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
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).
Object.toString()StringBufferStringBuilderjava.nio.charset.Charset
TC_STRING (utf String)
The String is written by method DataOutput.writeUTF.
A new handle is generated to refer to all future references to the
string instance within the stream.
String object so that it represents
the same sequence of characters as the argument; in other words, the
newly created string is a copy of the argument string. Unless an
explicit copy of original is needed, use of this constructor is
unnecessary since Strings are immutable.
original
A StringString 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 stringString 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 charactersoffset
The initial offsetcount
The lengthIndexOutOfBoundsException
If the offset and count arguments index
characters outside the bounds of the value arrayString that contains characters from a subarray
of the Unicode code point array
argument. The offset argument is the index of the first code
point of the subarray and the count argument specifies the
length of the subarray. The contents of the subarray are converted to
chars; subsequent modification of the int array does not
affect the newly created string.
codePoints
Array that is the source of Unicode code pointsoffset
The initial offsetcount
The lengthIllegalArgumentException
If any invalid Unicode code point is found in codePointsIndexOutOfBoundsException
If the offset and count arguments index
characters outside the bounds of the codePoints arrayString 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.
String constructors that take a java.nio.charset.Charsetascii
The bytes to be converted to charactershibyte
The top 8 bits of each 16-bit Unicode code unitoffset
The initial offsetcount
The lengthIndexOutOfBoundsException
If the offset or count argument is invalidString(byte[],int) String(byte[],int,int,java.lang.String) String(byte[],int,int,java.nio.charset.Charset) String(byte[],int,int) String(byte[],java.lang.String) String(byte[],java.nio.charset.Charset) String(byte[]) String 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))
String constructors that take a java.nio.charset.Charsetascii
The bytes to be converted to charactershibyte
The top 8 bits of each 16-bit Unicode code unitString(byte[],int,int,java.lang.String) String(byte[],int,int,java.nio.charset.Charset) String(byte[],int,int) String(byte[],java.lang.String) String(byte[],java.nio.charset.Charset) String(byte[]) String 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 java.nio.charset.CharsetDecoder
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 supported charsetjava.io.UnsupportedEncodingException
If the named charset is not supportedIndexOutOfBoundsException
If the offset and length arguments index
characters outside the bounds of the bytes arrayString by decoding the specified subarray of
bytes using the specified charset.
The length of the new String is a function of the charset, and
hence may not be equal to the length of the subarray.
This method always replaces malformed-input and unmappable-character
sequences with this charset's default replacement string. The java.nio.charset.CharsetDecoder
bytes
The bytes to be decoded into charactersoffset
The index of the first byte to decodelength
The number of bytes to decodecharset
The charset to be used to
decode the bytesIndexOutOfBoundsException
If the offset and length arguments index
characters outside the bounds of the bytes arrayString 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 java.nio.charset.CharsetDecoder
bytes
The bytes to be decoded into characterscharsetName
The name of a supported charsetjava.io.UnsupportedEncodingException
If the named charset is not supportedString by decoding the specified array of
bytes using the specified charset.
The length of the new String is a function of the charset, and
hence may not be equal to the length of the byte array.
This method always replaces malformed-input and unmappable-character
sequences with this charset's default replacement string. The java.nio.charset.CharsetDecoder
bytes
The bytes to be decoded into characterscharset
The charset to be used to
decode the bytesString 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 java.nio.charset.CharsetDecoder
bytes
The bytes to be decoded into charactersoffset
The index of the first byte to decodelength
The number of bytes to decodeIndexOutOfBoundsException
If the offset and the length arguments index
characters outside the bounds of the bytes arrayString 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 java.nio.charset.CharsetDecoder
bytes
The bytes to be decoded into characters This constructor is provided to ease migration to StringBuilder. Obtaining a string from a string builder via the toString method is likely to run faster and is generally preferred.
builder
A StringBuilderchar value at the
specified index. An index ranges from 0 to
length() - 1. The first char value of the sequence
is at index 0, the next at index 1,
and so on, as for array indexing.
If the char value specified by the index is a
surrogate, the surrogate
value is returned.
index the index of the char value.char value at the specified index of this string.
The first char value is at index 0.IndexOutOfBoundsException if the index
argument is negative or not less than the length of this
string.char values
(Unicode code units) and ranges from 0 to
length() - 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 this String, and the
char value at the following index is in the
low-surrogate range, then the supplementary code point
corresponding to this surrogate pair is returned. Otherwise,
the char value at the given index is returned.
index the index to the char valuesindexIndexOutOfBoundsException if the index
argument is negative or not less than the length of this
string.char values
(Unicode code units) and ranges from 1 to CharSequence.length() If the char value at (index - 1)
is in the low-surrogate range, (index - 2) is not
negative, and the char value at (index -
2) is in the high-surrogate range, then the
supplementary code point value of the surrogate pair is
returned. If the char value at index -
1 is an unpaired low-surrogate or a high-surrogate, the
surrogate value is returned.
