Added in API level 1

Summary: Methods

CharSequence

public interface CharSequence

java.lang.CharSequence

Known indirect subclasses

AlteredCharSequence, CharBuffer, DateIntervalFormat.FormattedDateInterval, Editable, FormattedNumber, FormattedNumberRange, FormattedValue, GetChars, ListFormatter.FormattedList, PrecomputedText, RelativeDateTimeFormatter.FormattedRelativeDateTime, Spannable, SpannableString, SpannableStringBuilder, Spanned, SpannedString, String, StringBuffer, StringBuilder

AlteredCharSequence	This class was deprecated in API level 30. The functionality this class offers is easily implemented outside the framework.
CharBuffer	A char buffer.
DateIntervalFormat.FormattedDateInterval	An immutable class containing the result of a date interval formatting operation.
Editable	This is the interface for text whose content and markup can be changed (as opposed to immutable text like Strings).
FormattedNumber	The result of a number formatting operation.
FormattedNumberRange	The result of a number range formatting operation.
FormattedValue	An abstract formatted value: a string with associated field attributes.
GetChars	Please implement this interface if your CharSequence has a getChars() method like the one in String that is faster than calling charAt() multiple times.
ListFormatter.FormattedList	An immutable class containing the result of a list formatting operation.
PrecomputedText	A text which has the character metrics data.
RelativeDateTimeFormatter.FormattedRelativeDateTime	Represents the result of a formatting operation of a relative datetime.
Spannable	This is the interface for text to which markup objects can be attached and detached.
SpannableString	This is the class for text whose content is immutable but to which markup objects can be attached and detached.
SpannableStringBuilder	This is the class for text whose content and markup can both be changed.
Spanned	This is the interface for text that has markup objects attached to ranges of it.
SpannedString	This is the class for text whose content and markup are immutable.
String	The `String` class represents character strings.
StringBuffer	A thread-safe, mutable sequence of characters.
StringBuilder	A mutable sequence of characters.

A CharSequence is a readable sequence of char values. This interface provides uniform, read-only access to many different kinds of char sequences. A char value represents a character in the Basic Multilingual Plane (BMP) or a surrogate. Refer to Unicode Character Representation for details.

This interface does not refine the general contracts of the equals and hashCode methods. The result of testing two objects that implement CharSequence for equality is therefore, in general, undefined. Each object may be implemented by a different class, and there is no guarantee that each class will be capable of testing its instances for equality with those of the other. It is therefore inappropriate to use arbitrary CharSequence instances as elements in a set or as keys in a map.

Summary

Public methods
`abstract char`	`charAt(int index)` Returns the `char` value at the specified index.
`default IntStream`	`chars()` Returns a stream of `int` zero-extending the `char` values from this sequence.
`default IntStream`	`codePoints()` Returns a stream of code point values from this sequence.
`static int`	`compare(CharSequence cs1, CharSequence cs2)` Compares two `CharSequence` instances lexicographically.
`default boolean`	`isEmpty()` Returns `true` if this character sequence is empty.
`abstract int`	`length()` Returns the length of this character sequence.
`abstract CharSequence`	`subSequence(int start, int end)` Returns a `CharSequence` that is a subsequence of this sequence.
`abstract String`	`toString()` Returns a string containing the characters in this sequence in the same order as this sequence.

Public methods

charAt

Added in API level 1

public abstract char charAt (int index)

Returns the char value at the specified index. An index ranges from zero to length() - 1. The first char value of the sequence is at index zero, the next at index one, 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 to be returned

Returns
`char`	the specified `char` value

Throws
`IndexOutOfBoundsException`	if the `index` argument is negative or not less than `length()`

chars

Added in API level 24

public IntStream chars ()

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.

The stream binds to this sequence when the terminal stream operation commences (specifically, for mutable sequences the spliterator for the stream is late-binding). If the sequence is modified during that operation then the result is undefined.

Returns
`IntStream`	an IntStream of char values from this sequence

codePoints

Added in API level 24

public IntStream codePoints ()

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.

Returns
`IntStream`	an IntStream of Unicode code points from this sequence

compare

Added in API level 34

public static int compare (CharSequence cs1, 
                CharSequence cs2)

Compares two CharSequence instances lexicographically. Returns a negative value, zero, or a positive value if the first sequence is lexicographically less than, equal to, or greater than the second, respectively.

The lexicographical ordering of CharSequence is defined as follows. Consider a CharSequence cs of length len to be a sequence of char values, cs[0] to cs[len-1]. Suppose k is the lowest index at which the corresponding char values from each sequence differ. The lexicographic ordering of the sequences is determined by a numeric comparison of the char values cs1[k] with cs2[k]. If there is no such index k, the shorter sequence is considered lexicographically less than the other. If the sequences have the same length, the sequences are considered lexicographically equal.

Parameters
`cs1`	`CharSequence`: the first `CharSequence`
`cs2`	`CharSequence`: the second `CharSequence`

Returns
`int`	the value `0` if the two `CharSequence` are equal; a negative integer if the first `CharSequence` is lexicographically less than the second; or a positive integer if the first `CharSequence` is lexicographically greater than the second.

isEmpty

Added in API level 35

public boolean isEmpty ()

Returns true if this character sequence is empty.

Implementation Requirements:

The default implementation returns the result of calling length() == 0.

Returns
`boolean`	`true` if `length()` is `0`, otherwise `false`

length

Added in API level 1

public abstract int length ()

Returns the length of this character sequence. The length is the number of 16-bit chars in the sequence.

Returns
`int`	the number of `char`s in this sequence

subSequence

Added in API level 1

public abstract CharSequence subSequence (int start, 
                int end)

Returns a CharSequence that is a subsequence of this sequence. The subsequence starts with the char value at the specified index and ends with the char value at index end - 1. The length (in chars) of the returned sequence is end - start, so if start == end then an empty sequence is returned.

Parameters
`start`	`int`: the start index, inclusive
`end`	`int`: the end index, exclusive

Returns
`CharSequence`	the specified subsequence

Throws
`IndexOutOfBoundsException`	if `start` or `end` are negative, if `end` is greater than `length()`, or if `start` is greater than `end`

toString

Added in API level 1

public abstract String toString ()

Returns a string containing the characters in this sequence in the same order as this sequence. The length of the string will be the length of this sequence.

Returns
`String`	a string consisting of exactly this sequence of characters