Added in API level 1

String

class String : Serializable, Comparable<String!>, CharSequence

kotlin.Any
↳	java.lang.String

The String class represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class.

Strings are constant; their values cannot be changed after they are created. String buffers support mutable strings. Because String objects are immutable they can be shared. For example:

String str = "abc";
  

is equivalent to:

char data[] = {'a', 'b', 'c'};
      String str = new String(data);
  

Here are some more examples of how strings can be used:

System.out.println("abc");
      String cde = "cde";
      System.out.println("abc" + cde);
      String c = "abc".substring(2,3);
      String d = cde.substring(1, 2);
  

The class String includes methods for examining individual characters of the sequence, for comparing strings, for searching strings, for extracting substrings, and for creating a copy of a string with all characters translated to uppercase or to lowercase. 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 java.text.Collator class provides methods for finer-grain, locale-sensitive String comparison.

Summary

Public constructors
String() Initializes a newly created String object so that it represents an empty character sequence.
String(original: String) 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(value: CharArray!) Allocates a new String so that it represents the sequence of characters currently contained in the character array argument.
String(value: CharArray!, offset: Int, count: Int) Allocates a new String that contains characters from a subarray of the character array argument.
String(codePoints: IntArray!, offset: Int, count: Int) Allocates a new String that contains characters from a subarray of the Unicode code point array argument.
String(ascii: ByteArray!, hibyte: Int, offset: Int, count: Int) Allocates a new String constructed from a subarray of an array of 8-bit integer values.
String(ascii: ByteArray!, hibyte: Int) Allocates a new String containing characters constructed from an array of 8-bit integer values.
String(bytes: ByteArray!, offset: Int, length: Int, charsetName: String)
String(bytes: ByteArray!, offset: Int, length: Int, charset: Charset) Constructs a new String by decoding the specified subarray of bytes using the specified charset.
String(bytes: ByteArray!, charsetName: String) Constructs a new String by decoding the specified array of bytes using the specified charset.
String(bytes: ByteArray!, charset: Charset) Constructs a new String by decoding the specified array of bytes using the specified charset.
String(bytes: ByteArray!, offset: Int, length: Int) Constructs a new String by decoding the specified subarray of bytes using the platform's default charset.
String(bytes: ByteArray!) Constructs a new String by decoding the specified array of bytes using the platform's default charset.
String(buffer: StringBuffer) Allocates a new string that contains the sequence of characters currently contained in the string buffer argument.
String(builder: StringBuilder) Allocates a new string that contains the sequence of characters currently contained in the string builder argument.

Public methods
IntStream	chars() Returns a stream of int zero-extending the char values from this sequence.
Int	codePointAt(index: Int) Returns the character (Unicode code point) at the specified index.
Int	codePointBefore(index: Int) Returns the character (Unicode code point) before the specified index.
Int	codePointCount(beginIndex: Int, endIndex: Int) Returns the number of Unicode code points in the specified text range of this String.
IntStream	codePoints() Returns a stream of code point values from this sequence.
Int	compareTo(other: String) Compares two strings lexicographically.
Int	compareToIgnoreCase(str: String) Compares two strings lexicographically, ignoring case differences.
String	concat(str: String) Concatenates the specified string to the end of this string.
Boolean	contains(s: CharSequence) Returns true if and only if this string contains the specified sequence of char values.
Boolean	contentEquals(sb: StringBuffer) Compares this string to the specified StringBuffer.
Boolean	contentEquals(cs: CharSequence) Compares this string to the specified CharSequence.
static String	copyValueOf(data: CharArray!, offset: Int, count: Int) Equivalent to valueOf(char[],int,int).
static String	copyValueOf(data: CharArray!) Equivalent to valueOf(char[]).
Boolean	endsWith(suffix: String) Tests if this string ends with the specified suffix.
Boolean	equals(other: Any?) Compares this string to the specified object.
Boolean	equalsIgnoreCase(anotherString: String?) Compares this String to another String, ignoring case considerations.
static String	format(format: String, vararg args: Any!) Returns a formatted string using the specified format string and arguments.
static String	format(l: Locale, format: String, vararg args: Any!) Returns a formatted string using the specified locale, format string, and arguments.
String	formatted(vararg args: Any!) Formats using this string as the format string, and the supplied arguments.
Char	get(index: Int) Returns the char value at the specified index.
Unit	getBytes(srcBegin: Int, srcEnd: Int, dst: ByteArray!, dstBegin: Int) Copies characters from this string into the destination byte array.
ByteArray!	getBytes(charsetName: String) Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte array.
ByteArray!	getBytes(charset: Charset) Encodes this String into a sequence of bytes using the given charset, storing the result into a new byte array.
ByteArray!	getBytes() Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array.
Unit	getChars(srcBegin: Int, srcEnd: Int, dst: CharArray!, dstBegin: Int) Copies characters from this string into the destination character array.
Int	hashCode() Returns a hash code for this string.
String	indent(n: Int) Adjusts the indentation of each line of this string based on the value of n, and normalizes line termination characters.
Int	indexOf(ch: Int) Returns the index within this string of the first occurrence of the specified character.
Int	indexOf(ch: Int, fromIndex: Int) Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.
Int	indexOf(str: String) Returns the index within this string of the first occurrence of the specified substring.
Int	indexOf(str: String, fromIndex: Int) 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	isBlank() Returns true if the string is empty or contains only white space codepoints, otherwise false.
Boolean	isEmpty() Returns true if, and only if, length() is 0.
static String	join(delimiter: CharSequence, vararg elements: CharSequence!) Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.
static String	join(delimiter: CharSequence, elements: MutableIterable<CharSequence!>) Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter.
Int	lastIndexOf(ch: Int) Returns the index within this string of the last occurrence of the specified character.
Int	lastIndexOf(ch: Int, fromIndex: Int) Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index.
Int	lastIndexOf(str: String) Returns the index within this string of the last occurrence of the specified substring.
Int	lastIndexOf(str: String, fromIndex: Int) Returns the index within this string of the last occurrence of the specified substring, searching backward starting at the specified index.
Stream<String!>	lines() Returns a stream of lines extracted from this string, separated by line terminators.
Boolean	matches(regex: String) Tells whether or not this string matches the given regular expression.
Int	offsetByCodePoints(index: Int, codePointOffset: Int) Returns the index within this String that is offset from the given index by codePointOffset code points.
Boolean	regionMatches(toffset: Int, other: String, ooffset: Int, len: Int) Tests if two string regions are equal.
Boolean	regionMatches(ignoreCase: Boolean, toffset: Int, other: String, ooffset: Int, len: Int) Tests if two string regions are equal.
String	repeat(count: Int) Returns a string whose value is the concatenation of this string repeated count times.
String	replace(oldChar: Char, newChar: Char) Returns a string resulting from replacing all occurrences of oldChar in this string with newChar.
String	replace(target: CharSequence, replacement: CharSequence) Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.
String	replaceAll(regex: String, replacement: String) Replaces each substring of this string that matches the given regular expression with the given replacement.
String	replaceFirst(regex: String, replacement: String) Replaces the first substring of this string that matches the given regular expression with the given replacement.
Array<String!>	split(regex: String, limit: Int) Splits this string around matches of the given regular expression.
Array<String!>	split(regex: String) Splits this string around matches of the given regular expression.
Boolean	startsWith(prefix: String, toffset: Int) Tests if the substring of this string beginning at the specified index starts with the specified prefix.
Boolean	startsWith(prefix: String) Tests if this string starts with the specified prefix.
String	strip() Returns a string whose value is this string, with all leading and trailing white space removed.
String	stripIndent() Returns a string whose value is this string, with incidental removed from the beginning and end of every line.
String	stripLeading() Returns a string whose value is this string, with all leading white space removed.
String	stripTrailing() Returns a string whose value is this string, with all trailing white space removed.
CharSequence	subSequence(startIndex: Int, endIndex: Int) Returns a character sequence that is a subsequence of this sequence.
String	substring(beginIndex: Int) Returns a string that is a substring of this string.
String	substring(beginIndex: Int, endIndex: Int) Returns a string that is a substring of this string.
CharArray!	toCharArray() Converts this string to a new character array.
String	toLowerCase(locale: Locale) Converts all of the characters in this String to lower case using the rules of the given Locale.
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(locale: Locale) Converts all of the characters in this String to upper case using the rules of the given Locale.
String	toUpperCase() Converts all of the characters in this String to upper case using the rules of the default locale.
R	transform(f: Function<in String!, out R>) This method allows the application of a function to this string.
String	translateEscapes() Returns a string whose value is this string, with escape sequences translated as if in a string literal.
String	trim() 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).
static String	valueOf(obj: Any?) Returns the string representation of the Object argument.
static String	valueOf(data: CharArray!) Returns the string representation of the char array argument.
static String	valueOf(data: CharArray!, offset: Int, count: Int) Returns the string representation of a specific subarray of the char array argument.
static String	valueOf(b: Boolean) Returns the string representation of the boolean argument.
static String	valueOf(c: Char) Returns the string representation of the char argument.
static String	valueOf(i: Int) Returns the string representation of the int argument.
static String	valueOf(l: Long) Returns the string representation of the long argument.
static String	valueOf(f: Float) Returns the string representation of the float argument.
static String	valueOf(d: Double) Returns the string representation of the double argument.

