Serializable
, CharSequence
, Comparable<String>
, Constable
, ConstantDesc
The
String
class represents character strings. All string literals in Java programs, such as
"abc"
, are implemented as instances of this class.
Strings are constant; their values cannot be changed after they are created. String buffers support mutable strings. Because String objects are immutable they can be shared. For example:
String str = "abc";
is equivalent to:
char data[] = {'a', 'b', 'c'}; String str = new String(data);
Here are some more examples of how strings can be used:
System.out.println("abc"); String cde = "cde"; System.out.println("abc" + cde); String c = "abc".substring(2, 3); String d = cde.substring(1, 2);
The class String
includes methods for examining individual characters of the sequence, for comparing strings, for searching strings, for extracting substrings, and for creating a copy of a string with all characters translated to uppercase or to lowercase. Case mapping is based on the Unicode Standard version specified by the Character
class.
The Java language provides special support for the string concatenation operator ( + ), and for conversion of other objects to strings. For additional information on string concatenation and conversion, see 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).
Unless otherwise noted, methods for comparing Strings do not take locale into account. The Collator
class provides methods for finer-grain, locale-sensitive String comparison.
javac
compiler may implement the operator with StringBuffer
, StringBuilder
, or java.lang.invoke.StringConcatFactory
depending on the JDK version. The implementation of string conversion is typically through the method toString
, defined by Object
and inherited by all classes in Java.
Fields
Constructors
Initializes a newly created String
object so that it represents an empty character sequence.
Constructs a new
String
by decoding the specified array of bytes using the
default charset
.
String(byte[] ascii, int hibyte)
String(byte[] bytes, int offset, int length)
Constructs a new
String
by decoding the specified subarray of bytes using the
default charset
.
String(byte[] ascii, int hibyte, int offset, int count)
String(byte[] bytes, int offset, int length, String charsetName)
Constructs a new String
by decoding the specified subarray of bytes using the specified charset.
Constructs a new
String
by decoding the specified subarray of bytes using the specified
charset.
Constructs a new
String
by decoding the specified array of bytes using the specified
charset.
Constructs a new
String
by decoding the specified array of bytes using the specified
charset.
Allocates a new String
so that it represents the sequence of characters currently contained in the character array argument.
String(char[] value, int offset, int count)
Allocates a new String
that contains characters from a subarray of the character array argument.
String(int[] codePoints, int offset, int count)
Allocates a new
String
that contains characters from a subarray of the
Unicode code pointarray argument.
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.
Allocates a new string that contains the sequence of characters currently contained in the string buffer argument.
Allocates a new string that contains the sequence of characters currently contained in the string builder argument.
char
Returns the char
value at the specified index.
Returns a stream of int
zero-extending the char
values from this sequence.
int
Returns the character (Unicode code point) at the specified index.
int
Returns the character (Unicode code point) before the specified index.
int
Returns the number of Unicode code points in the specified text range of this String
.
Returns a stream of code point values from this sequence.
int
Compares two strings lexicographically.
int
Compares two strings lexicographically, ignoring case differences.
Concatenates the specified string to the end of this string.
boolean
Returns true if and only if this string contains the specified sequence of char values.
boolean
Compares this string to the specified CharSequence
.
boolean
Compares this string to the specified StringBuffer
.
Returns an
Optional
containing the nominal descriptor for this instance, which is the instance itself.
boolean
Tests if this string ends with the specified suffix.
boolean
Compares this string to the specified object.
boolean
Compares this String
to another String
, ignoring case considerations.
Returns a formatted string using the specified format string and arguments.
Returns a formatted string using the specified locale, format string, and arguments.
Formats using this string as the format string, and the supplied arguments.
byte[]
Encodes this
String
into a sequence of bytes using the
default charset
, storing the result into a new byte array.
void
getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin)
byte[]
Encodes this String
into a sequence of bytes using the named charset, storing the result into a new byte array.
byte[]
Encodes this
String
into a sequence of bytes using the given
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
Returns a hash code for this string.
Adjusts the indentation of each line of this string based on the value of n
, and normalizes line termination characters.
int
Returns the index within this string of the first occurrence of the specified character.
int
Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.
int
indexOf(int ch, int beginIndex, int endIndex)
Returns the index within this string of the first occurrence of the specified character, starting the search at beginIndex
and stopping before endIndex
.
int
Returns the index within this string of the first occurrence of the specified substring.
int
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
int
Returns the index of the first occurrence of the specified substring within the specified index range of this
string.
Returns a canonical representation for the string object.
boolean
Returns
true
if the string is empty or contains only
white spacecodepoints, otherwise
false
.
boolean
Returns
true
if, and only if,
length()
is
0
.
Returns a new String composed of copies of the CharSequence elements
joined together with a copy of the specified delimiter
.
Returns a new String
composed of copies of the CharSequence elements
joined together with a copy of the specified delimiter
.
int
Returns the index within this string of the last occurrence of the specified character.
int
Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index.
int
Returns the index within this string of the last occurrence of the specified substring.
int
Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.
int
Returns the length of this string.
