DoubleBuffer

public abstract class DoubleBuffer extends Buffer
implements Comparable<DoubleBuffer>

A double buffer.

This class defines four categories of operations upon double buffers:

Absolute and relative get and put methods that read and write single doubles;
Relative bulk get methods that transfer contiguous sequences of doubles from this buffer into an array; and
Relative bulk put methods that transfer contiguous sequences of doubles from a double array or some other double buffer into this buffer; and
Methods for compacting, duplicating, and slicing a double buffer.

Double buffers can be created either by allocation, which allocates space for the buffer's content, by wrapping an existing double array into a buffer, or by creating a view of an existing byte buffer.

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

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.

Public Method Summary

static DoubleBuffer	allocate(int capacity) Allocates a new double buffer.
final double[]	array() Returns the double array that backs this buffer (optional operation).
final int	arrayOffset() Returns the offset within this buffer's backing array of the first element of the buffer (optional operation).
abstract DoubleBuffer	asReadOnlyBuffer() Creates a new, read-only double buffer that shares this buffer's content.
Buffer	clear() Clears this buffer.
abstract DoubleBuffer	compact() Compacts this buffer (optional operation).
int	compareTo(DoubleBuffer that) Compares this buffer to another.
abstract DoubleBuffer	duplicate() Creates a new double buffer that shares this buffer's content.
boolean	equals(Object ob) Tells whether or not this buffer is equal to another object.
Buffer	flip() Flips this buffer.
abstract double	get() Relative get method.
DoubleBuffer	get(double[] dst, int offset, int length) Relative bulk get method.
DoubleBuffer	get(double[] dst) Relative bulk get method.
abstract double	get(int index) Absolute get method.
final boolean	hasArray() Tells whether or not this buffer is backed by an accessible double array.
int	hashCode() Returns the current hash code of this buffer.
abstract boolean	isDirect() Tells whether or not this double buffer is direct.
Buffer	limit(int newLimit) Sets this buffer's limit.
Buffer	mark() Sets this buffer's mark at its position.
abstract ByteOrder	order() Retrieves this buffer's byte order.
Buffer	position(int newPosition) Sets this buffer's position.
DoubleBuffer	put(DoubleBuffer src) Relative bulk put method (optional operation).
DoubleBuffer	put(double[] src, int offset, int length) Relative bulk put method (optional operation).
abstract DoubleBuffer	put(double d) Relative put method (optional operation).
final DoubleBuffer	put(double[] src) Relative bulk put method (optional operation).
abstract DoubleBuffer	put(int index, double d) Absolute put method (optional operation).
Buffer	reset() Resets this buffer's position to the previously-marked position.
Buffer	rewind() Rewinds this buffer.
abstract DoubleBuffer	slice() Creates a new double buffer whose content is a shared subsequence of this buffer's content.
String	toString() Returns a string summarizing the state of this buffer.
static DoubleBuffer	wrap(double[] array) Wraps a double array into a buffer.
static DoubleBuffer	wrap(double[] array, int offset, int length) Wraps a double array into a buffer.

Inherited Method Summary

From class java.nio.Buffer

abstract Object	array() Returns the array that backs this buffer (optional operation).
abstract int	arrayOffset() Returns the offset within this buffer's backing array of the first element of the buffer (optional operation).
final int	capacity() Returns this buffer's capacity.
Buffer	clear() Clears this buffer.
Buffer	flip() Flips this buffer.
abstract boolean	hasArray() Tells whether or not this buffer is backed by an accessible array.
final boolean	hasRemaining() Tells whether there are any elements between the current position and the limit.
abstract boolean	isDirect() Tells whether or not this buffer is direct.
abstract boolean	isReadOnly() Tells whether or not this buffer is read-only.
final int	limit() Returns this buffer's limit.
Buffer	limit(int newLimit) Sets this buffer's limit.
Buffer	mark() Sets this buffer's mark at its position.
Buffer	position(int newPosition) Sets this buffer's position.
final int	position() Returns this buffer's position.
final int	remaining() Returns the number of elements between the current position and the limit.
Buffer	reset() Resets this buffer's position to the previously-marked position.
Buffer	rewind() Rewinds this buffer.

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.

From interface java.lang.Comparable

abstract int

compareTo(DoubleBuffer o)

Compares this object with the specified object for order.