Properties
static Comparator<String!>!	CASE_INSENSITIVE_ORDER A Comparator that orders String objects as by compareToIgnoreCase.
Int	length Returns the length of this string.

Public constructors

String

Added in API level 1

String()

Initializes a newly created String object so that it represents an empty character sequence. Note that use of this constructor is unnecessary since Strings are immutable.

String

Added in API level 1

String(original: String)

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.

Parameters
original	String: A String

String

Added in API level 1

String(value: CharArray!)

Allocates a new String so that it represents the sequence of characters currently contained in the character array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.

Parameters
value	CharArray!: The initial value of the string

String

Added in API level 1

String(
    value: CharArray!, 
    offset: Int, 
    count: Int)

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.

Parameters
value	CharArray!: Array that is the source of characters
offset	Int: The initial offset
count	Int: The length

Exceptions
java.lang.IndexOutOfBoundsException	If offset is negative, count is negative, or offset is greater than value.length - count

String

Added in API level 1

String(
    codePoints: IntArray!, 
    offset: Int, 
    count: Int)

Allocates a new String that contains characters from a subarray of the Unicode code point array argument. The offset argument is the index of the first code point of the subarray and the count argument specifies the length of the subarray. The contents of the subarray are converted to chars; subsequent modification of the int array does not affect the newly created string.

Parameters
codePoints	IntArray!: Array that is the source of Unicode code points
offset	Int: The initial offset
count	Int: The length

Exceptions
java.lang.IllegalArgumentException	If any invalid Unicode code point is found in codePoints
java.lang.IndexOutOfBoundsException	If offset is negative, count is negative, or offset is greater than codePoints.length - count

String

Added in API level 1

String(
    ascii: ByteArray!, 
    hibyte: Int, 
    offset: Int, 
    count: Int)

Deprecated: This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a , charset name, or that use the platform's default charset.

Allocates a new String constructed from a subarray of an array of 8-bit integer values.

The offset argument is the index of the first byte of the subarray, and 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.

Parameters
ascii	ByteArray!: The bytes to be converted to characters
hibyte	Int: The top 8 bits of each 16-bit Unicode code unit
offset	Int: The initial offset
count	Int: The length

Exceptions
java.lang.IndexOutOfBoundsException	If offset is negative, count is negative, or offset is greater than ascii.length - count

See Also

• #String(byte[], int)
• #String(byte[], int, int, java.lang.String)
• #String(byte[], int, int, java.nio.charset.Charset)
• #String(byte[], int, int)
• #String(byte[], java.lang.String)
• #String(byte[], java.nio.charset.Charset)
• #String(byte[])

String

Added in API level 1

String(
    ascii: ByteArray!, 
    hibyte: Int)

Deprecated: This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a , charset name, or that use the platform's default charset.

