public interface CharSequence
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 comparing two objects that implement CharSequence
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.
int length()
Returns the length of this character sequence. The length is the number of 16-bit char
s in the sequence.
char
s in this sequencechar 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.
index
- the index of the char
value to be returnedchar
valueIndexOutOfBoundsException
- if the index
argument is negative or not less than length()
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 char
s) of the returned sequence is end - start
, so if start == end
then an empty sequence is returned.
start
- the start index, inclusiveend
- the end index, exclusiveIndexOutOfBoundsException
- if start
or end
are negative, if end
is greater than length()
, or if start
is greater than end
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.
toString
in class Object
default 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.
If the sequence is mutated while the stream is being read, the result is undefined.
default 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.
If the sequence is mutated while the stream is being read, the result is undefined.
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