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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:
Absolute and relative {@link #get() get} and
{@link #put(char)
put} methods that read and write
single characters;
Relative {@link #get(char[]) bulk get}
methods that transfer contiguous sequences of characters from this buffer
into an array; and
Relative {@link #put(char[]) bulk put}
methods that transfer contiguous sequences of characters from a
character array, a string, or some other character
buffer into this buffer; and
Methods for {@link #compact compacting}, {@link
#duplicate
duplicating}, and {@link #slice
slicing} a character buffer.
Character buffers can be created either by {@link #allocate
allocation 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
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
An invocation of this method of the form dst.append(c)
behaves in exactly the same way as the invocation
An invocation of this method of the form dst.append(csq)
behaves in exactly the same way as the invocation
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.
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
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.
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.
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.
}, 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.
backing array
can, for example, be replaced by the single statement
cb.put("text/");
cb.put(subtype);
cb.put("; charset=");
cb.put(enc);
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
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 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
compact()
Compacts this buffer (optional operation).
int
compareTo(CharBuffer that)
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
hasArray()
Tells whether or not this buffer is backed by an accessible character
array.
int
hashCode()
Returns the current hash code of this buffer.
abstract boolean
isDirect()
Tells whether or not this character buffer is direct.
int
length()
Returns the length of this character buffer.
abstract ByteOrder
order()
Retrieves this buffer's byte order.
abstract CharBuffer
put(char c)
Relative put method (optional operation).
CharBuffer
put(CharBuffer src)
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
Relative bulk put method (optional operation).
CharBuffer
Relative bulk put method (optional operation).
int
read(CharBuffer target)
Attempts to read characters into the specified character buffer.
abstract CharBuffer
slice()
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
toString()
Returns a string containing the characters in this 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.
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)
}, and its {@link #arrayOffset
array
offset} will be zero.
capacity
- The new buffer's capacity, in characters
append
public CharBuffer append(char c)
dst.put(c)
c
- The 16-bit character to append
append
public CharBuffer append(CharSequence csq)
dst.put(csq.toString())
csq
- The character sequence to append. If csq is
null, then the four characters "null" are
appended to this character buffer.
append
public CharBuffer append(CharSequence csq,
int start,
int end)
dst.put(csq.subSequence(start, end).toString())
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
array
public final char[] array()
arrayOffset
public final int arrayOffset()
arrayOffset
in class Buffer
asReadOnlyBuffer
public abstract CharBuffer asReadOnlyBuffer()
charAt
public final char charAt(int index)
index
- The index of the character to be read, relative to the position;
must be non-negative and smaller than remaining()public abstract CharBuffer compact()
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.
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.
A char buffer is not comparable to any other type of object.
that
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, 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 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 comparedpublic abstract char get()
public CharBuffer get(char[] dst)
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)
dst
public CharBuffer get(char[] dst, int offset, int length)
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.
dst
- The array into which characters are to be writtenoffset
- The offset within the array of the first character to be
written; must be non-negative and no larger than
dst.lengthlength
- The maximum number of characters to be written to the given
array; must be non-negative and no larger than
dst.length - offsetpublic abstract char get(int index)
index
- The index from which the character will be readpublic final boolean hasArray()
If this method returns true then the {@link #array() array} and {@link #arrayOffset() arrayOffset} methods may safely be invoked.
hasArray
in class Buffer
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
public abstract boolean isDirect()
isDirect
in class Buffer
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().
public abstract ByteOrder 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.
public abstract CharBuffer put(char c)
Writes the given character into this buffer at the current position, and then increments the position.
c
- The character to be writtenpublic CharBuffer put(CharBuffer src)
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.
src
- The source buffer from which characters are to be read;
must not be this bufferpublic final CharBuffer put(char[] src)
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)
src
public CharBuffer put(char[] src, int offset, int length)
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.
src
- The array from which characters are to be readoffset
- The offset within the array of the first character to be read;
must be non-negative and no larger than array.lengthlength
- The number of characters to be read from the given array;
must be non-negative and no larger than
array.length - offsetpublic abstract CharBuffer put(int index, char c)
Writes the given character into this buffer at the given index.
index
- The index at which the character will be writtenc
- The character value to be writtenpublic 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
public CharBuffer put(String src, int start, int end)
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.
src
- The string from which characters are to be readstart
- 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()public int read(CharBuffer target) throws IOException
target
- the buffer to read characters intoIOException
- if an I/O error occurspublic 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 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.
public abstract CharSequence 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.
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()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 class Object
public 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 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.public static CharBuffer wrap(char[] array)
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.
array
- The array that will back this bufferpublic static CharBuffer wrap(char[] array, int offset, int length)
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.
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.
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