Returns a stream of lines extracted from this string, separated by line terminators.
boolean
int
Returns the index within this String
that is offset from the given index
by codePointOffset
code points.
boolean
Tests if two string regions are equal.
boolean
Tests if two string regions are equal.
Returns a string whose value is the concatenation of this string repeated count
times.
replace(char oldChar, char newChar)
Returns a string resulting from replacing all occurrences of oldChar
in this string with newChar
.
Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.
Replaces each substring of this string that matches the given
regular expressionwith the given replacement.
Replaces the first substring of this string that matches the given
regular expressionwith the given replacement.
Resolves this instance as a
ConstantDesc
, the result of which is the instance itself.
Splits this string around matches of the given regular expression and returns both the strings and the matching delimiters.
boolean
Tests if this string starts with the specified prefix.
boolean
Tests if the substring of this string beginning at the specified index starts with the specified prefix.
Returns a string whose value is this string, with all leading and trailing
white spaceremoved.
Returns a string whose value is this string, with incidental
white spaceremoved from the beginning and end of every line.
Returns a string whose value is this string, with all leading
white spaceremoved.
Returns a string whose value is this string, with all trailing
white spaceremoved.
Returns a character sequence that is a subsequence of this sequence.
Returns a string that is a substring of this string.
Returns a string that is a substring of this string.
char[]
Converts this string to a new character array.
Converts all of the characters in this String
to lower case using the rules of the default locale.
Converts all of the characters in this String
to lower case using the rules of the given Locale
.
This object (which is already a string!)
Converts all of the characters in this String
to upper case using the rules of the default locale.
Converts all of the characters in this String
to upper case using the rules of the given Locale
.
<R> R
This method allows the application of a function to this
string.
Returns a string whose value is this string, with escape sequences translated as if in a string literal.
Returns a string whose value is this string, with all leading and trailing space removed, where space is defined as any character whose codepoint is less than or equal to 'U+0020'
(the space character).
Returns the string representation of the boolean
argument.
Returns the string representation of the char
argument.
Returns the string representation of the char
array argument.
valueOf(char[] data, int offset, int count)
Returns the string representation of a specific subarray of the char
array argument.
Returns the string representation of the double
argument.
Returns the string representation of the float
argument.
Returns the string representation of the int
argument.
Returns the string representation of the long
argument.
Returns the string representation of the Object
argument.
A Comparator that orders
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 Collator
class provides locale-sensitive comparison.
public String()
Initializes a newly created String
object so that it represents an empty character sequence. Note that use of this constructor is unnecessary since Strings are immutable.
Initializes a newly created String
object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string. Unless an explicit copy of original
is needed, use of this constructor is unnecessary since Strings are immutable.
original
- A String
public String(char[] value)
Allocates a new String
so that it represents the sequence of characters currently contained in the character array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.
value
- The initial value of the string
public String(char[] value, int offset, int count)
Allocates a new String
that contains characters from a subarray of the character array argument. The offset
argument is the index of the first character of the subarray and the count
argument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.
value
- Array that is the source of characters
offset
- The initial offset
count
- The length
IndexOutOfBoundsException
- If offset
is negative, count
is negative, or offset
is greater than value.length - count
public String(int[] codePoints, int offset, int count)
Allocates a new
String
that contains characters from a subarray of the
Unicode code pointarray 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
char
s; subsequent modification of the
int
array does not affect the newly created string.
codePoints
- Array that is the source of Unicode code points
offset
- The initial offset
count
- The length
IllegalArgumentException
- If any invalid Unicode code point is found in codePoints
IndexOutOfBoundsException
- If offset
is negative, count
is negative, or offset
is greater than codePoints.length - count
Allocates a new
String
constructed from a subarray of an array of 8-bit integer values.
The offset
argument is the index of the first byte of the subarray, and the count
argument specifies the length of the subarray.
Each byte
in the subarray is converted to a char
as specified in the String(byte[],int)
constructor.
ascii
- The bytes to be converted to characters
hibyte
- The top 8 bits of each 16-bit Unicode code unit
offset
- The initial offset
count
- The length
IndexOutOfBoundsException
- If offset
is negative, count
is negative, or offset
is greater than ascii.length - count
Allocates a new
String
containing characters constructed from an array of 8-bit integer values. Each character
cin the resulting string is constructed from the corresponding component
bin 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 code unit
Constructs a new
String
by decoding the specified subarray of bytes using the specified charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the subarray.
The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. The CharsetDecoder
class should be used when more control over the decoding process is required.
bytes
- The bytes to be decoded into characters
offset
- The index of the first byte to decode
length
- The number of bytes to decode
charsetName
- The name of a supported charset
UnsupportedEncodingException
- If the named charset is not supported
IndexOutOfBoundsException
- If offset
is negative, length
is negative, or offset
is greater than bytes.length - length
Constructs a new
String
by decoding the specified subarray of bytes using the specified
charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the subarray.
