This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.


java.nio
class CharBuffer

java.lang.Object extended by java.nio.Buffer extended by java.nio.CharBuffer
All Implemented Interfaces:
Appendable, CharSequence, Comparable, Readable

Most common way to construct:

CharBuffer cb = CharBuffer.allocate(1024);

Based on 49 examples


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

A character buffer.

This class defines four categories of operations upon character buffers:

Character buffers can be created either by {@link #allocate allocation}, which allocates space for the buffer's content, by {@link #wrap(char[]) wrapping} an existing character array or string into a buffer, or by creating a view of an existing byte buffer.

Like a byte buffer, a character buffer is either direct or non-direct. A character buffer created via the wrap methods of this class will be non-direct. A character 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 character buffer is direct may be determined by invoking the {@link #isDirect isDirect} method.

This class implements the {@link CharSequence} interface so that character buffers may be used wherever character sequences are accepted, for example in the regular-expression package {@link 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);


Method Summary
static CharBuffer
allocate(int capacity)

          Allocates a new character buffer.
 CharBuffer
append(char c)

          Appends the specified character to this buffer  (optional operation).
 CharBuffer
          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[]
          Returns the character array that backs this buffer  (optional operation).
 int
          Returns the offset within this buffer's backing array of the first element of the buffer  (optional operation).
abstract CharBuffer
          Creates a new, read-only character buffer that shares this buffer's content.
 char
charAt(int index)

          Reads the character at the given index relative to the current position.
abstract CharBuffer
          Compacts this buffer  (optional operation).
 int
          Compares this buffer to another.
abstract CharBuffer
          Creates a new character buffer that shares this buffer's content.
 boolean
          Tells whether or not this buffer is equal to another object.
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
          Tells whether or not this buffer is backed by an accessible character array.
 int
          Returns the current hash code of this buffer.
abstract boolean
          Tells whether or not this character buffer is direct.
 int
          Returns the length of this character buffer.
abstract ByteOrder
          Retrieves this buffer's byte order.
abstract CharBuffer
put(char c)

          Relative put method  (optional operation).
 CharBuffer
          Relative bulk 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).
 int
read(CharBuffer target)

          Attempts to read characters into the specified character buffer.
abstract CharBuffer
          Creates a new character buffer whose content is a shared subsequence of this buffer's content.
abstract CharSequence
subSequence(int start, int end)

          Creates a new character buffer that represents the specified subsequence of this buffer, relative to the current position.
 String
          Returns a string containing the characters in this buffer.
static CharBuffer
          Wraps a character sequence into a buffer.
static CharBuffer
wrap(CharSequence csq, int start, int end)

          Wraps a character sequence into a buffer.
static CharBuffer
wrap(char[] array)

          Wraps a character array into a buffer.
static CharBuffer
wrap(char[] array, int offset, int length)

          Wraps a character array into a buffer.
 
Methods inherited from class java.nio.Buffer
array, arrayOffset, capacity, clear, flip, hasArray, hasRemaining, isDirect, isReadOnly, limit, limit, mark, position, position, remaining, reset, rewind
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

allocate

public static CharBuffer allocate(int capacity)
Allocates a new character buffer.

The new buffer's position will be zero, its limit will be its capacity, and its mark will be undefined. It will have a {@link #array backing array}, and its {@link #arrayOffset array offset} will be zero.

Parameters:
capacity - The new buffer's capacity, in characters
Returns:
The new character buffer

append

public CharBuffer append(char c)
Appends the specified character 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) 

Parameters:
c - The 16-bit character to append
Returns:
This buffer

append

public 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 {@link CharBuffer#toString() toString} method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.

Parameters:
csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this character buffer.
Returns:
This buffer

append

public 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()) 

Parameters:
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
end
Returns:
This buffer

array

public final char[] array()
Returns the character 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 {@link #hasArray hasArray} method before invoking this method in order to ensure that this buffer has an accessible backing array.

Overrides:
array in class Buffer
Returns:
The array that backs this buffer

arrayOffset

public 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 {@link #hasArray hasArray} method before invoking this method in order to ensure that this buffer has an accessible backing array.

Overrides:
arrayOffset in class Buffer
Returns:
The offset within this buffer's array of the first element of the buffer

asReadOnlyBuffer

public abstract CharBuffer asReadOnlyBuffer()
Creates a new, read-only character 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 {@link #duplicate duplicate} method.

Returns:
The new, read-only character buffer

charAt

public final char charAt(int index)
Reads the character at the given index relative to the current position.

Parameters:
index - The index of the character to be read, relative to the position; must be non-negative and smaller than remaining()
Returns:
The character at index position() + index

compact

public abstract CharBuffer compact()
Compacts this buffer  (optional operation).

The characters between the buffer's current position and its limit, if any, are copied to the beginning of the buffer. That is, the character at index p = position() is copied to index zero, the character at index p + 1 is copied to index one, and so forth until the character 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 characters copied, rather than to zero, so that an invocation of this method can be followed immediately by an invocation of another relative put method.

Returns:
This buffer

compareTo

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.

A char buffer is not comparable to any other type of object.

Parameters:
that
Returns:
A negative integer, zero, or a positive integer as this buffer is less than, equal to, or greater than the given buffer

duplicate

public abstract CharBuffer duplicate()
Creates a new character 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.

Returns:
The new character buffer

equals

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,

  1. They have the same element type,

  2. They have the same number of remaining elements, and

  3. 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.

Overrides:
equals in class Object
Parameters:
ob - The object to which this buffer is to be compared
Returns:
true if, and only if, this buffer is equal to the given object

get

public abstract char get()
Relative get method. Reads the character at this buffer's current position, and then increments the position.

Returns:
The character at the buffer's current position

get

public CharBuffer get(char[] dst)
Relative bulk get method.