index the index following the code point that should be returnedIndexOutOfBoundsException if the index
argument is less than 1 or greater than the length
of this string.String. The text range begins at the
specified beginIndex and extends to the
char at index endIndex - 1. Thus the
length (in chars) of the text range is
endIndex-beginIndex. Unpaired surrogates within
the text range count as one code point each.
beginIndex the index to the first char of
the text range.endIndex the index after the last char of
the text range.IndexOutOfBoundsException if the
beginIndex is negative, or endIndex
is larger than the length of this String, or
beginIndex is larger than endIndex.String that is
offset from the given index by
codePointOffset code points. Unpaired surrogates
within the text range given by index and
codePointOffset count as one code point each.
index the index to be offsetcodePointOffset the offset in code pointsStringIndexOutOfBoundsException if index
is negative or larger then the length of this
String, or if codePointOffset is positive
and the substring starting with index has fewer
than codePointOffset code points,
or if codePointOffset is negative and the substring
before index has fewer than the absolute value
of codePointOffset code points.
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 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
getBytes()srcBegin
Index of the first character in the string to copysrcEnd
Index after the last character in the string to copydst
The destination arraydstBegin
The start offset in the destination arrayIndexOutOfBoundsException
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
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 java.nio.charset.CharsetEncoder
charsetName
The name of a supported charsetjava.io.UnsupportedEncodingException
If the named charset is not supportedString into a sequence of bytes using the given
charset, storing the result into a
new byte array.
This method always replaces malformed-input and unmappable-character
sequences with this charset's default replacement byte array. The
java.nio.charset.CharsetEncoder
charset
The java.nio.charset.Charset to be used to encode
the StringString 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 java.nio.charset.CharsetEncoder
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.
anObject
The object to compare this String againsttrue if the given object represents a String
equivalent to this string, false otherwisecompareTo(java.lang.String)equalsIgnoreCase(java.lang.String)StringBuffer. The result
is true if and only if this String represents the same
sequence of characters as the specified StringBuffer.
sb
The StringBuffer to compare this String againsttrue if this String represents the same
sequence of characters as the specified StringBuffer,
false otherwiseCharSequence. The result
is true if and only if this String represents the same
sequence of char values as the specified sequence.
cs
The sequence to compare this String againsttrue if this String represents the same
sequence of char values as the specified sequence, false otherwiseString 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)Character.toLowerCase(char)anotherString
The String to compare this String againsttrue if the argument is not null and it
represents an equivalent String ignoring case; false otherwiseequals(java.lang.Object)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(java.lang.Object)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.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.
java.text.Collator.compare(java.lang.String,java.lang.String)compareTo with normalized versions of the strings
where case differences have been eliminated by calling
Character.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.
str the String to be compared.java.text.Collator.compare(java.lang.String,java.lang.String)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.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.prefix the prefix.toffset where to begin looking in this 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)
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(java.lang.Object)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(java.lang.Object)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.)
ch occurs in the character sequence represented by
this String object, then the index (in Unicode
code units) of the first such occurrence is returned. For
values of ch 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.
ch a character (Unicode code point).-1 if the character does not occur.
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. For values
of ch 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).
ch a character (Unicode code point).fromIndex the index to start the search from.fromIndex, or -1
if the character does not occur.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. The
String is searched backwards starting at the last
character.
ch a character (Unicode code point).-1 if the character does not occur.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).
ch a character (Unicode code point).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.isthis.startsWith(str, k)
true.
str any string.-1 is returned.
k >= Math.min(fromIndex, this.length()) && this.startsWith(str, k)
str the substring for which to search.fromIndex the index from which to start the search.source the characters being searched.sourceOffset offset of the source string.sourceCount count of the source string.target the characters being searched for.targetOffset offset of the target string.targetCount count of the target string.fromIndex the index to begin searching from.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.
k <= Math.min(fromIndex, this.length()) && this.startsWith(str, k)
str the substring to search for.fromIndex the index to start the search from.source the characters being searched.sourceOffset offset of the source string.sourceCount count of the source string.target the characters being searched for.targetOffset offset of the target string.targetCount count of the target string.fromIndex the index to begin searching from.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.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.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)
CharSequencebeginIndex the begin index, inclusive.endIndex the end index, exclusive.IndexOutOfBoundsException
if beginIndex or endIndex are negative,
if endIndex is greater than length(),
or if beginIndex is greater than startIndex
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.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.An invocation of this method of the form str.matches(regex) yields exactly the same result as the expression
.java.util.regex.Pattern(regex, str)java.util.regex.Pattern.matches(java.lang.String,java.lang.CharSequence)
regex
the regular expression to which this string is to be matchedjava.util.regex.PatternSyntaxException
if the regular expression's syntax is invalidjava.util.regex.Patterns the sequence to search fors, false otherwiseNullPointerException if s is nullAn invocation of this method of the form str.replaceFirst(regex, repl) yields exactly the same result as the expression
.java.util.regex.Patterncompile(regex).(str).java.util.regex.Pattern.matcher(java.lang.CharSequence)replaceFirst(repl)
Note that backslashes (\) and dollar signs ($) in the
replacement string may cause the results to be different than if it were
being treated as a literal replacement string; see
java.util.regex.Matcherjava.util.regex.Matcher
regex
the regular expression to which this string is to be matchedreplacement
the string to be substituted for the first matchjava.util.regex.PatternSyntaxException
if the regular expression's syntax is invalidjava.util.regex.PatternAn invocation of this method of the form str.replaceAll(regex, repl) yields exactly the same result as the expression
.java.util.regex.Patterncompile(regex).(str).java.util.regex.Pattern.matcher(java.lang.CharSequence)replaceAll(repl)
Note that backslashes (\) and dollar signs ($) in the
replacement string may cause the results to be different than if it were
being treated as a literal replacement string; see
Matcher.replaceAll.