Allocates a new String containing characters constructed from an array of 8-bit integer values. Each character c in the resulting string is constructed from the corresponding component b in the byte array such that:

<b><i>c</i></b>== (char)(((hibyte & 0xff) << 8)
                          | (<b><i>b</i></b>& 0xff))
  

Parameters
ascii	ByteArray!: The bytes to be converted to characters
hibyte	Int: The top 8 bits of each 16-bit Unicode code unit

See Also

• #String(byte[], int, int, java.lang.String)
• #String(byte[], int, int, java.nio.charset.Charset)
• #String(byte[], int, int)
• #String(byte[], java.lang.String)
• #String(byte[], java.nio.charset.Charset)
• #String(byte[])

String

Added in API level 1

String(
    bytes: ByteArray!, 
    offset: Int, 
    length: Int, 
    charsetName: String)

String

Added in API level 9

String(
    bytes: ByteArray!, 
    offset: Int, 
    length: Int, 
    charset: Charset)

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 class should be used when more control over the decoding process is required.

Parameters
bytes	ByteArray!: The bytes to be decoded into characters
offset	Int: The index of the first byte to decode
length	Int: The number of bytes to decode
charset	Charset: The charset to be used to decode the bytes

Exceptions
java.lang.IndexOutOfBoundsException	If offset is negative, length is negative, or offset is greater than bytes.length - length

String

Added in API level 1

String(
    bytes: ByteArray!, 
    charsetName: String)

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 class should be used when more control over the decoding process is required.

Parameters
bytes	ByteArray!: The bytes to be decoded into characters
charsetName	String: The name of a supported charset

Exceptions
java.io.UnsupportedEncodingException	If the named charset is not supported

String

Added in API level 9

String(
    bytes: ByteArray!, 
    charset: Charset)

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 class should be used when more control over the decoding process is required.

Parameters
bytes	ByteArray!: The bytes to be decoded into characters
charset	Charset: The charset to be used to decode the bytes

String

Added in API level 1

String(
    bytes: ByteArray!, 
    offset: Int, 
    length: Int)

Constructs a new String by decoding the specified subarray of bytes using the platform's default charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the subarray.

The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The class should be used when more control over the decoding process is required.

Parameters
bytes	ByteArray!: The bytes to be decoded into characters
offset	Int: The index of the first byte to decode
length	Int: The number of bytes to decode

Exceptions
java.lang.IndexOutOfBoundsException	If offset is negative, length is negative, or offset is greater than bytes.length - length

String

Added in API level 1

String(bytes: ByteArray!)

Constructs a new String by decoding the specified array of bytes using the platform's default charset. The length of the new String is a function of the charset, and hence may not be equal to the length of the byte array.

The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The class should be used when more control over the decoding process is required.

Parameters
bytes	ByteArray!: The bytes to be decoded into characters

String

Added in API level 1

String(buffer: StringBuffer)

Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. The contents of the string buffer are copied; subsequent modification of the string buffer does not affect the newly created string.

Parameters
buffer	StringBuffer: A StringBuffer

String

Added in API level 1

String(builder: StringBuilder)

Allocates a new string that contains the sequence of characters currently contained in the string builder argument. The contents of the string builder are copied; subsequent modification of the string builder does not affect the newly created string.

This constructor is provided to ease migration to StringBuilder. Obtaining a string from a string builder via the toString method is likely to run faster and is generally preferred.

Parameters
builder	StringBuilder: A StringBuilder

Public methods

chars

Added in API level 24

fun chars(): IntStream

Returns a stream of int zero-extending the char values from this sequence. Any char which maps to a surrogate code point is passed through uninterpreted.

Return
IntStream	an IntStream of char values from this sequence

codePointAt

Added in API level 1

fun codePointAt(index: Int): Int

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.

Parameters
index	Int: the index to the char values

Return
Int	the code point value of the character at the index

Exceptions
java.lang.IndexOutOfBoundsException	if the index argument is negative or not less than the length of this string.

codePointBefore

Added in API level 1

fun codePointBefore(index: Int): Int

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.

Parameters
index	Int: the index following the code point that should be returned

Return
Int	the Unicode code point value before the given index.

Exceptions
java.lang.IndexOutOfBoundsException	if the index argument is less than 1 or greater than the length of this string.

codePointCount

Added in API level 1

fun codePointCount(
    beginIndex: Int, 
    endIndex: Int
): Int

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 chars) of the text range is endIndex-beginIndex. Unpaired surrogates within the text range count as one code point each.

Parameters
beginIndex	Int: the index to the first char of the text range.
endIndex	Int: the index after the last char of the text range.

Return
Int	the number of Unicode code points in the specified text range

Exceptions
java.lang.IndexOutOfBoundsException	if the beginIndex is negative, or endIndex is larger than the length of this String, or beginIndex is larger than endIndex.

codePoints

Added in API level 24

fun codePoints(): IntStream

Returns a stream of code point values from this sequence. Any surrogate pairs encountered in the sequence are combined as if by Character.toCodePoint and 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.

Return
IntStream	an IntStream of Unicode code points from this sequence

compareTo

Added in API level 1

fun compareTo(other: String): Int

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; returns 0 exactly when the equals(java.lang.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 java.text.Collator.

Parameters
o	the object to be compared.
anotherString	the String to be compared.

Return
Int	the value 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.

Exceptions
java.lang.NullPointerException	if the specified object is null
java.lang.ClassCastException	if the specified object's type prevents it from being compared to this object.

compareToIgnoreCase

Added in API level 1

fun compareToIgnoreCase(str: String): Int

Compares two strings lexicographically, ignoring case differences. This method returns an integer whose sign is that of calling compareTo with normalized versions of the strings where case differences have been eliminated by calling Character.toLowerCase(Character.toUpperCase(character)) on each character.

Note that this method does not take locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text.Collator class provides locale-sensitive comparison.

Parameters
str	String: the String to be compared.