This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. The CharsetDecoder
class should be used when more control over the decoding process is required.
bytes
- The bytes to be decoded into characters
offset
- The index of the first byte to decode
length
- The number of bytes to decode
charset
- The charset to be used to decode the bytes
IndexOutOfBoundsException
- If offset
is negative, length
is negative, or offset
is greater than bytes.length - length
Constructs a new
String
by decoding the specified array of bytes using the specified
charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the byte array.
The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. The CharsetDecoder
class should be used when more control over the decoding process is required.
bytes
- The bytes to be decoded into characters
charsetName
- The name of a supported charset
UnsupportedEncodingException
- If the named charset is not supported
Constructs a new
String
by decoding the specified array of bytes using the specified
charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the byte array.
This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement string. The CharsetDecoder
class should be used when more control over the decoding process is required.
bytes
- The bytes to be decoded into characters
charset
- The charset to be used to decode the bytes
public String(byte[] bytes, int offset, int length)
Constructs a new
String
by decoding the specified subarray of bytes using the
default charset
. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the subarray.
The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The CharsetDecoder
class should be used when more control over the decoding process is required.
bytes
- The bytes to be decoded into characters
offset
- The index of the first byte to decode
length
- The number of bytes to decode
IndexOutOfBoundsException
- If offset
is negative, length
is negative, or offset
is greater than bytes.length - length
public String(byte[] bytes)
Constructs a new
String
by decoding the specified array of bytes using the
default charset
. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the byte array.
The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The CharsetDecoder
class should be used when more control over the decoding process is required.
bytes
- The bytes to be decoded into characters
Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. The contents of the string buffer are copied; subsequent modification of the string buffer does not affect the newly created string.
buffer
- A StringBuffer
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 int length()
Returns the length of this string. The length is equal to the number of
Unicode code unitsin the string.
length
in interface CharSequence
public boolean isEmpty()
Returns
true
if, and only if,
length()
is
0
.
isEmpty
in interface CharSequence
true
if length()
is 0
, otherwise false
public char charAt(int index)
Returns the
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 codePointAt(int index)
Returns the character (Unicode code point) at the specified index. The index refers to
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
values
index
IndexOutOfBoundsException
- if the index
argument is negative or not less than the length of this string.
public int codePointBefore(int index)
Returns the character (Unicode code point) before the specified index. The index refers to
char
values (Unicode code units) and ranges from
1
to
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 returned
IndexOutOfBoundsException
- if the index
argument is less than 1 or greater than the length of this string.
public int codePointCount(int beginIndex, int endIndex)
Returns the number of Unicode code points in the specified text range of this String
. The text range begins at the specified beginIndex
and extends to the char
at index endIndex - 1
. Thus the length (in char
s) 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
.
public int offsetByCodePoints(int index, int codePointOffset)
Returns the index within this 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 offset
codePointOffset
- the offset in code points
String
IndexOutOfBoundsException
- if index
is negative or larger than 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.
public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
Copies characters from this string into the destination character array.
The first character to be copied is at index srcBegin
; the last character to be copied is at 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 stringdstBegin
is negativedstBegin+(srcEnd-srcBegin)
is larger than dst.length
Copies characters from this string into the destination byte array. Each byte receives the 8 low-order bits of the corresponding character. The eight high-order bits of each character are not copied and do not participate in the transfer in any way.
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 negativesrcBegin
is greater than srcEnd
srcEnd
is greater than the length of this StringdstBegin
is negativedstBegin+(srcEnd-srcBegin)
is larger than dst.length
Encodes this
String
into a sequence of bytes using the named charset, storing the result into a new byte array.
The behavior of this method when this string cannot be encoded in the given charset is unspecified. The CharsetEncoder
class should be used when more control over the encoding process is required.
charsetName
- The name of a supported charset
UnsupportedEncodingException
- If the named charset is not supported
Encodes this
String
into a sequence of bytes using the given
charset, storing the result into a new byte array.
This method always replaces malformed-input and unmappable-character sequences with this charset's default replacement byte array. The CharsetEncoder
class should be used when more control over the encoding process is required.
charset
- The Charset to be used to encode the String
public byte[] getBytes()
Encodes this
String
into a sequence of bytes using the
default charset
, storing the result into a new byte array.
The behavior of this method when this string cannot be encoded in the default charset is unspecified. The CharsetEncoder
class should be used when more control over the encoding process is required.
Compares this string to the specified object. The result is
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.
For finer-grained String comparison, refer to Collator
.
Compares this string to the specified
StringBuffer
. The result is
true
if and only if this
String
represents the same sequence of characters as the specified
StringBuffer
. This method synchronizes on the
StringBuffer
.
For finer-grained String comparison, refer to Collator
.
sb
- The StringBuffer
to compare this String
against
true
if this String
represents the same sequence of characters as the specified StringBuffer
, false
otherwise
Compares this string to the specified
CharSequence
. The result is
true
if and only if this
String
represents the same sequence of char values as the specified sequence. Note that if the
CharSequence
is a
StringBuffer
then the method synchronizes on it.