This method transfers characters 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) 

Parameters:
dst
Returns:
This buffer

get

public CharBuffer get(char[] dst,
                      int offset,
                      int length)
Relative bulk get method.

This method transfers characters from this buffer into the given destination array. If there are fewer characters remaining in the buffer than are required to satisfy the request, that is, if length > remaining(), then no characters are transferred and a {@link BufferUnderflowException} is thrown.

Otherwise, this method copies length characters 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 characters in this buffer and it is potentially much more efficient.

Parameters:
dst - The array into which characters are to be written
offset - The offset within the array of the first character to be written; must be non-negative and no larger than dst.length
length - The maximum number of characters to be written to the given array; must be non-negative and no larger than dst.length - offset
Returns:
This buffer

get

public abstract char get(int index)
Absolute get method. Reads the character at the given index.

Parameters:
index - The index from which the character will be read
Returns:
The character at the given index

hasArray

public final boolean hasArray()
Tells whether or not this buffer is backed by an accessible character array.

If this method returns true then the {@link #array() array} and {@link #arrayOffset() arrayOffset} methods may safely be invoked.

Overrides:
hasArray in class Buffer
Returns:
true if, and only if, this buffer is backed by an array and is not read-only

hashCode

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.

Overrides:
hashCode in class Object
Returns:
The current hash code of this buffer

isDirect

public abstract boolean isDirect()
Tells whether or not this character buffer is direct.

Overrides:
isDirect in class Buffer
Returns:
true if, and only if, this buffer is direct

length

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().

Returns:
The length of this character buffer

order

public abstract ByteOrder order()
Retrieves this buffer's byte order.

The byte order of a character buffer created by allocation or by wrapping an existing char array is the {@link ByteOrder#nativeOrder native order} of the underlying hardware. The byte order of a character buffer created as a view of a byte buffer is that of the byte buffer at the moment that the view is created.

Returns:
This buffer's byte order

put

public abstract CharBuffer put(char c)
Relative put method  (optional operation).

Writes the given character into this buffer at the current position, and then increments the position.

Parameters:
c - The character to be written
Returns:
This buffer

put

public CharBuffer put(CharBuffer src)
Relative bulk put method  (optional operation).

This method transfers the characters remaining in the given source buffer into this buffer. If there are more characters remaining in the source buffer than in this buffer, that is, if src.remaining() > remaining(), then no characters are transferred and a {@link BufferOverflowException} is thrown.

Otherwise, this method copies n = src.remaining() characters 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.

Parameters:
src - The source buffer from which characters are to be read; must not be this buffer
Returns:
This buffer

put

public final CharBuffer put(char[] src)
Relative bulk put method  (optional operation).

This method transfers the entire content of the given source character 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) 

Parameters:
src
Returns:
This buffer

put

public CharBuffer put(char[] src,
                      int offset,
                      int length)
Relative bulk put method  (optional operation).

This method transfers characters into this buffer from the given source array. If there are more characters to be copied from the array than remain in this buffer, that is, if length > remaining(), then no characters are transferred and a {@link BufferOverflowException} is thrown.

Otherwise, this method copies length characters 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.

Parameters:
src - The array from which characters are to be read
offset - The offset within the array of the first character to be read; must be non-negative and no larger than array.length
length - The number of characters to be read from the given array; must be non-negative and no larger than array.length - offset
Returns:
This buffer

put

public abstract CharBuffer put(int index,
                               char c)
Absolute put method  (optional operation).

Writes the given character into this buffer at the given index.

Parameters:
index - The index at which the character will be written
c - The character value to be written
Returns:
This buffer

put

public 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()) 

Parameters:
src
Returns:
This buffer

put

public CharBuffer put(String src,
                      int start,
                      int end)
Relative bulk put method  (optional operation).

This method transfers characters from the given string into this buffer. If there are more characters to be copied from the string than remain in this buffer, that is, if end - start > remaining(), then no characters are transferred and a {@link BufferOverflowException} is thrown.

Otherwise, this method copies n = end - start characters 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.

Parameters:
src - The string from which characters are to be read
start - The offset within the string of the first character to be read; must be non-negative and no larger than string.length()
end - The offset within the string of the last character to be read, plus one; must be non-negative and no larger than string.length()
Returns:
This buffer

read

public 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.

Parameters:
target - the buffer to read characters into
Returns:
The number of characters added to the buffer, or -1 if this source of characters is at its end
Throws:
IOException - if an I/O error occurs

slice

public abstract CharBuffer slice()
Creates a new character 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 characters 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.

Returns:
The new character buffer

subSequence

public abstract CharSequence 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.

Parameters:
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()
Returns:
The new character sequence

toString

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.

Overrides:
toString in class Object
Returns:
The specified string

wrap

public 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.

Parameters:
csq - The character sequence from which the new character buffer is to be created
Returns:
The new character buffer

wrap

public 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.

Parameters:
csq - The character sequence from which the new character buffer is to be created
start - 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.
Returns:
The new character buffer

wrap

public static CharBuffer wrap(char[] array)
Wraps a character array into a buffer.

The new buffer will be backed by the given character 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 {@link #array backing array} will be the given array, and its {@link #arrayOffset array offset} will be zero.

Parameters:
array - The array that will back this buffer
Returns:
The new character buffer

wrap

public static CharBuffer wrap(char[] array,
                              int offset,
                              int length)
Wraps a character array into a buffer.

The new buffer will be backed by the given character 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 {@link #array backing array} will be the given array, and its {@link #arrayOffset array offset} will be zero.

Parameters:
array - The array that will back the new buffer
offset - 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.
Returns:
The new character buffer


This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.
This page displays the Jadeite version of the documention, which is derived from the offical documentation that contains this copyright notice:
Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.