Appendable
, CharSequence
, Comparable<CharBuffer>
, Readable
public abstract class CharBuffer extends Buffer implements Comparable<CharBuffer>, Appendable, CharSequence, Readable
This class defines four categories of operations upon char buffers:
Absolute and relative get
and
put
methods that read and write
single chars;
Relative bulk get
methods that transfer contiguous sequences of chars from this buffer
into an array; and
Relative bulk put
methods that transfer contiguous sequences of chars from a
char array, a string, or some other char
buffer into this buffer; and
A method for compacting
a char buffer.
Char buffers can be created either by allocation
, which allocates space for the buffer's
content, by wrapping
an existing
char array or string into a buffer, or by creating a
view of an existing byte buffer.
Like a byte buffer, a char buffer is either direct or non-direct. A
char buffer created via the wrap
methods of this class will
be non-direct. A char buffer created as a view of a byte buffer will
be direct if, and only if, the byte buffer itself is direct. Whether or not
a char buffer is direct may be determined by invoking the isDirect
method.
This class implements the CharSequence
interface so that
character buffers may be used wherever character sequences are accepted, for
example in the regular-expression package java.util.regex
.
Methods in this class that do not otherwise have a value to return are specified to return the buffer upon which they are invoked. This allows method invocations to be chained. The sequence of statements
can, for example, be replaced by the single statementcb.put("text/"); cb.put(subtype); cb.put("; charset="); cb.put(enc);
cb.put("text/").put(subtype).put("; charset=").put(enc);
Modifier and Type | Method | Description |
---|---|---|
static CharBuffer |
allocate(int capacity) |
Allocates a new char buffer.
|
CharBuffer |
append(char c) |
Appends the specified char to this
buffer (optional operation).
|
CharBuffer |
append(CharSequence csq) |
Appends the specified character sequence to this
buffer (optional operation).
|
CharBuffer |
append(CharSequence csq,
int start,
int end) |
Appends a subsequence of the specified character sequence to this
buffer (optional operation).
|
char[] |
array() |
Returns the char array that backs this
buffer (optional operation).
|
int |
arrayOffset() |
Returns the offset within this buffer's backing array of the first
element of the buffer (optional operation).
|
abstract CharBuffer |
asReadOnlyBuffer() |
Creates a new, read-only char buffer that shares this buffer's
content.
|
char |
charAt(int index) |
Reads the character at the given index relative to the current
position.
|
IntStream |
chars() |
Returns a stream of
int zero-extending the char values
from this sequence. |
CharBuffer |
clear() |
Clears this buffer.
|
abstract CharBuffer |
compact() |
Compacts this buffer (optional operation).
|
int |
compareTo(CharBuffer that) |
Compares this buffer to another.
|
abstract CharBuffer |
duplicate() |
Creates a new char buffer that shares this buffer's content.
|
boolean |
equals(Object ob) |
Tells whether or not this buffer is equal to another object.
|
CharBuffer |
flip() |
Flips this buffer.
|
abstract char |
get() |
Relative get method.
|
CharBuffer |
get(char[] dst) |
Relative bulk get method.
|
CharBuffer |
get(char[] dst,
int offset,
int length) |
Relative bulk get method.
|
abstract char |
get(int index) |
Absolute get method.
|
boolean |
hasArray() |
Tells whether or not this buffer is backed by an accessible char
array.
|
int |
hashCode() |
Returns the current hash code of this buffer.
|
abstract boolean |
isDirect() |
Tells whether or not this char buffer is direct.
|
int |
length() |
Returns the length of this character buffer.
|
CharBuffer |
limit(int newLimit) |
Sets this buffer's limit.
|
CharBuffer |
mark() |
Sets this buffer's mark at its position.
|
abstract ByteOrder |
order() |
Retrieves this buffer's byte order.
|
CharBuffer |
position(int newPosition) |
Sets this buffer's position.
|
abstract CharBuffer |
put(char c) |
Relative put method (optional operation).
|
CharBuffer |
put(char[] src) |
Relative bulk put method (optional operation).
|
CharBuffer |
put(char[] src,
int offset,
int length) |
Relative bulk put method (optional operation).
|
abstract CharBuffer |
put(int index,
char c) |
Absolute put method (optional operation).
|
CharBuffer |
put(String src) |
Relative bulk put method (optional operation).
|
CharBuffer |
put(String src,
int start,
int end) |
Relative bulk put method (optional operation).
|
CharBuffer |
put(CharBuffer src) |
Relative bulk put method (optional operation).