Return
Int	a negative integer, zero, or a positive integer as the specified String is greater than, equal to, or less than this String, ignoring case considerations.

See Also

• java.text.Collator

concat

Added in API level 1

fun concat(str: String): String

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"
  

Parameters
str	String: the String that is concatenated to the end of this String.

Return
String	a string that represents the concatenation of this object's characters followed by the string argument's characters.

contains

Added in API level 1

fun contains(s: CharSequence): Boolean

Returns true if and only if this string contains the specified sequence of char values.

Parameters
s	CharSequence: the sequence to search for

Return
Boolean	true if this string contains s, false otherwise

contentEquals

Added in API level 1

fun contentEquals(sb: StringBuffer): Boolean

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 java.text.Collator.

Parameters
sb	StringBuffer: The StringBuffer to compare this String against

Return
Boolean	true if this String represents the same sequence of characters as the specified StringBuffer, false otherwise

contentEquals

Added in API level 1

fun contentEquals(cs: CharSequence): Boolean

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 java.text.Collator.

Parameters
cs	CharSequence: The sequence to compare this String against

Return
Boolean	true if this String represents the same sequence of char values as the specified sequence, false otherwise

copyValueOf

Added in API level 1

static fun copyValueOf(
    data: CharArray!, 
    offset: Int, 
    count: Int
): String

Equivalent to valueOf(char[],int,int).

Parameters
data	CharArray!: the character array.
offset	Int: initial offset of the subarray.
count	Int: length of the subarray.

Return
String	a String that contains the characters of the specified subarray of the character array.

Exceptions
java.lang.IndexOutOfBoundsException	if offset is negative, or count is negative, or offset+count is larger than data.length.

copyValueOf

Added in API level 1

static fun copyValueOf(data: CharArray!): String

Equivalent to valueOf(char[]).

Parameters
data	CharArray!: the character array.

Return
String	a String that contains the characters of the character array.

endsWith

Added in API level 1

fun endsWith(suffix: String): Boolean

Tests if this string ends with the specified suffix.

Parameters
suffix	String: the suffix.

Return
Boolean	true if the character sequence represented by the argument is a suffix of the character sequence represented by this object; false otherwise. Note that the result will be true if the argument is the empty string or is equal to this String object as determined by the equals(java.lang.Object) method.

equals

Added in API level 1

fun equals(other: Any?): Boolean

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 java.text.Collator.

Parameters
obj	the reference object with which to compare.
anObject	The object to compare this String against

Return
Boolean	true if the given object represents a String equivalent to this string, false otherwise

See Also

• #compareTo(String)
• #equalsIgnoreCase(String)

equalsIgnoreCase

Added in API level 1

fun equalsIgnoreCase(anotherString: String?): Boolean

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 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:

• The two characters are the same (as compared by the == operator)
• Calling Character.toLowerCase(Character.toUpperCase(char)) on each character produces the same result

Note that this method does not take locale into account, and will result in unsatisfactory results for certain locales. The java.text.Collator class provides locale-sensitive comparison.

Parameters
anotherString	String?: The String to compare this String against

Return
Boolean	true if the argument is not null and it represents an equivalent String ignoring case; false otherwise

See Also

• #equals(Object)

format

Added in API level 1

static fun format(
    format: String, 
    vararg args: Any!
): String

Returns a formatted string using the specified format string and arguments.

The locale always used is the one returned by Locale.getDefault(Locale.Category) with FORMAT category specified.

Parameters
format	String: A format string
args	Any!: 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.

Return
String	A formatted string

Exceptions
java.util.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.

See Also

• java.util.Formatter

format

Added in API level 1

static fun format(
    l: Locale, 
    format: String, 
    vararg args: Any!
): String

Returns a formatted string using the specified locale, format string, and arguments.

Parameters
l	Locale: The locale to apply during formatting. If l is null then no localization is applied.
format	String: A format string
args	Any!: 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.

Return
String	A formatted string

Exceptions
java.util.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

See Also

• java.util.Formatter

formatted

Added in API level 34

fun formatted(vararg args: Any!): String

Formats using this string as the format string, and the supplied arguments.

Parameters
args	Any!: Arguments referenced by the format specifiers in this string.

Return
String	A formatted string

See Also

• java.lang.String#format(String,Object...)
• java.util.Formatter

get

Added in API level 1

fun get(index: Int): Char

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.

Parameters
index	Int: the index of the char value.

Return
Char	the char value at the specified index of this string. The first char value is at index 0.

Exceptions
java.lang.IndexOutOfBoundsException	if the index argument is negative or not less than length()
java.lang.IndexOutOfBoundsException	if the index argument is negative or not less than the length of this string.

getBytes

Added in API level 1
Deprecated in API level 15

fun getBytes(
    srcBegin: Int, 
    srcEnd: Int, 
    dst: ByteArray!, 
    dstBegin: Int
): Unit

Deprecated: This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via the getBytes() method, which uses the platform's default charset.

Copies characters from this string into the destination byte array. Each byte receives the 8 low-order bits of the corresponding character. The eight high-order bits of each character are not copied and do not participate in the transfer in any way.

The first character to be copied is at index srcBegin; the last character to be copied is at 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
  

Parameters
srcBegin	Int: Index of the first character in the string to copy
srcEnd	Int: Index after the last character in the string to copy
dst	ByteArray!: The destination array
dstBegin	Int: The start offset in the destination array

Exceptions
java.lang.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

getBytes

Added in API level 1

fun getBytes(charsetName: String): ByteArray!

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 class should be used when more control over the encoding process is required.

Parameters
charsetName	String: The name of a supported charset

Return
ByteArray!	The resultant byte array

Exceptions
java.io.UnsupportedEncodingException	If the named charset is not supported

getBytes

Added in API level 9

fun getBytes(charset: Charset): ByteArray!

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 java.nio.charset.CharsetEncoder class should be used when more control over the encoding process is required.

Parameters
charset	Charset: The java.nio.charset.Charset to be used to encode the String

Return
ByteArray!	The resultant byte array

getBytes

Added in API level 1

fun getBytes(): ByteArray!

Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array.

The behavior of this method when this string cannot be encoded in the default charset is unspecified. The class should be used when more control over the encoding process is required.

Return
ByteArray!	The resultant byte array

getChars

Added in API level 1

fun getChars(
    srcBegin: Int, 
    srcEnd: Int, 
    dst: CharArray!, 
    dstBegin: Int
): Unit

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
  

Parameters
srcBegin	Int: index of the first character in the string to copy.
srcEnd	Int: index after the last character in the string to copy.
dst	CharArray!: the destination array.
dstBegin	Int: the start offset in the destination array.

Exceptions
java.lang.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

hashCode

Added in API level 1

fun hashCode(): Int

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.)

Return
Int	a hash code value for this object.

indent

Added in API level 34

fun indent(n: Int): String

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 String#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.

Parameters
n	Int: number of leading white space characters to add or remove

Return
String	string with indentation adjusted and line endings normalized

See Also

• java.lang.String#lines()
• java.lang.String#isBlank()
• java.lang.Character#isWhitespace(int)

indexOf

Added in API level 1

fun indexOf(ch: Int): Int

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 k such that:

this.charAt(<i>k</i>) == ch
  

is true. For other values of ch, it is the smallest value k such that:

this.codePointAt(<i>k</i>) == ch
  

is true. In either case, if no such character occurs in this string, then -1 is returned.

Parameters
ch	Int: a character (Unicode code point).

Return
Int	the index of the first occurrence of the character in the character sequence represented by this object, or -1 if the character does not occur.

indexOf

Added in API level 1

fun indexOf(
    ch: Int, 
    fromIndex: Int
): Int

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(<i>k</i>) == ch) <code>&amp;&amp;</code>(<i>k</i>>= fromIndex)
  

is true. For other values of ch, it is the smallest value k such that:

(this.codePointAt(<i>k</i>) == ch) <code>&amp;&amp;</code>(<i>k</i>>= 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).

Parameters
ch	Int: a character (Unicode code point).
fromIndex	Int: the index to start the search from.

Return
Int	the index of the first occurrence of the character in the character sequence represented by this object that is greater than or equal to fromIndex, or -1 if the character does not occur.

indexOf

Added in API level 1

fun indexOf(str: String): Int

Returns the index within this string of the first occurrence of the specified substring.

The returned index is the smallest value k for which:

<code>this.startsWith(str, k)
  </code>

If no such value of k exists, then -1 is returned.

Parameters
str	String: the substring to search for.

Return
Int	the index of the first occurrence of the specified substring, or -1 if there is no such occurrence.

indexOf

Added in API level 1

fun indexOf(
    str: String, 
    fromIndex: Int
): Int

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:

<code>k &gt;= Math.min(fromIndex, this.length()) &amp;&amp;
                    this.startsWith(str, k)
  </code>

If no such value of k exists, then -1 is returned.

Parameters
str	String: the substring to search for.
fromIndex	Int: the index from which to start the search.

Return
Int	the index of the first occurrence of the specified substring, starting at the specified index, or -1 if there is no such occurrence.

intern

Added in API level 1

fun intern(): String

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(java.lang.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.

Return
String	a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.

isBlank

Added in API level 33

fun isBlank(): Boolean

Returns true if the string is empty or contains only white space codepoints, otherwise false.

Return
Boolean	true if the string is empty or contains only white space codepoints, otherwise false

See Also

• java.lang.Character#isWhitespace(int)

isEmpty

Added in API level 9

fun isEmpty(): Boolean

Returns true if, and only if, length() is 0.

Return
Boolean	true if length() is 0, otherwise false

join

Added in API level 26

static fun join(
    delimiter: CharSequence, 
    vararg elements: CharSequence!
): String

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter. For example,

<code>String message = String.join("-", "Java", "is", "cool");
      // message returned is: "Java-is-cool"
  </code>

Note that if an element is null, then "null" is added.

Parameters
delimiter	CharSequence: the delimiter that separates each element
elements	CharSequence!: the elements to join together.

Return
String	a new String that is composed of the elements separated by the delimiter

Exceptions
java.lang.NullPointerException	If delimiter or elements is null

See Also

• java.util.StringJoiner

join

Added in API level 26

static fun join(
    delimiter: CharSequence, 
    elements: MutableIterable<CharSequence!>
): String

Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter. For example,

<code>List&lt;String&gt; strings = List.of("Java", "is", "cool");
      String message = String.join(" ", strings);
      //message returned is: "Java is cool"
 
      Set&lt;String&gt; strings =
          new LinkedHashSet&lt;&gt;(List.of("Java", "is", "very", "cool"));
      String message = String.join("-", strings);
      //message returned is: "Java-is-very-cool"
  </code>

Note that if an individual element is null, then "null" is added.

Parameters
delimiter	CharSequence: a sequence of characters that is used to separate each of the elements in the resulting String
elements	MutableIterable<CharSequence!>: an Iterable that will have its elements joined together.

Return
String	a new String that is composed from the elements argument

Exceptions
java.lang.NullPointerException	If delimiter or elements is null

See Also

• #join(CharSequence,CharSequence...)
• java.util.StringJoiner

lastIndexOf

Added in API level 1

fun lastIndexOf(ch: Int): Int

Returns the index within this string of the last occurrence of the specified character. For values of ch in the range from 0 to 0xFFFF (inclusive), the index (in Unicode code units) returned is the largest value k such that:

this.charAt(<i>k</i>) == ch
  

is true. For other values of ch, it is the largest value k such that:

this.codePointAt(<i>k</i>) == 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.

Parameters
ch	Int: a character (Unicode code point).

Return
Int	the index of the last occurrence of the character in the character sequence represented by this object, or -1 if the character does not occur.

lastIndexOf

Added in API level 1

fun lastIndexOf(
    ch: Int, 
    fromIndex: Int
): Int

Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. For values of ch in the range from 0 to 0xFFFF (inclusive), the index returned is the largest value k such that:

(this.charAt(<i>k</i>) == ch) <code>&amp;&amp;</code>(<i>k</i><= fromIndex)
  

is true. For other values of ch, it is the largest value k such that:

(this.codePointAt(<i>k</i>) == ch) <code>&amp;&amp;</code>(<i>k</i><= 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).

