public final class String extends Object implements Comparable<String>, CharSequence
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).
Object.toString()
,
StringBuffer
,
StringBuilder
Constructor and Description |
---|
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[] bytes,
int offset,
int length)
Constructs a new
String by decoding the specified subarray of
bytes using the platform's default charset. |
String(byte[] bytes,
int offset,
int length,
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 subarray 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(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.
|
Modifier and Type | Method and Description |
---|---|
char |
charAt(int index)
Returns the
char value at the
specified index. |
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)
Compares this string to the specified
CharSequence . |
boolean |
contentEquals(StringBuffer sb)
Compares this string to 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(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. |
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.
|
boolean |
isEmpty()
|
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 last 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 |
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 the substring of this string beginning at the
specified index starts with the specified prefix.
|
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 |
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 |
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. |
public String()
String
object so that it represents
an empty character sequence. Note that use of this constructor is
unnecessary since Strings are immutable.public String(byte[] bytes)
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.
bytes
- The bytes to be decoded into characterspublic String(byte[] bytes, int offset, int length)
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.
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
arraypublic String(byte[] bytes, int offset, int length, String charsetName) throws UnsupportedEncodingException
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.
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 charsetUnsupportedEncodingException
- If the named charset is not supportedIndexOutOfBoundsException
- If the offset
and length
arguments index
characters outside the bounds of the bytes
arraypublic String(byte[] bytes, String charsetName) throws UnsupportedEncodingException
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.
bytes
- The bytes to be decoded into characterscharsetName
- The name of a supported charsetUnsupportedEncodingException
- If the named charset is not supportedpublic 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 stringpublic 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 charactersoffset
- The initial offsetcount
- The lengthIndexOutOfBoundsException
- If the offset
and count
arguments index
characters outside the bounds of the value
arraypublic 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. Unless an
explicit copy of original
is needed, use of this constructor is
unnecessary since Strings are immutable.original
- A String
public String(StringBuffer buffer)
buffer
- A StringBuffer
public String(StringBuilder builder)
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 StringBuilder
public char charAt(int index)
char
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.
charAt
in interface CharSequence
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.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()
compareTo
in interface Comparable<String>
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.public int compareToIgnoreCase(String str)
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.
str
- the String
to be compared.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
.public boolean contains(CharSequence s)
s
- the sequence to search fors
, false otherwisepublic boolean contentEquals(CharSequence cs)
CharSequence
. The
result is true
if and only if this String
represents the
same sequence of char values as the specified sequence. Note that if the
CharSequence
is a StringBuffer
then the method
synchronizes on it.cs
- The sequence to compare this String
againsttrue
if this String
represents the same
sequence of char values as the specified sequence, false
otherwisepublic boolean contentEquals(StringBuffer sb)
StringBuffer
. The result
is true
if and only if this String
represents the same
sequence of characters as the specified StringBuffer
. This method
synchronizes on the StringBuffer
.sb
- The StringBuffer
to compare this String
againsttrue
if this String
represents the same
sequence of characters as the specified StringBuffer
,
false
otherwisepublic static String copyValueOf(char[] data)
data
- the character array.String
that contains the characters of the
character array.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 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.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
againsttrue
if the given object represents a String
equivalent to this string, false
otherwisecompareTo(String)
,
equalsIgnoreCase(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
againsttrue
if the argument is not null
and it
represents an equivalent String
ignoring case; false
otherwiseequals(Object)
public static String format(String format, Object... args)
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.IllegalArgumentException
- 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.Formatter
public byte[] getBytes()
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.
public byte[] getBytes(String charsetName) throws UnsupportedEncodingException
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.
charsetName
- The name of a supported charsetUnsupportedEncodingException
- If the named charset is not supportedpublic 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
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
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public int indexOf(int ch)
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.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. 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.public int indexOf(String str)
The returned index is the smallest value k for which:
If no such value of k exists, thenthis.startsWith(str, k)
-1
is returned.str
- the substring to search for.-1
if there is no such occurrence.public int indexOf(String str, int fromIndex)
The returned index is the smallest value k for which:
k >= Math.min(fromIndex, this.length()) &&
this.toString().startsWith(str, k)
If no such value of k exists, then -1
is returned.str
- the substring to search for.fromIndex
- the index from which to start the search.-1
if there is no such occurrence.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 section 3.10.5 of the The Java™ Language Specification.
public boolean isEmpty()
true
if length()
is 0
, otherwise
false
public int lastIndexOf(int ch)
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.public int lastIndexOf(int ch, int fromIndex)
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.public int lastIndexOf(String str)
this.length()
.
The returned index is the largest value k for which:
If no such value of k exists, thenthis.startsWith(str, k)
-1
is returned.str
- the substring to search for.-1
if there is no such occurrence.public int lastIndexOf(String str, int fromIndex)
The returned index is the largest value k for which:
k <= Math.min(fromIndex, this.length()) &&
this.toString().startsWith(str, k)
If no such value of k exists, then -1
is returned.str
- the substring to search for.fromIndex
- the index to start the search from.-1
if there is no such occurrence.public int length()
length
in interface CharSequence
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:
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))
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 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
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.
len
such that:
this.charAt(toffset +
k) != other.charAt(ooffset +
k)
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.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 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.public boolean startsWith(String prefix, int toffset)
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)
public CharSequence subSequence(int beginIndex, int 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 thestr.substring(begin, end)
String
class can implement
the CharSequence
interface.subSequence
in interface CharSequence
beginIndex
- the begin index, inclusive.endIndex
- the end index, exclusive.IndexOutOfBoundsException
- if beginIndex
or endIndex
is negative,
if endIndex
is greater than length()
,
or if beginIndex
is greater than endIndex
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 char[] toCharArray()
public String toLowerCase()
String
to lower
case using the rules of the default locale.
This method is equivalent to applying Character.toLowerCase()
to all characters in the String.
Note that by default CLDC only supports the ISO Latin-1 range of characters.
String
, converted to lowercase.public String toString()
toString
in interface CharSequence
toString
in class Object
public String toUpperCase()
String
to upper
case using the rules of the default locale.
This method is equivalent to applying Character.toUpperCase()
to all characters in the String.
Note that by default CLDC only supports the ISO Latin-1 range of characters.
String
, converted to uppercase.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 (as defined above) from the beginning and end of a string.
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(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
.IndexOutOfBoundsException
- if offset
is
negative, or count
is negative, or
offset+count
is larger than
data.length
.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 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(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(Object obj)
Object
argument.obj
- an Object
.null
, then a string equal to
"null"
; otherwise, the value of
obj.toString()
is returned.Object.toString()
Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. Use of this specification is subject to license terms.