|
int |
read(CharBuffer target) |
Attempts to read characters into the specified character buffer.
|
CharBuffer |
reset() |
Resets this buffer's position to the previously-marked position.
|
CharBuffer |
rewind() |
Rewinds this buffer.
|
abstract CharBuffer |
slice() |
Creates a new char buffer whose content is a shared subsequence of
this buffer's content.
|
abstract CharBuffer |
subSequence(int start,
int end) |
Creates a new character buffer that represents the specified subsequence
of this buffer, relative to the current position.
|
String |
toString() |
Returns a string containing the characters in this buffer.
|
static CharBuffer |
wrap(char[] array) |
Wraps a char array into a buffer.
|
static CharBuffer |
wrap(char[] array,
int offset,
int length) |
Wraps a char array into a buffer.
|
static CharBuffer |
wrap(CharSequence csq) |
Wraps a character sequence into a buffer.
|
static CharBuffer |
wrap(CharSequence csq,
int start,
int end) |
Wraps a character sequence into a buffer.
|
capacity, hasRemaining, isReadOnly, limit, position, remaining
codePoints
public static CharBuffer allocate(int capacity)
The new buffer's position will be zero, its limit will be its
capacity, its mark will be undefined, each of its elements will be
initialized to zero, and its byte order will be
the native order
of the underlying
hardware.
It will have a backing array
, and its
array offset
will be zero.
capacity
- The new buffer's capacity, in charsIllegalArgumentException
- If the capacity
is a negative integerpublic static CharBuffer wrap(char[] array, int offset, int length)
The new buffer will be backed by the given char array;
that is, modifications to the buffer will cause the array to be modified
and vice versa. The new buffer's capacity will be
array.length
, its position will be offset
, its limit
will be offset + length
, its mark will be undefined, and its
byte order will be
the native order
of the underlying
hardware.
Its backing array
will be the given array, and
its array offset
will be zero.
array
- The array that will back the new bufferoffset
- The offset of the subarray to be used; must be non-negative and
no larger than array.length
. The new buffer's position
will be set to this value.length
- The length of the subarray to be used;
must be non-negative and no larger than
array.length - offset
.
The new buffer's limit will be set to offset + length
.IndexOutOfBoundsException
- If the preconditions on the offset
and length
parameters do not holdpublic static CharBuffer wrap(char[] array)
The new buffer will be backed by the given char array;
that is, modifications to the buffer will cause the array to be modified
and vice versa. The new buffer's capacity and limit will be
array.length
, its position will be zero, its mark will be
undefined, and its byte order will be
the native order
of the underlying
hardware.
Its backing array
will be the given array, and its
array offset
will be zero.
array
- The array that will back this bufferpublic int read(CharBuffer target) throws IOException
read
in interface Readable
target
- the buffer to read characters intoIOException
- if an I/O error occursNullPointerException
- if target is nullReadOnlyBufferException
- if target is a read only bufferpublic static CharBuffer wrap(CharSequence csq, int start, int end)
The content of the new, read-only buffer will be the content of the
given character sequence. The buffer's capacity will be
csq.length()
, its position will be start
, its limit
will be end
, and its mark will be undefined.
csq
- The character sequence from which the new character buffer is to
be createdstart
- The index of the first character to be used;
must be non-negative and no larger than csq.length()
.
The new buffer's position will be set to this value.end
- The index of the character following the last character to be
used; must be no smaller than start
and no larger
than csq.length()
.
The new buffer's limit will be set to this value.IndexOutOfBoundsException
- If the preconditions on the start
and end
parameters do not holdpublic static CharBuffer wrap(CharSequence csq)
The content of the new, read-only buffer will be the content of the
given character sequence. The new buffer's capacity and limit will be
csq.length()
, its position will be zero, and its mark will be
undefined.
csq
- The character sequence from which the new character buffer is to
be createdpublic abstract CharBuffer slice()
The content of the new buffer will start at this buffer's current position. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.
The new buffer's position will be zero, its capacity and its limit will be the number of chars remaining in this buffer, its mark will be undefined, and its byte order will be identical to that of this buffer. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.
public abstract CharBuffer duplicate()
The content of the new buffer will be that of this buffer. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.
The new buffer's capacity, limit, position, mark values, and byte order will be identical to those of this buffer. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.
public abstract CharBuffer asReadOnlyBuffer()
The content of the new buffer will be that of this buffer. Changes to this buffer's content will be visible in the new buffer; the new buffer itself, however, will be read-only and will not allow the shared content to be modified. The two buffers' position, limit, and mark values will be independent.
