java.nio
Class CharBuffer

java.lang.Object
  java.nio.Buffer
      java.nio.CharBuffer

All Implemented Interfaces:

Appendable, CharSequence, Comparable<CharBuffer>, Readable

Direct Known Subclasses:

CharArrayBuffer, CharSequenceAdapter, CharToByteBufferAdapter

public abstract class CharBuffer
extends Buffer
implements Comparable<CharBuffer>, CharSequence, Appendable, Readable

A buffer of chars.

A char buffer can be created in either of the following ways:

• Allocate a new char array and create a buffer based on it;
• Wrap an existing char array to create a new buffer;
• Wrap an existing char sequence to create a new buffer;
• Use ByteBuffer.asCharBuffer to create a char buffer based on a byte buffer.

Field Summary

Fields inherited from class java.nio.Buffer

_elementSizeShift, capacity, limit, mark, position, UNSET_MARK

Constructor Summary

CharBuffer(int capacity)
Constructs a CharBuffer with given capacity.

Method Summary

(package private) Object	_array() Returns the array associated with this buffer, or null if none exists.
(package private) int	_arrayOffset() Returns the offset into the backing array, if one exists, otherwise 0.
static CharBuffer	allocate(int capacity) Creates a char buffer based on a new allocated char array.
CharBuffer	append(char c) Append the given character.
CharBuffer	append(CharSequence csq) Append the given CharSequence.
CharBuffer	append(CharSequence csq, int start, int end) Append part of the given CharSequence.
char[]	array() Returns the char array which this buffer is based on, if there's one.
int	arrayOffset() Returns the offset of the char array which this buffer is based on, if there's one.
abstract CharBuffer	asReadOnlyBuffer() Returns a readonly buffer that shares content with this buffer.
char	charAt(int index) Returns the character located at the specified index in the buffer.
abstract CharBuffer	compact() Compacts this char buffer.
int	compareTo(CharBuffer otherBuffer) Compare the remaining chars of this buffer to another char buffer's remaining chars.
abstract CharBuffer	duplicate() Returns a duplicated buffer that shares content with this buffer.
boolean	equals(Object other) Tests whether this char buffer equals to another object.
abstract char	get() Returns the char at the current position and increase the position by 1.
CharBuffer	get(char[] dest) Reads chars from the current position into the specified char array and increase the position by the number of chars read.
CharBuffer	get(char[] dest, int off, int len) Reads chars from the current position into the specified char array, starting from the specified offset, and increase the position by the number of chars read.
abstract char	get(int index) Returns a char at the specified index, and the position is not changed.
boolean	hasArray() Returns whether this buffer is based on a char array and is read/write.
int	hashCode() Hash code is calculated from the remaining chars.
abstract boolean	isDirect() Returns true if this buffer is direct.
int	length() Returns the number of remaining chars.
abstract ByteOrder	order() Returns the byte order used by this buffer when converting chars from/to bytes.
(package private) abstract char[]	protectedArray() Child class implements this method to realize array().
(package private) abstract int	protectedArrayOffset() Child class implements this method to realize arrayOffset().
(package private) abstract boolean	protectedHasArray() Child class implements this method to realize hasArray().
abstract CharBuffer	put(char c) Writes the given char to the current position and increase the position by 1.
CharBuffer	put(char[] src) Writes chars in the given char array to the current position and increase the position by the number of chars written.
CharBuffer	put(char[] src, int off, int len) Writes chars in the given char array, starting from the specified offset, to the current position and increase the position by the number of chars written.
CharBuffer	put(CharBuffer src) Writes all the remaining chars of the src char buffer to this buffer's current position, and increase both buffers' position by the number of chars copied.
abstract CharBuffer	put(int index, char c) Write a char to the specified index of this buffer and the position is not changed.
CharBuffer	put(String str) Write all chars of the give string to the current position of this buffer, and increase the position by the length of string.
CharBuffer	put(String str, int start, int end) Write chars of the given string to the current position of this buffer, and increase the position by the number of chars written.
int	read(CharBuffer target) Reads the characters into the given CharBuffer.
abstract CharBuffer	slice() Returns a sliced buffer that shares content with this buffer.
abstract CharSequence	subSequence(int start, int end) Returns a new char buffer represents a sub-sequence of this buffer's current remaining content.
String	toString() Returns a string represents the current remaining chars of this buffer.
static CharBuffer	wrap(char[] array) Creates a new char buffer by wrapping the given char array.
static CharBuffer	wrap(char[] array, int start, int len) Creates new a char buffer by wrapping the given char array.
static CharBuffer	wrap(CharSequence chseq) Creates a new char buffer by wrapping the given char sequence.
static CharBuffer	wrap(CharSequence chseq, int start, int end) Creates a new char buffer by wrapping the given char sequence.