For finer-grained String comparison, refer to Collator
.
cs
- The sequence to compare this String
against
true
if this String
represents the same sequence of char values as the specified sequence, false
otherwise
Compares this
String
to another
String
, ignoring case considerations. Two strings are considered equal ignoring case if they are of the same length and corresponding Unicode code points in the two strings are equal ignoring case.
Two Unicode code points are considered the same ignoring case if at least one of the following is true:
==
operator)Character.toLowerCase(Character.toUpperCase(int))
on each Unicode code point produces the same resultNote that this method does not take locale into account, and will result in unsatisfactory results for certain locales. The Collator
class provides locale-sensitive comparison.
anotherString
- The String
to compare this String
against
true
if the argument is not null
and it represents an equivalent String
ignoring case; false
otherwise
Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. The character sequence represented by this
String
object is compared lexicographically to the character sequence represented by the argument string. The result is a negative integer if 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:
this.charAt(k)-anotherString.charAt(k)
If there is no index position at which they differ, then the shorter string lexicographically precedes the longer string. In this case,
compareTo
returns the difference of the lengths of the strings -- that is, the value:
this.length()-anotherString.length()
For finer-grained String comparison, refer to Collator
.
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.
Compares two strings lexicographically, ignoring case differences. This method returns an integer whose sign is that of calling
compareTo
with case folded versions of the strings where case differences have been eliminated by calling
Character.toLowerCase(Character.toUpperCase(int))
on each Unicode code point.
Note that this method does not take locale into account, and will result in an unsatisfactory ordering for certain locales. The Collator
class provides locale-sensitive comparison.
str
- the String
to be compared.
Tests if two string regions are equal.
A substring of this String
object is compared to a substring of the argument other. The result is true if these substrings represent identical character sequences. The substring of this String
object to be compared begins at index toffset
and has length len
. The substring of other to be compared begins at index ooffset
and has length len
. The result is false
if and only if at least one of the following is true:
toffset
is negative.ooffset
is negative.toffset+len
is greater than the length of this String
object.ooffset+len
is greater than the length of the other argument.len
such that: this.charAt(toffset +
k) != other.charAt(ooffset +
k)
Note that this method does not take locale into account. The Collator
class provides locale-sensitive comparison.
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.
Tests if two string regions are equal.
A substring of this String
object is compared to a substring of the argument other
. The result is true
if these substrings represent Unicode code point sequences that are the same, ignoring case if and only if ignoreCase
is true. The sequences tsequence
and osequence
are compared, where tsequence
is the sequence produced as if by calling this.substring(toffset, toffset + len).codePoints()
and osequence
is the sequence produced as if by calling other.substring(ooffset, ooffset + len).codePoints()
. The result is true
if and only if all of the following are true:
toffset
is non-negative.ooffset
is non-negative.toffset+len
is less than or equal to the length of this String
object.ooffset+len
is less than or equal to the length of the other argument.ignoreCase
is false
, all pairs of corresponding Unicode code points are equal integer values; or if ignoreCase
is true
, Character.toLowerCase(
Character.toUpperCase(int)
)
on all pairs of Unicode code points results in equal integer values.Note that this method does not take locale into account, and will result in unsatisfactory results for certain locales when ignoreCase
is true
. The Collator
class provides locale-sensitive comparison.
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 (Unicode code units - 16bit char
value) 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.
Tests if the substring of this string beginning at the specified index starts with the specified prefix.
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)
Tests if this string starts with the specified 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.
Tests if this string ends with the specified 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 int hashCode()
Returns a hash code for this string. The hash code for a
String
object is computed as
s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
using
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.)
public int indexOf(int ch)
Returns the index within this string of the first occurrence of the specified character. If a character with value
ch
occurs in the character sequence represented by 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
ksuch that:
this.charAt(k) == ch
is true. For other values of
ch
, it is the smallest value
ksuch that:
this.codePointAt(k) == ch
is true. In either case, if no such character occurs in this string, then
-1
is returned.
ch
- a character (Unicode code point).
-1
if the character does not occur.
public int indexOf(int ch, int fromIndex)
Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.
If a character with value ch
occurs in the character sequence represented by 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:
(this.charAt(k) == ch)&&
(k >= fromIndex)
is true. For other values of
ch
, it is the smallest value
ksuch that:
(this.codePointAt(k) == ch)&&
(k >= fromIndex)
is true. In either case, if no such character occurs in this string at or after position
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).
substring(int)
, for example, this method does not throw an exception when fromIndex
is outside the valid range. Rather, it returns -1 when fromIndex
is larger than the length of the string. This result is, by itself, indistinguishable from a genuine absence of ch
in the string. If stricter behavior is needed, indexOf(int, int, int)
should be considered instead. On a String
s
, for example, s.indexOf(ch, fromIndex, s.length())
would throw if fromIndex
were larger than the string length, or were negative.