Public Methods

public static DoubleBuffer allocate (int capacity)

Allocates a new double 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.

Parameters

capacity	The new buffer's capacity, in doubles

Returns

The new double buffer

Throws

IllegalArgumentException	If the `capacity` is a negative integer

public final double[] array ()

Returns the double 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.

Returns

The array that backs this buffer

Throws

ReadOnlyBufferException	If this buffer is backed by an array but is read-only
UnsupportedOperationException	If this buffer is not backed by an accessible array

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 hasArray method before invoking this method in order to ensure that this buffer has an accessible backing array.

Returns

The offset within this buffer's array of the first element of the buffer

Throws

ReadOnlyBufferException	If this buffer is backed by an array but is read-only
UnsupportedOperationException	If this buffer is not backed by an accessible array

public abstract DoubleBuffer asReadOnlyBuffer ()

Creates a new, read-only double 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.

Returns

The new, read-only double buffer

public Buffer clear ()

Clears this buffer. The position is set to zero, the limit is set to the capacity, and the mark is discarded.

Invoke this method before using a sequence of channel-read or put operations to fill this buffer. For example:

 buf.clear();     // Prepare buffer for reading
 in.read(buf);    // Read data

This method does not actually erase the data in the buffer, but it is named as if it did because it will most often be used in situations in which that might as well be the case.

Returns

This buffer

public abstract DoubleBuffer compact ()

Compacts this buffer (optional operation).

The doubles between the buffer's current position and its limit, if any, are copied to the beginning of the buffer. That is, the double at index p = position() is copied to index zero, the double at index p + 1 is copied to index one, and so forth until the double 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 doubles 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

Throws

ReadOnlyBufferException	If this buffer is read-only

public int compareTo (DoubleBuffer that)

Compares this buffer to another.

Two double 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 double elements are compared as if by invoking Double.compare(double, double), except that -0.0 and 0.0 are considered to be equal. Double.NaN is considered by this method to be equal to itself and greater than all other double values (including Double.POSITIVE_INFINITY).

A double 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

public abstract DoubleBuffer duplicate ()

Creates a new double 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 double buffer

public boolean equals (Object ob)

Tells whether or not this buffer is equal to another object.

Two double 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. This method considers two double elements a and b to be equal if (a == b) || (Double.isNaN(a) && Double.isNaN(b)). The values -0.0 and +0.0 are considered to be equal, unlike Double.equals(Object).

A double buffer is not equal to any other type of 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

public Buffer flip ()

Flips this buffer. The limit is set to the current position and then the position is set to zero. If the mark is defined then it is discarded.

After a sequence of channel-read or put operations, invoke this method to prepare for a sequence of channel-write or relative get operations. For example:

 buf.put(magic);    // Prepend header
 in.read(buf);      // Read data into rest of buffer
 buf.flip();        // Flip buffer
 out.write(buf);    // Write header + data to channel

This method is often used in conjunction with the compact method when transferring data from one place to another.

Returns

This buffer

public abstract double get ()

Relative get method. Reads the double at this buffer's current position, and then increments the position.

Returns

The double at the buffer's current position

Throws

BufferUnderflowException	If the buffer's current position is not smaller than its limit

public DoubleBuffer get (double[] dst, int offset, int length)

Relative bulk get method.

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

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

Parameters

dst	The array into which doubles are to be written
offset	The offset within the array of the first double to be written; must be non-negative and no larger than `dst.length`
length	The maximum number of doubles to be written to the given array; must be non-negative and no larger than `dst.length - offset`

Returns

This buffer

Throws

BufferUnderflowException	If there are fewer than `length` doubles remaining in this buffer
IndexOutOfBoundsException	If the preconditions on the `offset` and `length` parameters do not hold

public DoubleBuffer get (double[] dst)

Relative bulk get method.

This method transfers doubles 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	The destination array

Returns

This buffer

Throws

BufferUnderflowException	If there are fewer than `length` doubles remaining in this buffer

public abstract double get (int index)

Absolute get method. Reads the double at the given index.

Parameters

index	The index from which the double will be read

Returns

The double at the given index

Throws

IndexOutOfBoundsException	If `index` is negative or not smaller than the buffer's limit

public final boolean hasArray ()

Tells whether or not this buffer is backed by an accessible double array.

