Interface CharSequence
- All Known Subinterfaces:
Name
- All Known Implementing Classes:
-
CharBuffer
,Segment
,String
,StringBuffer
,StringBuilder
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 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.
- Since:
- 1.4
Method Summary
Modifier and Type | Method | Description |
---|---|---|
char | charAt(int index) | Returns the |
default IntStream | chars() | Returns a stream of |
default IntStream | codePoints() | Returns a stream of code point values from this sequence. |
static int | compare(CharSequence cs1,
CharSequence cs2) | Compares two |
int | length() | Returns the length of this character sequence. |
CharSequence | subSequence(int start,
int end) | Returns a |
String | toString() | Returns a string containing the characters in this sequence in the same order as this sequence. |
Method Detail
length
int length()
Returns the length of this character sequence. The length is the number of 16-bit char
s in the sequence.
- Returns:
- the number of
char
s in this sequence
charAt
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
- the index of thechar
value to be returned - Returns:
- the specified
char
value - Throws:
-
IndexOutOfBoundsException
- if theindex
argument is negative or not less thanlength()
subSequence
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.
- Parameters:
-
start
- the start index, inclusive -
end
- the end index, exclusive - Returns:
- the specified subsequence
- Throws:
-
IndexOutOfBoundsException
- ifstart
orend
are negative, ifend
is greater thanlength()
, or ifstart
is greater thanend
toString
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.
- Overrides:
-
toString
in classObject
- Returns:
- a string consisting of exactly this sequence of characters
chars
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.
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:
- an IntStream of char values from this sequence
- Since:
- 1.8
codePoints
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.
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:
- an IntStream of Unicode code points from this sequence
- Since:
- 1.8
compare
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
- the firstCharSequence
-
cs2
- the secondCharSequence
- Returns:
- the value
0
if the twoCharSequence
are equal; a negative integer if the firstCharSequence
is lexicographically less than the second; or a positive integer if the firstCharSequence
is lexicographically greater than the second. - Since:
- 11