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(int ch, int beginIndex, int endIndex)
Returns the index within this string of the first occurrence of the specified character, starting the search at
beginIndex
and stopping before
endIndex
.
If a character with value ch
occurs in the character sequence represented by this String
object at an index no smaller than beginIndex
but smaller than endIndex
, 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:
(this.charAt(k) == ch) && (beginIndex <= k < endIndex)
is true. For other values of
ch
, it is the smallest value
ksuch that:
(this.codePointAt(k) == ch) && (beginIndex <= k < endIndex)
is true. In either case, if no such character occurs in this string at or after position
beginIndex
and before position
endIndex
, then
-1
is returned.
All indices are specified in char
values (Unicode code units).
ch
- a character (Unicode code point).
beginIndex
- the index to start the search from (included).
endIndex
- the index to stop the search at (excluded).
beginIndex
and less than endIndex
, or -1
if the character does not occur.
StringIndexOutOfBoundsException
- if beginIndex
is negative, or endIndex
is larger than the length of this String
object, or beginIndex
is larger than endIndex
.
public int lastIndexOf(int ch)
Returns the index within this string of the last occurrence of the specified character. For values of
ch
in the range from 0 to 0xFFFF (inclusive), the index (in Unicode code units) returned is the largest value
ksuch that:
this.charAt(k) == ch
is true. For other values of
ch
, it is the largest value
ksuch that:
this.codePointAt(k) == ch
is true. In either case, if no such character occurs in this string, then
-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)
Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. For values of
ch
in the range from 0 to 0xFFFF (inclusive), the index returned is the largest value
ksuch that:
(this.charAt(k) == ch)&&
(k <= fromIndex)
is true. For other values of
ch
, it is the largest value
ksuch that:
(this.codePointAt(k) == ch)&&
(k <= fromIndex)
is true. In either case, if no such character occurs in this string at or before position
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.
Returns the index within this string of the first occurrence of the specified substring.
The returned index is the smallest value k
for which:
this.startsWith(str, k)
If no such value of
k
exists, then
-1
is returned.
str
- the substring to search for.
-1
if there is no such occurrence.
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
The returned index is the smallest value k
for which:
k >= Math.min(fromIndex, this.length()) &&
this.startsWith(str, k)
If no such value of
k
exists, then
-1
is returned.
substring(int)
, for example, this method does not throw an exception when fromIndex
is outside the valid range. Rather, it returns -1 when fromIndex
is larger than the length of the string. This result is, by itself, indistinguishable from a genuine absence of str
in the string. If stricter behavior is needed, indexOf(String, int, int)
should be considered instead. On String
s
and a non-empty str
, for example, s.indexOf(str, fromIndex, s.length())
would throw if fromIndex
were larger than the string length, or were negative.
str
- the substring to search for.
fromIndex
- the index from which to start the search.
-1
if there is no such occurrence.
Returns the index of the first occurrence of the specified substring within the specified index range of
this
string.
This method returns the same result as the one of the invocation
s.substring(beginIndex, endIndex).indexOf(str) + beginIndex
if the index returned by
indexOf(String)
is non-negative, and returns -1 otherwise. (No substring is instantiated, though.)
str
- the substring to search for.
beginIndex
- the index to start the search from (included).
endIndex
- the index to stop the search at (excluded).
-1
if there is no such occurrence.
StringIndexOutOfBoundsException
- if beginIndex
is negative, or endIndex
is larger than the length of this String
object, or beginIndex
is larger than endIndex
.
Returns the index within this string of the last occurrence of the specified substring. The last occurrence of the empty string "" is considered to occur at the index value
this.length()
.
The returned index is the largest value k
for which:
this.startsWith(str, k)
If no such value of
k
exists, then
-1
is returned.
str
- the substring to search for.
-1
if there is no such occurrence.
Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.
The returned index is the largest value k
for which:
k <= Math.min(fromIndex, this.length()) &&
this.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.
Returns a string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string.
Examples:
"unhappy".substring(2) returns "happy" "Harbison".substring(3) returns "bison" "emptiness".substring(9) returns "" (an empty string)
beginIndex
- the beginning index, inclusive.
IndexOutOfBoundsException
- if beginIndex
is negative or larger than the length of this String
object.
Returns a string that is a substring of this string. The substring begins at the specified
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
.
Returns a character sequence that is a subsequence of this sequence.
An invocation of this method of the form
str.subSequence(begin, end)
behaves in exactly the same way as the invocation
str.substring(begin, end)
subSequence
in interface CharSequence
String
class can implement the CharSequence
interface.
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
Concatenates the specified string to the end of this string.
If the length of the argument string is 0
, then this String
object is returned. Otherwise, a String
object is returned that represents 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
.
Returns a string resulting from replacing all occurrences of
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 String
object is returned 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
.
regex
- the regular expression to which this string is to be matched
true
if, and only if, this string matches the given regular expression
PatternSyntaxException
- if the regular expression's syntax is invalid
Returns true if and only if this string contains the specified sequence of char values.
s
- the sequence to search for
s
, false otherwise
regex
- the regular expression to which this string is to be matched
replacement
- the string to be substituted for the first match
String
PatternSyntaxException
- if the regular expression's syntax is invalid
Replaces each substring of this string that matches the given
regular expressionwith the given replacement.