Methods inherited from class java.nio.Buffer

capacity, clear, flip, hasRemaining, isReadOnly, limit, limit, mark, position, position, remaining, reset, rewind

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CharBuffer

CharBuffer(int capacity)

Constructs a CharBuffer with given capacity.

Parameters:

capacity - The capacity of the buffer

Method Detail

allocate

public static CharBuffer allocate(int capacity)

Creates a char buffer based on a new allocated char array.

Parameters:

capacity - The capacity of the new buffer

Returns:

The created char buffer

Throws:

IllegalArgumentException - If capacity is less than zero

wrap

public static CharBuffer wrap(char[] array)

Creates a new char buffer by wrapping the given char array.

Calling this method has the same effect as wrap(array, 0, array.length).

Parameters:

array - The char array which the new buffer will be based on

Returns:

The created char buffer

wrap

public static CharBuffer wrap(char[] array,
                              int start,
                              int len)

Creates new a char buffer by wrapping the given char array.

The new buffer's position will be start, limit will be start + len, capacity will be the length of the array.

Parameters:

array - The char array which the new buffer will be based on

start - The start index, must be no less than zero and no greater than array.length

len - The length, must be no less than zero and no greater than array.length - start

Returns:

The created char buffer

Throws:

IndexOutOfBoundsException - If either start or len is invalid

wrap

public static CharBuffer wrap(CharSequence chseq)

Creates a new char buffer by wrapping the given char sequence.

Calling this method has the same effect as wrap(chseq, 0, chseq.length()).

Parameters:

chseq - The char sequence which the new buffer will be based on

Returns:

The created char buffer

wrap

public static CharBuffer wrap(CharSequence chseq,
                              int start,
                              int end)

Creates a new char buffer by wrapping the given char sequence.

The new buffer's position will be start, limit will be end, capacity will be the length of the char sequence. The new buffer is readonly.

Parameters:

chseq - The char sequence which the new buffer will be based on

start - The start index, must be no less than zero and no greater than chseq.length()

end - The end index, must be no less than start and no greater than chseq.length()

Returns:

The created char buffer

Throws:

IndexOutOfBoundsException - If either start or end is invalid

array

public final char[] array()

Returns the char array which this buffer is based on, if there's one.

Returns:

The char array which this buffer is based on

Throws:

ReadOnlyBufferException - If this buffer is based on an array, but it is readonly

UnsupportedOperationException - If this buffer is not based on an array

arrayOffset

public final int arrayOffset()

Returns the offset of the char array which this buffer is based on, if there's one.

The offset is the index of the array corresponds to the zero position of the buffer.

Returns:

The offset of the char array which this buffer is based on

Throws:

ReadOnlyBufferException - If this buffer is based on an array, but it is readonly

UnsupportedOperationException - If this buffer is not based on an array

_array

Object _array()

Description copied from class: Buffer

Returns the array associated with this buffer, or null if none exists. Each typed subclass (ByteBuffer, CharBuffer, etc.) overrides this method to call its array() method with appropriate checks.

Overrides:

_array in class Buffer

Returns:

a primitive array or null

_arrayOffset

int _arrayOffset()

Description copied from class: Buffer

Returns the offset into the backing array, if one exists, otherwise 0. Each typed subclass (ByteBuffer, CharBuffer, etc.) overrides this method to call its arrayOffset() method with appropriate checks.

Overrides:

_arrayOffset in class Buffer

Returns:

the array offset, or 0

asReadOnlyBuffer

public abstract CharBuffer asReadOnlyBuffer()

Returns a readonly buffer that shares content with this buffer.

The returned buffer is guaranteed to be a new instance, even this buffer is readonly itself. The new buffer's position, limit, capacity and mark are the same as this buffer.

The new buffer shares content with this buffer, which means this buffer's change of content will be visible to the new buffer. The two buffer's position, limit and mark are independent.

Returns:

A readonly version of this buffer.

charAt

public final char charAt(int index)

Returns the character located at the specified index in the buffer. The index value is referenced from the current buffer position.

Specified by:

charAt in interface CharSequence

Parameters:

index - The index referenced from the current buffer position. It must not be less than zero but less than the value obtained from a call to remaining()

Returns:

the character located at the specified index (referenced from the current position) in the buffer.

Throws:

IndexOutOfBoundsException - If the index is invalid

compact

public abstract CharBuffer compact()

Compacts this char buffer.

The remaining chars will be moved to the head of the buffer, staring from position zero. Then the position is set to remaining(); the limit is set to capacity; the mark is cleared.

Returns:

This buffer

Throws:

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

compareTo

public int compareTo(CharBuffer otherBuffer)

Compare the remaining chars of this buffer to another char buffer's remaining chars.

