public abstract class CharBuffer extends Buffer implements Comparable<CharBuffer>, Appendable, CharSequence, Readable
A char buffer.
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
Methods for compacting
, duplicating
, and slicing
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
cb.put("text/"); cb.put(subtype); cb.put("; charset="); cb.put(enc);can, for example, be replaced by the single statement
cb.put("text/").put(subtype).put("; charset=").put(enc);
public static CharBuffer allocate(int capacity)
Allocates a new char buffer.
The new buffer's position will be zero, its limit will be its capacity, its mark will be undefined, and each of its elements will be initialized to zero. 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)
Wraps a char array into a buffer.
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
, and its mark will be undefined. 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)
Wraps a char array into a buffer.
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, and its mark will be undefined. 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
Attempts to read characters into the specified character buffer. The buffer is used as a repository of characters as-is: the only changes made are the results of a put operation. No flipping or rewinding of the buffer is performed.
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)
Wraps a character sequence into a buffer.
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)
Wraps a character sequence into a buffer.
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()
Creates a new char buffer whose content is a shared subsequence of this buffer's content.
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, and its mark will be undefined. 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()
Creates a new char buffer that shares this buffer's content.
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, and mark values 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()
Creates a new, read-only char buffer that shares this buffer's content.
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, and mark values 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()
Relative get method. Reads the char at this buffer's current position, and then increments the position.
BufferUnderflowException
- If the buffer's current position is not smaller than its limitpublic abstract CharBuffer put(char c)
Relative put method (optional operation).
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)
Absolute get method. Reads the char at the given 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)
Absolute put method (optional operation).
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)
Relative bulk get method.
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)
Relative bulk get method.
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)
Relative bulk put method (optional operation).
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)
Relative bulk put method (optional operation).
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)
Relative bulk put method (optional operation).
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)
Relative bulk put method (optional operation).
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)
Relative bulk put method (optional operation).
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()
Tells whether or not this buffer is backed by an accessible char array.
If this method returns true
then the array
and arrayOffset
methods may safely be invoked.
hasArray
in class Buffer
true
if, and only if, this buffer is backed by an array and is not read-onlypublic final char[] array()
Returns the char array that backs this buffer (optional operation).
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()
Returns the offset within this buffer's backing array of the first element of the buffer (optional operation).
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 abstract CharBuffer compact()
Compacts this buffer (optional operation).
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()
Tells whether or not this char buffer is direct.
public int hashCode()
Returns the current hash code of this buffer.
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)
Tells whether or not this buffer is equal to another object.
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)
Compares this buffer to another.
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()
Returns a string containing the characters in this buffer.
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()
Returns the length of this character buffer.
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)
Reads the character at the given index relative to the current position.
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)
Creates a new character buffer that represents the specified subsequence of this buffer, relative to the current position.
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)
Appends the specified character sequence to this buffer (optional operation).
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)
Appends a subsequence of the specified character sequence to this buffer (optional operation).
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)
Appends the specified char to this buffer (optional operation).
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()
Retrieves this buffer's byte 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()
Description copied from interface: CharSequence
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.
chars
in interface CharSequence
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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