If this method returns true then the array and arrayOffset methods may safely be invoked.

Returns

true if, and only if, this buffer is backed by an array and is not read-only

public int hashCode ()

Returns the current hash code of this buffer.

The hash code of a double 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.

Returns

The current hash code of this buffer

public abstract boolean isDirect ()

Tells whether or not this double buffer is direct.

Returns

true if, and only if, this buffer is direct

public Buffer limit (int newLimit)

Sets this buffer's limit. If the position is larger than the new limit then it is set to the new limit. If the mark is defined and larger than the new limit then it is discarded.

Parameters

newLimit	The new limit value; must be non-negative and no larger than this buffer's capacity

Returns

This buffer

public Buffer mark ()

Sets this buffer's mark at its position.

Returns

This buffer

public abstract ByteOrder order ()

Retrieves this buffer's byte order.

The byte order of a double buffer created by allocation or by wrapping an existing double array is the native order of the underlying hardware. The byte order of a double 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

public Buffer position (int newPosition)

Sets this buffer's position. If the mark is defined and larger than the new position then it is discarded.

Parameters

newPosition	The new position value; must be non-negative and no larger than the current limit

Returns

This buffer

public DoubleBuffer put (DoubleBuffer src)

Relative bulk put method (optional operation).

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

Otherwise, this method copies n = src.remaining() doubles 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 doubles are to be read; must not be this buffer

Returns

This buffer

Throws

BufferOverflowException	If there is insufficient space in this buffer for the remaining doubles in the source buffer
IllegalArgumentException	If the source buffer is this buffer
ReadOnlyBufferException	If this buffer is read-only

public DoubleBuffer put (double[] src, int offset, int length)

Relative bulk put method (optional operation).

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

Otherwise, this method copies length doubles 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 doubles are to be read
offset	The offset within the array of the first double to be read; must be non-negative and no larger than `array.length`
length	The number of doubles to be read from the given array; must be non-negative and no larger than `array.length - offset`

Returns

This buffer

Throws

BufferOverflowException	If there is insufficient space in this buffer
IndexOutOfBoundsException	If the preconditions on the `offset` and `length` parameters do not hold
ReadOnlyBufferException	If this buffer is read-only

public abstract DoubleBuffer put (double d)

Relative put method (optional operation).

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

Parameters

d	The double to be written

Returns

This buffer

Throws

BufferOverflowException	If this buffer's current position is not smaller than its limit
ReadOnlyBufferException	If this buffer is read-only

public final DoubleBuffer put (double[] src)

Relative bulk put method (optional operation).

This method transfers the entire content of the given source double 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	The source array

Returns

This buffer

Throws

BufferOverflowException	If there is insufficient space in this buffer
ReadOnlyBufferException	If this buffer is read-only

public abstract DoubleBuffer put (int index, double d)

Absolute put method (optional operation).

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

Parameters

index	The index at which the double will be written
d	The double value to be written

Returns

This buffer

Throws

IndexOutOfBoundsException	If `index` is negative or not smaller than the buffer's limit
ReadOnlyBufferException	If this buffer is read-only

public Buffer reset ()

Resets this buffer's position to the previously-marked position.

Invoking this method neither changes nor discards the mark's value.

Returns

This buffer

public Buffer rewind ()

Rewinds this buffer. The position is set to zero and the mark is discarded.

Invoke this method before a sequence of channel-write or get operations, assuming that the limit has already been set appropriately. For example:

 out.write(buf);    // Write remaining data
 buf.rewind();      // Rewind buffer
 buf.get(array);    // Copy data into array

Returns

This buffer

public abstract DoubleBuffer slice ()

Creates a new double 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 doubles 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 double buffer

public String toString ()

Returns a string summarizing the state of this buffer.

Returns

A summary string

public static DoubleBuffer wrap (double[] array)

Wraps a double array into a buffer.

The new buffer will be backed by the given double 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.

Parameters

array	The array that will back this buffer

Returns

The new double buffer

public static DoubleBuffer wrap (double[] array, int offset, int length)

Wraps a double array into a buffer.

The new buffer will be backed by the given double 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.

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 double buffer

Throws

IndexOutOfBoundsException	If the preconditions on the `offset` and `length` parameters do not hold