Specified by:

compareTo in interface Comparable<CharBuffer>

Parameters:

otherBuffer - Another char buffer

Returns:

a negative value if this is less than other; 0 if this equals to other; a positive value if this is greater than other

Throws:

ClassCastException - If other is not a char buffer

duplicate

public abstract CharBuffer duplicate()

Returns a duplicated buffer that shares content with this buffer.

The duplicated buffer's position, limit, capacity and mark are the same as this buffer. The duplicated buffer's readonly property and byte order are same as this buffer too.

The new buffer shares content with this buffer, which means either buffer's change of content will be visible to the other. The two buffer's position, limit and mark are independent.

Returns:

A duplicated buffer that shares content with this buffer.

equals

public boolean equals(Object other)

Tests whether this char buffer equals to another object.

If other is not a char buffer, then false is returned.

Two char buffers are equals if, and only if, their remaining chars are exactly the same. Position, limit, capacity and mark are not considered.

Overrides:

equals in class Object

Parameters:

other - the object to be compared against

Returns:

Whether this char buffer equals to another object.

See Also:

Object.hashCode()

get

public abstract char get()

Returns the char at the current position and increase the position by 1.

Returns:

The char at the current position.

Throws:

BufferUnderflowException - If the position is equal or greater than limit

get

public CharBuffer get(char[] dest)

Reads chars from the current position into the specified char array and increase the position by the number of chars read.

Calling this method has the same effect as get(dest, 0, dest.length).

Parameters:

dest - The destination char array

Returns:

This buffer

Throws:

BufferUnderflowException - if dest.length is greater than remaining()

get

public CharBuffer get(char[] dest,
                      int off,
                      int len)

Reads chars from the current position into the specified char array, starting from the specified offset, and increase the position by the number of chars read.

Parameters:

dest - The target char array

off - The offset of the char array, must be no less than zero and no greater than dest.length

len - The number of chars to read, must be no less than zero and no greater than dest.length - off

Returns:

This buffer

Throws:

IndexOutOfBoundsException - If either off or len is invalid

BufferUnderflowException - If len is greater than remaining()

get

public abstract char get(int index)

Returns a char at the specified index, and the position is not changed.

Parameters:

index - The index, must be no less than zero and less than limit

Returns:

A char at the specified index.

Throws:

IndexOutOfBoundsException - If index is invalid

hasArray

public final boolean hasArray()

Returns whether this buffer is based on a char array and is read/write.

If this buffer is readonly, then false is returned.

Returns:

Whether this buffer is based on a char array and is read/write.

hashCode

public int hashCode()

Hash code is calculated from the remaining chars.

Position, limit, capacity and mark don't affect the hash code.

Overrides:

hashCode in class Object

Returns:

The hash code calculated from the remaining chars.

See Also:

Object.equals(java.lang.Object)

isDirect

public abstract boolean isDirect()

Returns true if this buffer is direct.

A direct buffer will try its best to take advantage of native memory APIs and it may not stay in java heap, thus not affected by GC.

A char buffer is direct, if it is based on a byte buffer and the byte buffer is direct.

Returns:

True if this buffer is direct.

length

public final int length()

Returns the number of remaining chars.

Specified by:

length in interface CharSequence

Returns:

The number of remaining chars.

order

public abstract ByteOrder order()

Returns the byte order used by this buffer when converting chars from/to bytes.

If this buffer is not based on a byte buffer, then always return the platform's native byte order.

Returns:

The byte order used by this buffer when converting chars from/to bytes.

protectedArray

abstract char[] protectedArray()

Child class implements this method to realize array().

Returns:

see array()

protectedArrayOffset

abstract int protectedArrayOffset()

Child class implements this method to realize arrayOffset().

Returns:

see arrayOffset()

protectedHasArray

abstract boolean protectedHasArray()

Child class implements this method to realize hasArray().

Returns:

see hasArray()

put

public abstract CharBuffer put(char c)

Writes the given char to the current position and increase the position by 1.

Parameters:

c - The char to write

Returns:

This buffer

Throws:

BufferOverflowException - If position is equal or greater than limit

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

put

public final CharBuffer put(char[] src)

Writes chars in the given char array to the current position and increase the position by the number of chars written.

Calling this method has the same effect as put(src, 0, src.length).

Parameters:

src - The source char array

Returns:

This buffer

Throws:

BufferOverflowException - If remaining() is less than src.length

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

put

public CharBuffer put(char[] src,
                      int off,
                      int len)

Writes chars in the given char array, starting from the specified offset, to the current position and increase the position by the number of chars written.

Parameters:

src - The source char array

off - The offset of char array, must be no less than zero and no greater than src.length

len - The number of chars to write, must be no less than zero and no greater than src.length - off

Returns:

This buffer

Throws:

BufferOverflowException - If remaining() is less than len

IndexOutOfBoundsException - If either off or len is invalid

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

put

public CharBuffer put(CharBuffer src)

Writes all the remaining chars of the src char buffer to this buffer's current position, and increase both buffers' position by the number of chars copied.