The new buffer's capacity, limit, position, mark values, and byte order will be identical to those of this buffer.
If this buffer is itself read-only then this method behaves in
exactly the same way as the duplicate
method.
public abstract char get()
BufferUnderflowException
- If the buffer's current position is not smaller than its limitpublic abstract CharBuffer put(char c)
Writes the given char into this buffer at the current position, and then increments the position.
c
- The char to be writtenBufferOverflowException
- If this buffer's current position is not smaller than its limitReadOnlyBufferException
- If this buffer is read-onlypublic abstract char get(int index)
index
- The index from which the char will be readIndexOutOfBoundsException
- If index
is negative
or not smaller than the buffer's limitpublic abstract CharBuffer put(int index, char c)
Writes the given char into this buffer at the given index.
index
- The index at which the char will be writtenc
- The char value to be writtenIndexOutOfBoundsException
- If index
is negative
or not smaller than the buffer's limitReadOnlyBufferException
- If this buffer is read-onlypublic CharBuffer get(char[] dst, int offset, int length)
This method transfers chars from this buffer into the given
destination array. If there are fewer chars remaining in the
buffer than are required to satisfy the request, that is, if
length
>
remaining()
, then no
chars are transferred and a BufferUnderflowException
is
thrown.
Otherwise, this method copies length
chars from this
buffer into the given array, starting at the current position of this
buffer and at the given offset in the array. The position of this
buffer is then incremented by length
.
In other words, an invocation of this method of the form
src.get(dst, off, len)
has exactly the same effect as
the loop
for (int i = off; i < off + len; i++)
dst[i] = src.get():
except that it first checks that there are sufficient chars in
this buffer and it is potentially much more efficient.dst
- The array into which chars are to be writtenoffset
- The offset within the array of the first char to be
written; must be non-negative and no larger than
dst.length
length
- The maximum number of chars to be written to the given
array; must be non-negative and no larger than
dst.length - offset
BufferUnderflowException
- If there are fewer than length
chars
remaining in this bufferIndexOutOfBoundsException
- If the preconditions on the offset
and length
parameters do not holdpublic CharBuffer get(char[] dst)
This method transfers chars from this buffer into the given
destination array. An invocation of this method of the form
src.get(a)
behaves in exactly the same way as the invocation
src.get(a, 0, a.length)
dst
- The destination arrayBufferUnderflowException
- If there are fewer than length
chars
remaining in this bufferpublic CharBuffer put(CharBuffer src)
This method transfers the chars remaining in the given source
buffer into this buffer. If there are more chars remaining in the
source buffer than in this buffer, that is, if
src.remaining()
>
remaining()
,
then no chars are transferred and a BufferOverflowException
is thrown.
Otherwise, this method copies
n = src.remaining()
chars from the given
buffer into this buffer, starting at each buffer's current position.
The positions of both buffers are then incremented by n.
In other words, an invocation of this method of the form
dst.put(src)
has exactly the same effect as the loop
while (src.hasRemaining()) dst.put(src.get());except that it first checks that there is sufficient space in this buffer and it is potentially much more efficient.
src
- The source buffer from which chars are to be read;
must not be this bufferBufferOverflowException
- If there is insufficient space in this buffer
for the remaining chars in the source bufferIllegalArgumentException
- If the source buffer is this bufferReadOnlyBufferException
- If this buffer is read-onlypublic CharBuffer put(char[] src, int offset, int length)
This method transfers chars into this buffer from the given
source array. If there are more chars to be copied from the array
than remain in this buffer, that is, if
length
>
remaining()
, then no
chars are transferred and a BufferOverflowException
is
thrown.
Otherwise, this method copies length
chars from the
given array into this buffer, starting at the given offset in the array
and at the current position of this buffer. The position of this buffer
is then incremented by length
.
In other words, an invocation of this method of the form
dst.put(src, off, len)
has exactly the same effect as
the loop
for (int i = off; i < off + len; i++)
dst.put(a[i]);
except that it first checks that there is sufficient space in this
buffer and it is potentially much more efficient.src
- The array from which chars are to be readoffset
- The offset within the array of the first char to be read;
must be non-negative and no larger than array.length
length
- The number of chars to be read from the given array;
must be non-negative and no larger than
array.length - offset
BufferOverflowException
- If there is insufficient space in this bufferIndexOutOfBoundsException
- If the preconditions on the offset
and length
parameters do not holdReadOnlyBufferException
- If this buffer is read-onlypublic final CharBuffer put(char[] src)
This method transfers the entire content of the given source
char array into this buffer. An invocation of this method of the
form dst.put(a)
behaves in exactly the same way as the
invocation
dst.put(a, 0, a.length)
src
- The source arrayBufferOverflowException
- If there is insufficient space in this bufferReadOnlyBufferException
- If this buffer is read-onlypublic CharBuffer put(String src, int start, int end)
This method transfers chars from the given string into this
buffer. If there are more chars to be copied from the string than
remain in this buffer, that is, if
end - start
>
remaining()
,
then no chars are transferred and a BufferOverflowException
is thrown.