Parameters
ch	Int: a character (Unicode code point).
fromIndex	Int: 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.

Return
Int	the index of the last occurrence of the character in the character sequence represented by this object that is less than or equal to fromIndex, or -1 if the character does not occur before that point.

lastIndexOf

Added in API level 1

fun lastIndexOf(str: String): Int

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:

<code>this.startsWith(str, k)
  </code>

If no such value of k exists, then -1 is returned.

Parameters
str	String: the substring to search for.

Return
Int	the index of the last occurrence of the specified substring, or -1 if there is no such occurrence.

lastIndexOf

Added in API level 1

fun lastIndexOf(
    str: String, 
    fromIndex: Int
): Int

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:

<code>k &lt;= Math.min(fromIndex, this.length()) &amp;&amp;
                    this.startsWith(str, k)
  </code>

If no such value of k exists, then -1 is returned.

Parameters
str	String: the substring to search for.
fromIndex	Int: the index to start the search from.

Return
Int	the index of the last occurrence of the specified substring, searching backward from the specified index, or -1 if there is no such occurrence.

lines

Added in API level 33

fun lines(): Stream<String!>

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.

Return
Stream<String!>	the stream of lines extracted from this string

matches

Added in API level 1

fun matches(regex: String): Boolean

Tells whether or not this string matches the given regular expression.

An invocation of this method of the form str.matches(regex) yields exactly the same result as the expression

java.util.regex.Pattern. matches(regex, str)

Parameters
regex	String: the regular expression to which this string is to be matched

Return
Boolean	true if, and only if, this string matches the given regular expression

Exceptions
java.util.regex.PatternSyntaxException	if the regular expression's syntax is invalid

See Also

• java.util.regex.Pattern

offsetByCodePoints

Added in API level 1

fun offsetByCodePoints(
    index: Int, 
    codePointOffset: Int
): Int

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.

Parameters
index	Int: the index to be offset
codePointOffset	Int: the offset in code points

Return
Int	the index within this String

Exceptions
java.lang.IndexOutOfBoundsException	if index is negative or larger then the length of this String, or if codePointOffset is positive and the substring starting with index has fewer than codePointOffset code points, or if codePointOffset is negative and the substring before index has fewer than the absolute value of codePointOffset code points.

regionMatches

Added in API level 1

fun regionMatches(
    toffset: Int, 
    other: String, 
    ooffset: Int, 
    len: Int
): Boolean

Tests if two string regions are equal.

A substring of this String object is compared to a substring of the argument other. The result is true if these substrings represent identical character sequences. The substring of this String object to be compared begins at index toffset and has length len. The substring of other to be compared begins at index ooffset and has length len. The result is false if and only if at least one of the following is true:

• toffset is negative.
• ooffset is negative.
• toffset+len is greater than the length of this String object.
• ooffset+len is greater than the length of the other argument.
• There is some nonnegative integer k less than len such that: this.charAt(toffset + k) != other.charAt(ooffset + k)

Note that this method does not take locale into account. The java.text.Collator class provides locale-sensitive comparison.

Parameters
toffset	Int: the starting offset of the subregion in this string.
other	String: the string argument.
ooffset	Int: the starting offset of the subregion in the string argument.
len	Int: the number of characters to compare.

Return
Boolean	true if the specified subregion of this string exactly matches the specified subregion of the string argument; false otherwise.

regionMatches

Added in API level 1

fun regionMatches(
    ignoreCase: Boolean, 
    toffset: Int, 
    other: String, 
    ooffset: Int, 
    len: Int
): Boolean

Tests if two string regions are equal.

A substring of this String object is compared to a substring of the argument other. The result is true if these substrings represent character sequences that are the same, ignoring case if and only if ignoreCase is true. The substring of this String object to be compared begins at index toffset and has length len. The substring of other to be compared begins at index ooffset and has length len. The result is false if and only if at least one of the following is true:

• toffset is negative.
• ooffset is negative.
• toffset+len is greater than the length of this String object.
• ooffset+len is greater than the length of the other argument.
• ignoreCase is false and there is some nonnegative integer k less than len such that:

  this.charAt(toffset+k) != other.charAt(ooffset+k)
    

• ignoreCase is true and there is some nonnegative integer k less than len such that:

  Character.toLowerCase(Character.toUpperCase(this.charAt(toffset+k))) !=
   Character.toLowerCase(Character.toUpperCase(other.charAt(ooffset+k)))
    

Note that this method does not take locale into account, and will result in unsatisfactory results for certain locales when ignoreCase is true. The java.text.Collator class provides locale-sensitive comparison.

Parameters
ignoreCase	Boolean: if true, ignore case when comparing characters.
toffset	Int: the starting offset of the subregion in this string.
other	String: the string argument.
ooffset	Int: the starting offset of the subregion in the string argument.
len	Int: the number of characters to compare.

Return
Boolean	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.

repeat

Added in API level 33

fun repeat(count: Int): String

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.

Parameters
count	Int: number of times to repeat

Return
String	A string composed of this string repeated count times or the empty string if this string is empty or count is zero

Exceptions
java.lang.IllegalArgumentException	if the count is negative.

replace

Added in API level 1

fun replace(
    oldChar: Char, 
    newChar: Char
): 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)
  

Parameters
oldChar	Char: the old character.
newChar	Char: the new character.

Return
String	a string derived from this string by replacing every occurrence of oldChar with newChar.

replace

Added in API level 1

fun replace(
    target: CharSequence, 
    replacement: CharSequence
): String

Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence. The replacement proceeds from the beginning of the string to the end, for example, replacing "aa" with "b" in the string "aaa" will result in "ba" rather than "ab".

Parameters
target	CharSequence: The sequence of char values to be replaced
replacement	CharSequence: The replacement sequence of char values

Return
String	The resulting string

replaceAll

Added in API level 1

fun replaceAll(
    regex: String, 
    replacement: String
): String

Replaces each substring of this string that matches the given regular expression with the given replacement.