An invocation of this method of the form str.replaceAll(
regex,
repl)
yields exactly the same result as the expression
Pattern
.compile
(regex).matcher
(str).replaceAll
(repl)
Note that backslashes (\
) and dollar signs ($
) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; see Matcher.replaceAll
. Use Matcher.quoteReplacement(java.lang.String)
to suppress the special meaning of these characters, if desired.
regex
- the regular expression to which this string is to be matched
replacement
- the string to be substituted for each match
String
PatternSyntaxException
- if the regular expression's syntax is invalid
Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence. The replacement proceeds from the beginning of the string to the end, for example, replacing "aa" with "b" in the string "aaa" will result in "ba" rather than "ab".
target
- The sequence of char values to be replaced
replacement
- The replacement sequence of char values
Splits this string around matches of the given
regular expression.
The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string. The substrings in the array are in the order in which they occur in this string. If the expression does not match any part of the input then the resulting array has just one element, namely this string.
When there is a positive-width match at the beginning of this string then an empty leading substring is included at the beginning of the resulting array. A zero-width match at the beginning however never produces such empty leading substring.
The limit
parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array.
If the limit is positive then the pattern will be applied at most limit - 1 times, the array's length will be no greater than limit, and the array's last entry will contain all input beyond the last matched delimiter.
If the limit 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.
If the limit is negative then the pattern will be applied as many times as possible and the array can have any length.
The string "boo:and:foo"
, for example, yields the following results with these parameters:
Split example showing regex, limit, and result Regex Limit Result : 2{ "boo", "and:foo" }
5{ "boo", "and", "foo" }
-2{ "boo", "and", "foo" }
o 5{ "b", "", ":and:f", "", "" }
-2{ "b", "", ":and:f", "", "" }
0{ "b", "", ":and:f" }
An invocation of this method of the form str.split(
regex,
n)
yields the same result as the expression
Pattern
.compile
(regex).split
(str, n)
regex
- the delimiting regular expression
limit
- the result threshold, as described above
PatternSyntaxException
- if the regular expression's syntax is invalid
Splits this string around matches of the given regular expression and returns both the strings and the matching delimiters.
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. Each substring is immediately followed by the subsequence (the delimiter) that matches the given expression, except for the last substring, which is not followed by anything. The substrings in the array and the delimiters are in the order in which they occur in the input. If the expression does not match any part of the input then the resulting array has just one element, namely this string.
When there is a positive-width match at the beginning of this string then an empty leading substring is included at the beginning of the resulting array. A zero-width match at the beginning however never produces such empty leading substring nor the empty delimiter.
The limit
parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array.
The input "boo:::and::foo"
, for example, yields the following results with these parameters:
{ "boo", ":::", "and::foo" }
5 { "boo", ":::", "and", "::", "foo" }
-1 { "boo", ":::", "and", "::", "foo" }
o 5 { "b", "o", "", "o", ":::and::f", "o", "", "o", "" }
-1 { "b", "o", "", "o", ":::and::f", "o", "", "o", "" }
0 { "b", "o", "", "o", ":::and::f", "o", "", "o" }
splitWithDelimiters(
regex,
n)
yields the same result as the expression
Pattern
.compile
(regex).splitWithDelimiters
(str, n)
regex
- the delimiting regular expression
limit
- the result threshold, as described above
Splits this string around matches of the given
regular expression.
This method works as if by invoking the two-argument split
method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array.
The string "boo:and:foo"
, for example, yields the following results with these expressions:
Split examples showing regex and result Regex Result :{ "boo", "and", "foo" }
o{ "b", "", ":and:f" }
regex
- the delimiting regular expression
PatternSyntaxException
- if the regular expression's syntax is invalid
Returns a new String composed of copies of the
CharSequence elements
joined together with a copy of the specified
delimiter
.
For example,String message = String.join("-", "Java", "is", "cool"); // message returned is: "Java-is-cool"
Note that if an element is null, then
"null"
is added.
delimiter
- the delimiter that separates each element
elements
- the elements to join together.
String
that is composed of the elements
separated by the delimiter
NullPointerException
- If delimiter
or elements
is null
Returns a new
String
composed of copies of the
CharSequence elements
joined together with a copy of the specified
delimiter
.
For example,List<String> strings = List.of("Java", "is", "cool"); String message = String.join(" ", strings); // message returned is: "Java is cool" Set<String> strings = new LinkedHashSet<>(List.of("Java", "is", "very", "cool")); String message = String.join("-", strings); // message returned is: "Java-is-very-cool"
Note that if an individual element is
null
, then
"null"
is added.
delimiter
- a sequence of characters that is used to separate each of the elements
in the resulting String
elements
- an Iterable
that will have its elements
joined together.