Parameters:

src - The source char buffer

Returns:

This buffer

Throws:

BufferOverflowException - If src.remaining() is greater than this buffer's remaining()

IllegalArgumentException - If src is this buffer

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

put

public abstract CharBuffer put(int index,
                               char c)

Write a char to the specified index of this buffer and the position is not changed.

Parameters:

index - The index, must be no less than zero and less than the limit

c - The char to write

Returns:

This buffer

Throws:

IndexOutOfBoundsException - If index is invalid

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

put

public final CharBuffer put(String str)

Write all chars of the give string to the current position of this buffer, and increase the position by the length of string.

Calling this method has the same effect as put(str, 0, str.length()).

Parameters:

str - The string to write

Returns:

This buffer

Throws:

BufferOverflowException - If remaining() is less than the length of string

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

put

public CharBuffer put(String str,
                      int start,
                      int end)

Write chars of the given string to the current position of this buffer, and increase the position by the number of chars written.

Parameters:

str - The string to write

start - The first char to write, must be no less than zero and no greater than str.length()

end - The last char to write (excluding), must be less than start and no greater than str.length()

Returns:

This buffer

Throws:

BufferOverflowException - If remaining is less than end - start

IndexOutOfBoundsException - If either start or end is invalid

ReadOnlyBufferException - If no changes may be made to the contents of this buffer

slice

public abstract CharBuffer slice()

Returns a sliced buffer that shares content with this buffer.

The sliced buffer's capacity will be this buffer's remaining(), and its zero position will correspond to this buffer's current position. The new buffer's position will be 0, limit will be its capacity, and its mark is unset. The new buffer's readonly property and byte order are same as this buffer.

The new buffer shares content with this buffer, which means either buffer's change of content will be visible to the other. The two buffer's position, limit and mark are independent.

Returns:

A sliced buffer that shares content with this buffer.

subSequence

public abstract CharSequence subSequence(int start,
                                         int end)

Returns a new char buffer represents a sub-sequence of this buffer's current remaining content.

The new buffer's position will be position() + start, limit will be position() + end, capacity will be same as this buffer. The new buffer's readonly property and byte order are same as this buffer.

The new buffer shares content with this buffer, which means either buffer's change of content will be visible to the other. The two buffer's position, limit and mark are independent.

Specified by:

subSequence in interface CharSequence

Parameters:

start - The start index of the sub-sequence, referenced from the current buffer position. Must not be less than zero and not greater than the value obtained from a call to remaining().

end - The end index of the sub-sequence, referenced from the current buffer position. Must not be less than start and not be greater than the value obtained from a call to remaining()

Returns:

A new char buffer represents a sub-sequence of this buffer's current remaining content.

Throws:

IndexOutOfBoundsException - If either start or end is invalid

toString

public String toString()

Returns a string represents the current remaining chars of this buffer.

Specified by:

toString in interface CharSequence

Overrides:

toString in class Object

Returns:

A string represents the current remaining chars of this buffer.

append

public CharBuffer append(char c)

Description copied from interface: Appendable

Append the given character.

Specified by:

append in interface Appendable

Parameters:

c - the character to append

Returns:

this Appendable

See Also:

Appendable.append(char)

append

public CharBuffer append(CharSequence csq)

Description copied from interface: Appendable

Append the given CharSequence.

The behaviour of this method depends on the implementation class of Appendable.

If the give CharSequence is null, the sequence is treated as String "null".

Specified by:

append in interface Appendable

Parameters:

csq - the CharSequence to be append

Returns:

this Appendable

See Also:

Appendable.append(CharSequence)

append

public CharBuffer append(CharSequence csq,
                         int start,
                         int end)

Description copied from interface: Appendable

Append part of the given CharSequence.

If the given CharSequence is not null, this method behaves same as the following statement:

    out.append(csq.subSequence(start, end)) 

If the give CharSequence is null, the sequence is treated as String "null".

Specified by:

append in interface Appendable

Parameters:

csq - the CharSequence to be append

start - the index to spicify the start position of CharSequence to be append, must be non-negative, and not larger than the end

end - the index to speicify the end position of CharSequence to be append, must be non-negative, and not larger than the size of csq

Returns:

this Appendable

See Also:

Appendable.append(CharSequence, int, int)

read

public int read(CharBuffer target)
         throws IOException

Description copied from interface: Readable

Reads the characters into the given CharBuffer. The maximum number of characters read is CharBuffer.remaining().

Specified by:

read in interface Readable

Parameters:

target - the buffer to be filled in by the characters read

Returns:

the number of characters actually read, or -1 if this Readable reaches its end

Throws:

IOException - if some I/O operations fail

See Also:

Readable.read(CharBuffer)