An invocation of this method of the form str.replaceAll(regex, repl) yields exactly the same result as the expression

java.util.regex.Pattern.java.util.regex.Pattern#compile(regex).matcher(str).java.util.regex.Matcher#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 java.util.regex.Matcher#replaceAll. Use java.util.regex.Matcher#quoteReplacement to suppress the special meaning of these characters, if desired.

Parameters
regex	String: the regular expression to which this string is to be matched
replacement	String: the string to be substituted for each match

Return
String	The resulting String

Exceptions
java.util.regex.PatternSyntaxException	if the regular expression's syntax is invalid

See Also

• java.util.regex.Pattern

replaceFirst

Added in API level 1

fun replaceFirst(
    regex: String, 
    replacement: String
): String

Replaces the first substring of this string that matches the given regular expression with the given replacement.

An invocation of this method of the form str.replaceFirst(regex, repl) yields exactly the same result as the expression

java.util.regex.Pattern.java.util.regex.Pattern#compile(regex).matcher(str).java.util.regex.Matcher#replaceFirst(repl)

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; see java.util.regex.Matcher#replaceFirst. Use java.util.regex.Matcher#quoteReplacement to suppress the special meaning of these characters, if desired.

Parameters
regex	String: the regular expression to which this string is to be matched
replacement	String: the string to be substituted for the first match

Return
String	The resulting String

Exceptions
java.util.regex.PatternSyntaxException	if the regular expression's syntax is invalid

See Also

• java.util.regex.Pattern

split

Added in API level 1

fun split(
    regex: String, 
    limit: Int
): Array<String!>

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

java.util.regex.Pattern.java.util.regex.Pattern#compile(regex).split(str, n)

Parameters
regex	String: the delimiting regular expression
limit	Int: the result threshold, as described above

Return
Array<String!>	the array of strings computed by splitting this string around matches of the given regular expression

Exceptions
java.util.regex.PatternSyntaxException	if the regular expression's syntax is invalid

See Also

• java.util.regex.Pattern

split

Added in API level 1

fun split(regex: String): Array<String!>

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" }

Parameters
regex	String: the delimiting regular expression

Return
Array<String!>	the array of strings computed by splitting this string around matches of the given regular expression

Exceptions
java.util.regex.PatternSyntaxException	if the regular expression's syntax is invalid

See Also

• java.util.regex.Pattern

startsWith

Added in API level 1

fun startsWith(
    prefix: String, 
    toffset: Int
): Boolean

Tests if the substring of this string beginning at the specified index starts with the specified prefix.

Parameters
prefix	String: the prefix.
toffset	Int: where to begin looking in this string.

Return
Boolean	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)

startsWith

Added in API level 1

fun startsWith(prefix: String): Boolean

Tests if this string starts with the specified prefix.

Parameters
prefix	String: the prefix.

Return
Boolean	true if the character sequence represented by the argument is a prefix of the character sequence represented by this string; false otherwise. Note also that true will be returned if the argument is an empty string or is equal to this String object as determined by the equals(java.lang.Object) method.

strip

Added in API level 33

fun strip(): String

Returns a string whose value is this string, with all leading and trailing white space removed.

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.

Return
String	a string whose value is this string, with all leading and trailing white space removed

See Also

• java.lang.Character#isWhitespace(int)

stripIndent

Added in API level 34

fun stripIndent(): String

Returns a string whose value is this string, with incidental removed 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 space as 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 line is 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 String#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 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.

Return
String	string with incidental indentation removed and line terminators normalized

See Also

• java.lang.String#lines()
• java.lang.String#isBlank()
• java.lang.String#indent(int)
• java.lang.Character#isWhitespace(int)

stripLeading

Added in API level 33

fun stripLeading(): String

Returns a string whose value is this string, with all leading white space removed.

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 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.

Return
String	a string whose value is this string, with all leading white space removed

See Also

• java.lang.Character#isWhitespace(int)

stripTrailing

Added in API level 33

fun stripTrailing(): String

Returns a string whose value is this string, with all trailing white space removed.

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.

Return
String	a string whose value is this string, with all trailing white space removed

See Also

• java.lang.Character#isWhitespace(int)

subSequence

Added in API level 1

fun subSequence(
    startIndex: Int, 
    endIndex: Int
): CharSequence

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)

Parameters
start	the start index, inclusive
end	the end index, exclusive
beginIndex	the begin index, inclusive.
endIndex	Int: the end index, exclusive.

Return
CharSequence	the specified subsequence.

Exceptions
java.lang.IndexOutOfBoundsException	if beginIndex or endIndex is negative, if endIndex is greater than length(), or if beginIndex is greater than endIndex

substring

Added in API level 1

fun substring(beginIndex: Int): String

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)
  

Parameters
beginIndex	Int: the beginning index, inclusive.

Return
String	the specified substring.

Exceptions
java.lang.IndexOutOfBoundsException	if beginIndex is negative or larger than the length of this String object.

substring

Added in API level 1

fun substring(
    beginIndex: Int, 
    endIndex: Int
): String

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"
  

Parameters
beginIndex	Int: the beginning index, inclusive.
endIndex	Int: the ending index, exclusive.

Return
String	the specified substring.

Exceptions
java.lang.IndexOutOfBoundsException	if the beginIndex is negative, or endIndex is larger than the length of this String object, or beginIndex is larger than endIndex.

toCharArray

Added in API level 1

fun toCharArray(): CharArray!

Converts this string to a new character array.

Return
CharArray!	a newly allocated character array whose length is the length of this string and whose contents are initialized to contain the character sequence represented by this string.

toLowerCase

Added in API level 1

fun toLowerCase(locale: Locale): String

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 may be a different length than the original String.

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 String

Parameters
locale	Locale: use the case transformation rules for this locale

Return
String	the String, converted to lowercase.