String
that is composed from the elements
argument
NullPointerException
- If delimiter
or elements
is null
Converts all of the characters in this
String
to lower case using the rules of the given
Locale
. Case mapping is based on the Unicode Standard version specified by the
Character
class. Since case mappings are not always 1:1 char mappings, the resulting
String
and this
String
may differ in length.
Examples of lowercase mappings are in the following table:
Lowercase mapping examples showing language code of locale, upper case, lower case, and description 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) ΙΧΘΥΣ ιχθυσ lowercased all chars in Stringlocale
- use the case transformation rules for this locale
String
, converted to lowercase.
Converts all of the characters in this String
to lower case using the rules of the default locale. This method is equivalent to toLowerCase(Locale.getDefault())
.
"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.ROOT)
.
String
, converted to lowercase.
Converts all of the characters in this
String
to upper case using the rules of the given
Locale
. Case mapping is based on the Unicode Standard version specified by the
Character
class. Since case mappings are not always 1:1 char mappings, the resulting
String
and this
String
may differ in length.
Examples of locale-sensitive and 1:M case mappings are in the following table:
Examples of locale-sensitive and 1:M case mappings. Shows Language code of locale, lower case, upper case, and description. 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 FAHRVERGNÜGENlocale
- use the case transformation rules for this locale
String
, converted to uppercase.
Converts all of the characters in this String
to upper case using the rules of the default locale. This method is equivalent to toUpperCase(Locale.getDefault())
.
"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.ROOT)
.
String
, converted to uppercase.
Returns a string whose value is this string, with all leading and trailing space removed, where space is defined as any character whose codepoint is less than or equal to
'U+0020'
(the space character).
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 that are not space (as defined above), then a reference to this String
object is returned.
Otherwise, if all characters in this string are space (as defined above), then a String
object representing an empty string is returned.
Otherwise, let k be the index of the first character in the string whose code is not a space (as defined above) and let m be the index of the last character in the string whose code is not a space (as defined above). A String
object is returned, 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 space (as defined above) from the beginning and end of a string.
Returns a string whose value is this string, with all leading and trailing
white spaceremoved.
If this String
object represents an empty string, or if all code points in this string are white space, then an empty string is returned.
Otherwise, returns a substring of this string beginning with the first code point that is not a white space up to and including the last code point that is not a white space.
This method may be used to strip white space from the beginning and end of a string.
Returns a string whose value is this string, with all leading
white spaceremoved.
If this String
object represents an empty string, or if all code points in this string are white space, then an empty string is returned.
Otherwise, returns a substring of this string beginning with the first code point that is not a white space up to and including the last code point of this string.
This method may be used to trim white space from the beginning of a string.
()
Returns a string whose value is this string, with all trailing
white spaceremoved.
If this String
object represents an empty string, or if all characters in this string are white space, then an empty string is returned.
Otherwise, returns a substring of this string beginning with the first code point of this string up to and including the last code point that is not a white space.
This method may be used to trim white space from the end of a string.
public boolean isBlank()
Returns
true
if the string is empty or contains only
white spacecodepoints, otherwise
false
.
true
if the string is empty or contains only white space codepoints, otherwise false
Returns a stream of lines extracted from this string, separated by line terminators.
A line terminator is one of the following: a line feed character "\n"
(U+000A), a carriage return character "\r"
(U+000D), or a carriage return followed immediately by a line feed "\r\n"
(U+000D U+000A).
A line is either a sequence of zero or more characters followed by a line terminator, or it is a sequence of one or more characters followed by the end of the string. A line does not include the line terminator.
The stream returned by this method contains the lines from this string in the order in which they occur.
Adjusts the indentation of each line of this string based on the value of
n
, and normalizes line termination characters.
This string is conceptually separated into lines using lines()
. Each line is then adjusted as described below and then suffixed with a line feed "\n"
(U+000A). The resulting lines are then concatenated and returned.
If n > 0
then n
spaces (U+0020) are inserted at the beginning of each line.
If n < 0
then up to n
white space characters are removed from the beginning of each line. If a given line does not contain sufficient white space then all leading white space characters are removed. Each white space character is treated as a single character. In particular, the tab character "\t"
(U+0009) is considered a single character; it is not expanded.
If n == 0
then the line remains unchanged. However, line terminators are still normalized.
n
- number of leading white space characters to add or remove
Returns a string whose value is this string, with incidental
white spaceremoved from the beginning and end of every line.
Incidental white space is often present in a text block to align the content with the opening delimiter. For example, in the following code, dots represent incidental white space:
String html = """ ..............<html> .............. <body> .............. <p>Hello, world</p> .............. </body> ..............</html> ..............""";
This method treats the incidental
white spaceas indentation to be stripped, producing a string that preserves the relative indentation of the content. Using | to visualize the start of each line of the string:
|<html> | <body> | <p>Hello, world</p> | </body> |</html>
First, the individual lines of this string are extracted. A
lineis a sequence of zero or more characters followed by either a line terminator or the end of the string. If the string has at least one line terminator, the last line consists of the characters between the last terminator and the end of the string. Otherwise, if the string has no terminators, the last line is the start of the string to the end of the string, in other words, the entire string. A line does not include the line terminator.