Use java.util.regex.Matcher
regex
the regular expression to which this string is to be matchedreplacement
the string to be substituted for each matchjava.util.regex.PatternSyntaxException
if the regular expression's syntax is invalidjava.util.regex.Patterntarget The sequence of char values to be replacedreplacement The replacement sequence of char valuesNullPointerException if target or
replacement is null.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
.java.util.regex.Patterncompile(regex).(str, n)java.util.regex.Pattern.split(java.lang.CharSequence,int)
regex
the delimiting regular expressionlimit
the result threshold, as described abovejava.util.regex.PatternSyntaxException
if the regular expression's syntax is invalidjava.util.regex.Pattern This method works as if by invoking the two-argument split(java.lang.String,int)
The string "boo:and:foo", for example, yields the following results with these expressions:
Regex Result : { "boo", "and", "foo" } o { "b", "", ":and:f" }
regex
the delimiting regular expressionjava.util.regex.PatternSyntaxException
if the regular expression's syntax is invalidjava.util.regex.PatternString to lower
case using the rules of the given Locale. Case mapping is based
on the Unicode Standard version specified by the Character
class. Since case mappings are not always 1:1 char mappings, the resulting
String may be a different length than the original String.
Examples of lowercase mappings are in the following table:
| Language Code of Locale | Upper Case | Lower Case | Description |
|---|---|---|---|
| tr (Turkish) | \u0130 | \u0069 | capital letter I with dot above -> small letter i |
| tr (Turkish) | \u0049 | \u0131 | capital letter I -> small letter dotless i |
| (all) | French Fries | french fries | lowercased all chars in String |
| (all) | lowercased all chars in String |
locale use the case transformation rules for this localeString, converted to lowercase.toLowerCase()toUpperCase()toUpperCase(java.util.Locale)String to lower
case using the rules of the default locale. This is equivalent to calling
toLowerCase(Locale.getDefault()).
Note: This method is locale sensitive, and may produce unexpected
results if used for strings that are intended to be interpreted locale
independently.
Examples are programming language identifiers, protocol keys, and HTML
tags.
For instance, "TITLE".toLowerCase() in a Turkish locale
returns "t\u0131tle", where '\u0131' is the LATIN SMALL
LETTER DOTLESS I character.
To obtain correct results for locale insensitive strings, use
toLowerCase(Locale.ENGLISH).
String, converted to lowercase.toLowerCase(java.util.Locale)String to upper
case using the rules of the given Locale. Case mapping is based
on the Unicode Standard version specified by the Character
class. Since case mappings are not always 1:1 char mappings, the resulting
String may be a different length than the original String.
Examples of locale-sensitive and 1:M case mappings are in the following table.
| Language Code of Locale | Lower Case | Upper Case | Description |
|---|---|---|---|
| tr (Turkish) | \u0069 | \u0130 | small letter i -> capital letter I with dot above |
| tr (Turkish) | \u0131 | \u0049 | small letter dotless i -> capital letter I |
| (all) | \u00df | \u0053 \u0053 | small letter sharp s -> two letters: SS |
| (all) | Fahrvergnügen | FAHRVERGNÜGEN |
locale use the case transformation rules for this localeString, converted to uppercase.toUpperCase()toLowerCase()toLowerCase(java.util.Locale)String to upper
case using the rules of the default locale. This method is equivalent to
toUpperCase(Locale.getDefault()).
Note: This method is locale sensitive, and may produce unexpected
results if used for strings that are intended to be interpreted locale
independently.
Examples are programming language identifiers, protocol keys, and HTML
tags.
For instance, "title".toUpperCase() in a Turkish locale
returns "T\u0130TLE", where '\u0130' is the LATIN CAPITAL
LETTER I WITH DOT ABOVE character.
To obtain correct results for locale insensitive strings, use
toUpperCase(Locale.ENGLISH).
String, converted to uppercase.toUpperCase(java.util.Locale)
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 (as defined above) from the beginning and end of a string.
The locale always used is the one returned by java.util.Locale.getDefault()
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.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 nulljava.util.Formatterl
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.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 nulljava.util.FormatterObject argument.
obj an Object.null, then a string equal to
"null"; otherwise, the value of
obj.toString() is returned.Object.toString()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.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.IndexOutOfBoundsException if offset is
negative, or count is negative, or
offset+count is larger than
data.length.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)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)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)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)
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(java.lang.Object)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