See Also

• java.lang.String#toLowerCase()
• java.lang.String#toUpperCase()
• java.lang.String#toUpperCase(Locale)

toLowerCase

Added in API level 1

fun toLowerCase(): String

Converts all of the characters in this String to lower case using the rules of the default locale. This is equivalent to calling toLowerCase(Locale.getDefault()).

Note: This method is locale sensitive, and may produce unexpected results if used for strings that are intended to be interpreted locale independently. Examples are programming language identifiers, protocol keys, and HTML tags. For instance, "TITLE".toLowerCase() in a Turkish locale returns "t\u005Cu0131tle", where '\u005Cu0131' is the LATIN SMALL LETTER DOTLESS I character. To obtain correct results for locale insensitive strings, use toLowerCase(Locale.ROOT).

Return
String	the String, converted to lowercase.

See Also

• java.lang.String#toLowerCase(Locale)

toString

Added in API level 1

fun toString(): String

This object (which is already a string!) is itself returned.

Return
String	the string itself.

toUpperCase

Added in API level 1

fun toUpperCase(locale: Locale): String

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 may be a different length than the original String.

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	FAHRVERGNÜGEN

Parameters
locale	Locale: use the case transformation rules for this locale

Return
String	the String, converted to uppercase.

See Also

• java.lang.String#toUpperCase()
• java.lang.String#toLowerCase()
• java.lang.String#toLowerCase(Locale)

toUpperCase

Added in API level 1

fun toUpperCase(): String

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()).

Note: This method is locale sensitive, and may produce unexpected results if used for strings that are intended to be interpreted locale independently. Examples are programming language identifiers, protocol keys, and HTML tags. For instance, "title".toUpperCase() in a Turkish locale returns "T\u005Cu0130TLE", where '\u005Cu0130' is the LATIN CAPITAL LETTER I WITH DOT ABOVE character. To obtain correct results for locale insensitive strings, use toUpperCase(Locale.ROOT).

Return
String	the String, converted to uppercase.

See Also

• java.lang.String#toUpperCase(Locale)

transform

Added in API level 34

fun <R : Any!> transform(f: Function<in String!, out R>): R

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.

Parameters
f	Function<in String!, out R>: a function to apply
<R>	the type of the result

Return
R	the result of applying the function to this string

See Also

• java.util.function.Function

translateEscapes

Added in API level 34

fun translateEscapes(): String

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
\u005Cb	backspace	U+0008
\u005Ct	horizontal tab	U+0009
\u005Cn	line feed	U+000A
\u005Cf	form feed	U+000C
\u005Cr	carriage return	U+000D
\u005Cs	space	U+0020
\u005C"	double quote	U+0022
\u005C'	single quote	U+0027
\u005C\u005C	backslash	U+005C
\u005C0 - \u005C377	octal escape	code point equivalents
\u005C<line-terminator>	continuation	discard

Return
String	String with escape sequences translated.

Exceptions
java.lang.IllegalArgumentException	when an escape sequence is malformed.

trim

Added in API level 1

fun trim(): String

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.

Return
String	a string whose value is this string, with all leading and trailing space removed, or this string if it has no leading or trailing space.

valueOf

Added in API level 1

static fun valueOf(obj: Any?): String

Returns the string representation of the Object argument.

Parameters
obj	Any?: an Object.

Return
String	if the argument is null, then a string equal to "null"; otherwise, the value of obj.toString() is returned.

See Also

• java.lang.Object#toString()

valueOf

Added in API level 1

static fun valueOf(data: CharArray!): String

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.

Parameters
data	CharArray!: the character array.

Return
String	a String that contains the characters of the character array.

valueOf

Added in API level 1

static fun valueOf(
    data: CharArray!, 
    offset: Int, 
    count: Int
): String

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.

Parameters
data	CharArray!: the character array.
offset	Int: initial offset of the subarray.
count	Int: length of the subarray.

Return
String	a String that contains the characters of the specified subarray of the character array.

Exceptions
java.lang.IndexOutOfBoundsException	if offset is negative, or count is negative, or offset+count is larger than data.length.

valueOf

Added in API level 1

static fun valueOf(b: Boolean): String

Returns the string representation of the boolean argument.

Parameters
b	Boolean: a boolean.

Return
String	if the argument is true, a string equal to "true" is returned; otherwise, a string equal to "false" is returned.

valueOf

Added in API level 1

static fun valueOf(c: Char): String

Returns the string representation of the char argument.

Parameters
c	Char: a char.

Return
String	a string of length 1 containing as its single character the argument c.

valueOf

Added in API level 1

static fun valueOf(i: Int): String

Returns the string representation of the int argument.

The representation is exactly the one returned by the Integer.toString method of one argument.

Parameters
i	Int: an int.

Return
String	a string representation of the int argument.

See Also

• java.lang.Integer#toString(int, int)

valueOf

Added in API level 1

static fun valueOf(l: Long): String

Returns the string representation of the long argument.

The representation is exactly the one returned by the Long.toString method of one argument.

Parameters
l	Long: a long.

Return
String	a string representation of the long argument.

See Also

• java.lang.Long#toString(long)

valueOf

Added in API level 1

static fun valueOf(f: Float): String

Returns the string representation of the float argument.

The representation is exactly the one returned by the Float.toString method of one argument.

Parameters
f	Float: a float.

Return
String	a string representation of the float argument.

See Also

• java.lang.Float#toString(float)

valueOf

Added in API level 1

static fun valueOf(d: Double): String

Returns the string representation of the double argument.

The representation is exactly the one returned by the Double.toString method of one argument.

Parameters
d	Double: a double.

Return
String	a string representation of the double argument.

See Also

• java.lang.Double#toString(double)

Properties

CASE_INSENSITIVE_ORDER

Added in API level 1

static val CASE_INSENSITIVE_ORDER: Comparator<String!>!

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 java.text.Collator class provides locale-sensitive comparison.

See Also

• java.text.Collator

length

Added in API level 1

val length: Int

Returns the length of this string. The length is equal to the number of Unicode code units in the string.

Return
Int	the length of the sequence of characters represented by this object.