Then, the minimum indentation (min) is determined as follows:
For each non-blank line (as defined by isBlank()
), the leading white space characters are counted.
The leading white space characters on the last line are also counted even if blank.
The min value is the smallest of these counts.
For each non-blank line, min leading white space characters are removed, and any trailing white space characters are removed. Blank lines are replaced with the empty string.
Finally, the lines are joined into a new string, using the LF character "\n"
(U+000A) to separate lines.
()
Returns a string whose value is this string, with escape sequences translated as if in a string literal.
Escape sequences are translated as follows;
Translation Escape Name Translation\b
backspace U+0008
\t
horizontal tab U+0009
\n
line feed U+000A
\f
form feed U+000C
\r
carriage return U+000D
\s
space U+0020
\"
double quote U+0022
\'
single quote U+0027
\\
backslash U+005C
\0 - \377
octal escape code point equivalents \<line-terminator>
continuation discard
\u2022
". Unicode escapes are translated by the Java compiler when reading input characters and are not part of the string literal specification.
IllegalArgumentException
- when an escape sequence is malformed.
This method allows the application of a function to
this
string. The function should expect a single String argument and produce an
R
result.
Any exception thrown by f.apply()
will be propagated to the caller.
R
- the type of the result
f
- a function to apply
This object (which is already a string!) is itself returned.
toString
in interface CharSequence
toString
in class Object
Returns a stream of
int
zero-extending the
char
values from this sequence. Any char which maps to a
surrogate code pointis passed through uninterpreted.
chars
in interface CharSequence
Returns a stream of code point values from this sequence. Any surrogate pairs encountered in the sequence are combined as if by
Character.toCodePointand the result is passed to the stream. Any other code units, including ordinary BMP characters, unpaired surrogates, and undefined code units, are zero-extended to
int
values which are then passed to the stream.
codePoints
in interface CharSequence
public char[] toCharArray()
Converts this string to a new character array.
The locale always used is the one returned by Locale.getDefault(Locale.Category)
with FORMAT
category specified.
format
- A format string
args
- Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java Virtual Machine Specification. The behaviour on a null
argument depends on the conversion.
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.
Returns a formatted string using the specified locale, format string, and arguments.
l
- The locale to apply during formatting. If l
is null
then no localization is applied.
format
- A format string
args
- Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java Virtual Machine Specification. The behaviour on a null
argument depends on the conversion.
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
Formats using this string as the format string, and the supplied arguments.
String.format(this, args)
.
args
- Arguments referenced by the format specifiers in this string.
Returns the string representation of the Object
argument.
obj
- an Object
.
null
, then a string equal to "null"
; otherwise, the value of obj.toString()
is returned.
Returns the string representation of the char
array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the returned string.
data
- the character array.
String
that contains the characters of the character array.
Returns the string representation of a specific subarray of the
char
array argument.
The offset
argument is the index of the first character of the subarray. 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 returned string.
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.
IndexOutOfBoundsException
- if offset
is negative, or count
is negative, or offset+count
is larger than data.length
.
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.
IndexOutOfBoundsException
- if offset
is negative, or count
is negative, or offset+count
is larger than data.length
.
data
- the character array.
String
that contains the characters of the character array.
Returns the string representation of the boolean
argument.
b
- a boolean
.
true
, a string equal to "true"
is returned; otherwise, a string equal to "false"
is returned.
Returns the string representation of the char
argument.
c
- a char
.
1
containing as its single character the argument c
.
Returns the string representation of the
int
argument.
The representation is exactly the one returned by the Integer.toString
method of one argument.
i
- an int
.
int
argument.
Returns the string representation of the
long
argument.
The representation is exactly the one returned by the Long.toString
method of one argument.
l
- a long
.
long
argument.
Returns the string representation of the
float
argument.
The representation is exactly the one returned by the Float.toString
method of one argument.
f
- a float
.
float
argument.
Returns the string representation of the
double
argument.
The representation is exactly the one returned by the Double.toString
method of one argument.
d
- a double
.
double
argument.
Returns a canonical representation for the string object.
A pool of strings, initially empty, is maintained privately by the class String
.
When the intern method is invoked, if the pool already contains a string equal to this String
object as determined by 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.
Returns a string whose value is the concatenation of this string repeated
count
times.
If this string is empty or count is zero then the empty string is returned.
count
- number of times to repeat
count
times or the empty string if this string is empty or count is zero
IllegalArgumentException
- if the count
is negative.
Returns an
Optional
containing the nominal descriptor for this instance, which is the instance itself.
describeConstable
in interface Constable
Optional
describing the String instance
Resolves this instance as a
ConstantDesc
, the result of which is the instance itself.
resolveConstantDesc
in interface ConstantDesc
lookup
- ignored
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