Otherwise, this method copies
n = end
- start
chars
from the given string into this buffer, starting at the given
start
index and at the current position of this buffer. The
position of this buffer is then incremented by n.
In other words, an invocation of this method of the form
dst.put(src, start, end)
has exactly the same effect
as the loop
for (int i = start; i < end; i++)
dst.put(src.charAt(i));
except that it first checks that there is sufficient space in this
buffer and it is potentially much more efficient.src
- The string from which chars are to be readstart
- The offset within the string of the first char to be read;
must be non-negative and no larger than
string.length()
end
- The offset within the string of the last char to be read,
plus one; must be non-negative and no larger than
string.length()
BufferOverflowException
- If there is insufficient space in this bufferIndexOutOfBoundsException
- If the preconditions on the start
and end
parameters do not holdReadOnlyBufferException
- If this buffer is read-onlypublic final CharBuffer put(String src)
This method transfers the entire content of the given source string
into this buffer. An invocation of this method of the form
dst.put(s)
behaves in exactly the same way as the invocation
dst.put(s, 0, s.length())
src
- The source stringBufferOverflowException
- If there is insufficient space in this bufferReadOnlyBufferException
- If this buffer is read-onlypublic final boolean hasArray()
If this method returns true
then the array
and arrayOffset
methods may safely be invoked.
public final char[] array()
Modifications to this buffer's content will cause the returned array's content to be modified, and vice versa.
Invoke the hasArray
method before invoking this
method in order to ensure that this buffer has an accessible backing
array.
array
in class Buffer
ReadOnlyBufferException
- If this buffer is backed by an array but is read-onlyUnsupportedOperationException
- If this buffer is not backed by an accessible arraypublic final int arrayOffset()
If this buffer is backed by an array then buffer position p
corresponds to array index p + arrayOffset()
.
Invoke the hasArray
method before invoking this
method in order to ensure that this buffer has an accessible backing
array.
arrayOffset
in class Buffer
ReadOnlyBufferException
- If this buffer is backed by an array but is read-onlyUnsupportedOperationException
- If this buffer is not backed by an accessible arraypublic final CharBuffer position(int newPosition)
public final CharBuffer limit(int newLimit)
public final CharBuffer mark()
public final CharBuffer reset()
Invoking this method neither changes nor discards the mark's value.
public final CharBuffer clear()
Invoke this method before using a sequence of channel-read or put operations to fill this buffer. For example:
buf.clear(); // Prepare buffer for reading in.read(buf); // Read data
This method does not actually erase the data in the buffer, but it is named as if it did because it will most often be used in situations in which that might as well be the case.
public final CharBuffer flip()
After a sequence of channel-read or put operations, invoke this method to prepare for a sequence of channel-write or relative get operations. For example:
buf.put(magic); // Prepend header in.read(buf); // Read data into rest of buffer buf.flip(); // Flip buffer out.write(buf); // Write header + data to channel
This method is often used in conjunction with the compact
method when transferring data from
one place to another.
public final CharBuffer rewind()
Invoke this method before a sequence of channel-write or get operations, assuming that the limit has already been set appropriately. For example:
out.write(buf); // Write remaining data buf.rewind(); // Rewind buffer buf.get(array); // Copy data into array
public abstract CharBuffer compact()
The chars between the buffer's current position and its limit,
if any, are copied to the beginning of the buffer. That is, the
char at index p = position()
is copied
to index zero, the char at index p + 1 is copied
to index one, and so forth until the char at index
limit()
- 1 is copied to index
n = limit()
- 1
- p.
The buffer's position is then set to n+1 and its limit is set to
its capacity. The mark, if defined, is discarded.
The buffer's position is set to the number of chars copied, rather than to zero, so that an invocation of this method can be followed immediately by an invocation of another relative put method.
ReadOnlyBufferException
- If this buffer is read-onlypublic abstract boolean isDirect()
public int hashCode()
The hash code of a char buffer depends only upon its remaining
elements; that is, upon the elements from position()
up to, and
including, the element at limit()
- 1
.
