".substring(1, 5) returns "mile"
beginIndex
- the beginning index, inclusive.endIndex
- the ending index, exclusive.IndexOutOfBoundsException
- if the
beginIndex
is negative, or
endIndex
is larger than the length of
this String
object, or
beginIndex
is larger than
endIndex
.public String concat(String str)
If the length of the argument string is 0
, then this
String
object is returned. Otherwise, a new
String
object is created, representing a character
sequence that is the concatenation of the character sequence
represented by this String
object and the character
sequence represented by the argument string.
Examples:
"cares".concat("s") returns "caress" "to".concat("get").concat("her") returns "together"
str
- the String
that is concatenated to the end
of this String
.NullPointerException
- if str
is
null
.public String replace(char oldChar, char newChar)
oldChar
in this string with newChar
.
If the character oldChar
does not occur in the
character sequence represented by this String
object,
then a reference to this String
object is returned.
Otherwise, a new String
object is created that
represents a character sequence identical to the character sequence
represented by this String
object, except that every
occurrence of oldChar
is replaced by an occurrence
of newChar
.
Examples:
"mesquite in your cellar".replace('e', 'o') returns "mosquito in your collar" "the war of baronets".replace('r', 'y') returns "the way of bayonets" "sparring with a purple porpoise".replace('p', 't') returns "starring with a turtle tortoise" "JonL".replace('q', 'x') returns "JonL" (no change)
oldChar
- the old character.newChar
- the new character.oldChar
with newChar
.public String toLowerCase(Locale locale)
String
to lower
case using the rules of the given Locale
.
Usually, the characters are converted by calling
Character.toLowerCase
.
Exceptions to this rule are listed 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 |
locale
- use the case transformation rules for this localeCharacter.toLowerCase(char)
,
toUpperCase(Locale)
public String toLowerCase()
String
to lower
case using the rules of the default locale, which is returned
by Locale.getDefault
.
If no character in the string has a different lowercase version,
based on calling the toLowerCase
method defined by
Character
, then the original string is returned.
Otherwise, this method creates a new String
object that
represents a character sequence identical in length to the character
sequence represented by this String object, with every character
equal to the result of applying the method
Character.toLowerCase
to the corresponding character of
this String
object.
Examples:
"French Fries".toLowerCase() returns "french fries" "".toLowerCase() returns ""
Character.toLowerCase(char)
,
toLowerCase(Locale)
public String toUpperCase(Locale locale)
String
to upper
case using the rules of the given locale.
Usually, the characters are converted by calling
Character.toUpperCase
.
Exceptions to this rule are listed 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 |
locale
- use the case transformation rules for this localeCharacter.toUpperCase(char)
,
toLowerCase(Locale)
public String toUpperCase()
String
to upper
case using the rules of the default locale, which is returned
by Locale.getDefault
.
If no character in this string has a different uppercase version,
based on calling the toUpperCase
method defined by
Character
, then the original string is returned.
Otherwise, this method creates a new String
object
representing a character sequence identical in length to the
character sequence represented by this String
object and
with every character equal to the result of applying the method
Character.toUpperCase
to the corresponding character of
this String
object.
Examples:
"Fahrvergnügen".toUpperCase() returns "FAHRVERGNÜGEN" "Visit Ljubinje!".toUpperCase() returns "VISIT LJUBINJE!"
Character.toUpperCase(char)
,
toUpperCase(Locale)
public String trim()
If this String
object represents an empty character
sequence, or the first and last characters of character sequence
represented by this String
object both have codes
greater than '\u0020'
(the space character), then a
reference to this String
object is returned.
Otherwise, if there is no character with a code greater than
'\u0020'
in the string, then a new
String
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 new String
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 of
this.substring(k, m+1)
.
This method may be used to trim
whitespace
from the beginning and end
of a string; in fact, it trims all ASCII control characters as well.
public String toString()
toString
in class Object
public char[] toCharArray()
public static String valueOf(Object obj)
Object
argument.obj
- an Object
.null
, then a string equal to
"null"
; otherwise, the value of
obj.toString()
is returned.Object.toString()
public static String valueOf(char[] data)
char
array
argument. The contents of the character array are copied; subsequent
modification of the character array does not affect the newly
created string.data
- a char
array.public static String valueOf(char[] data, int offset, int count)
char
array argument.
The offset
argument is the index of the first
character of the subarray. 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.
data
- the character array.offset
- the initial offset into the value of the
String
.count
- the length of the value of the String
.NullPointerException
- if data
is
null
.IndexOutOfBoundsException
- if offset
is
negative, or count
is negative, or
offset+count
is larger than
data.length
.public static String copyValueOf(char[] data, int offset, int count)
data
- the character array.offset
- initial offset of the subarray.count
- length of the subarray.String
that contains the characters of the
specified subarray of the character array.public static String copyValueOf(char[] data)
data
- the character array.String
that contains the characters of the
character array.public static String valueOf(boolean b)
boolean
argument.b
- a boolean
.true
, a string equal to
"true"
is returned; otherwise, a string equal to
"false"
is returned.public static String valueOf(char c)
char
argument.c
- a char
.1
containing
as its single character the argument c
.public static String valueOf(int i)
int
argument.
The representation is exactly the one returned by the
Integer.toString
method of one argument.
i
- an int
.int
argument.Integer.toString(int, int)
public static String valueOf(long l)
long
argument.
The representation is exactly the one returned by the
Long.toString
method of one argument.
l
- a long
.long
argument.Long.toString(long)
public static String valueOf(float f)
float
argument.
The representation is exactly the one returned by the
Float.toString
method of one argument.
f
- a float
.float
argument.Float.toString(float)
public static String valueOf(double d)
double
argument.
The representation is exactly the one returned by the
Double.toString
method of one argument.
d
- a double
.double
argument.Double.toString(double)
public String intern()
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
the equals(Object)
method, then the string from the pool is
returned. Otherwise, this String
object is added to the
pool and a reference to this String
object is returned.
It follows that for any two strings s
and t
,
s.intern() == t.intern()
is true
if and only if s.equals(t)
is true
.
All literal strings and string-valued constant expressions are interned. String literals are defined in §3.10.5 of the Java Language Specification
|
JavaTM 2 Platform Std. Ed. v1.3.1 |
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
Java, Java 2D, and JDBC are trademarks or registered trademarks of Oracle and/or its affiliates, in the US and other countries.
Copyright © 1995, 2010 Oracle and/or its affiliates. All rights reserved.