Because buffer hash codes are content-dependent, it is inadvisable to use buffers as keys in hash maps or similar data structures unless it is known that their contents will not change.
hashCode
in class Object
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public boolean equals(Object ob)
Two char buffers are equal if, and only if,
They have the same element type,
They have the same number of remaining elements, and
The two sequences of remaining elements, considered independently of their starting positions, are pointwise equal.
A char buffer is not equal to any other type of object.
equals
in class Object
ob
- The object to which this buffer is to be comparedtrue
if, and only if, this buffer is equal to the
given objectObject.hashCode()
,
HashMap
public int compareTo(CharBuffer that)
Two char buffers are compared by comparing their sequences of
remaining elements lexicographically, without regard to the starting
position of each sequence within its corresponding buffer.
Pairs of char
elements are compared as if by invoking
Character.compare(char,char)
.
A char buffer is not comparable to any other type of object.
compareTo
in interface Comparable<CharBuffer>
that
- the object to be compared.public String toString()
The first character of the resulting string will be the character at
this buffer's position, while the last character will be the character
at index limit()
- 1. Invoking this method does not
change the buffer's position.
toString
in interface CharSequence
toString
in class Object
public final int length()
When viewed as a character sequence, the length of a character
buffer is simply the number of characters between the position
(inclusive) and the limit (exclusive); that is, it is equivalent to
remaining()
.
length
in interface CharSequence
public final char charAt(int index)
charAt
in interface CharSequence
index
- The index of the character to be read, relative to the position;
must be non-negative and smaller than remaining()
position() + index
IndexOutOfBoundsException
- If the preconditions on index
do not holdpublic abstract CharBuffer subSequence(int start, int end)
The new buffer will share this buffer's content; that is, if the
content of this buffer is mutable then modifications to one buffer will
cause the other to be modified. The new buffer's capacity will be that
of this buffer, its position will be
position()
+ start
, and its limit will be
position()
+ end
. The new buffer will be
direct if, and only if, this buffer is direct, and it will be read-only
if, and only if, this buffer is read-only.
subSequence
in interface CharSequence
start
- The index, relative to the current position, of the first
character in the subsequence; must be non-negative and no larger
than remaining()
end
- The index, relative to the current position, of the character
following the last character in the subsequence; must be no
smaller than start
and no larger than
remaining()
IndexOutOfBoundsException
- If the preconditions on start
and end
do not holdpublic CharBuffer append(CharSequence csq)
An invocation of this method of the form dst.append(csq)
behaves in exactly the same way as the invocation
dst.put(csq.toString())
Depending on the specification of toString
for the
character sequence csq
, the entire sequence may not be
appended. For instance, invoking the toString
method of a character buffer will return a subsequence whose
content depends upon the buffer's position and limit.
append
in interface Appendable
csq
- The character sequence to append. If csq
is
null
, then the four characters "null"
are
appended to this character buffer.BufferOverflowException
- If there is insufficient space in this bufferReadOnlyBufferException
- If this buffer is read-onlypublic CharBuffer append(CharSequence csq, int start, int end)
An invocation of this method of the form dst.append(csq, start,
end)
when csq
is not null
, behaves in exactly the
same way as the invocation
dst.put(csq.subSequence(start, end).toString())
append
in interface Appendable
csq
- The character sequence from which a subsequence will be
appended. If csq
is null
, then characters
will be appended as if csq
contained the four
characters "null"
.start
- The index of the first character in the subsequenceend
- The index of the character following the last character in the
subsequenceBufferOverflowException
- If there is insufficient space in this bufferIndexOutOfBoundsException
- If start
or end
are negative, start
is greater than end
, or end
is greater than
csq.length()
ReadOnlyBufferException
- If this buffer is read-onlypublic CharBuffer append(char c)
An invocation of this method of the form dst.append(c)
behaves in exactly the same way as the invocation
dst.put(c)
append
in interface Appendable
c
- The 16-bit char to appendBufferOverflowException
- If there is insufficient space in this bufferReadOnlyBufferException
- If this buffer is read-onlypublic abstract ByteOrder order()
The byte order of a char buffer created by allocation or by
wrapping an existing char
array is the native order
of the underlying
hardware. The byte order of a char buffer created as a view of a byte buffer is that of the
byte buffer at the moment that the view is created.
public IntStream chars()
CharSequence
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.
chars
in interface CharSequence
Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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DRAFT 9-internal+0-adhoc.mlchung.jdk9-jdeps