java.nio

Class FloatBuffer

java.lang.Object

java.nio.Buffer

java.nio.FloatBuffer

All Implemented Interfaces:

Comparable

public abstract class FloatBuffer
extends Buffer
implements Comparable

A float buffer.

This class is provided as part of the JSR 239 NIO Buffer building block. It is a subset of the java.nio.FloatBuffer class in Java(TM) Standard Edition version 1.4.2. Differences are noted in bold italic. The class documentation may make reference to classes that are not present in the building block.

I/O channels, marking and resetting, and read-only buffers are not supported. Allocation of non-direct float buffers, compaction, and duplication are not supported. The following methods are omitted:

• FloatBuffer allocate(int capacity)
• FloatBuffer compact()
• FloatBuffer duplicate()
• Buffer mark()
• Buffer reset()
• boolean isReadOnly()
• FloatBuffer asReadOnlyBuffer()

This class defines four categories of operations upon float buffers:

• Absolute and relative get and put methods that read and write single floats;

• Relative bulk get methods that transfer contiguous sequences of floats from this buffer into an array;

• Relative bulk put methods that transfer contiguous sequences of floats from a float array or some other float buffer into this buffer; and

• Methods for compacting, duplicating, and slicing a float buffer. JSR 239 does not support compacting and duplicating buffers.

Float buffers can be created either by allocation, which allocates space for the buffer's content, by wrapping an existing float array into a buffer, or by creating a view of an existing byte buffer. JSR 239 supports allocation of ByteBuffers only.

Like a byte buffer, a float buffer is either direct or non-direct. A float buffer created via the wrap methods of this class will be non-direct. A float 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 float 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.

Method Summary

Methods

Modifier and Type	Method and Description
float[]	array() Returns the float array that backs this buffer (optional operation).
int	arrayOffset() Returns the offset within this buffer's backing array of the first element of the buffer (optional operation).
int	compareTo(java.lang.Object ob) Compares this buffer to another.
boolean	equals(java.lang.Object ob) Tells whether or not this buffer is equal to another object.
abstract float	get() Relative get method.
FloatBuffer	get(float[] dst) Relative bulk get method.
FloatBuffer	get(float[] dst, int offset, int length) Relative bulk get method.
abstract float	get(int index) Absolute get method.
boolean	hasArray() Tells whether or not this buffer is backed by an accessible float array.
int	hashCode() Returns the current hash code of this buffer.
abstract boolean	isDirect() Tells whether or not this float buffer is direct.
abstract FloatBuffer	put(float f) Relative put method (optional operation).
FloatBuffer	put(float[] src) Relative bulk put method (optional operation).
FloatBuffer	put(float[] src, int offset, int length) Relative bulk put method (optional operation).
FloatBuffer	put(FloatBuffer src) Relative bulk put method (optional operation).
abstract FloatBuffer	put(int index, float f) Absolute put method (optional operation).
abstract FloatBuffer	slice() Creates a new float buffer whose content is a shared subsequence of this buffer's content.
java.lang.String	toString() Returns a string summarizing the state of this buffer.
static FloatBuffer	wrap(float[] array) Wraps a float array into a buffer.
static FloatBuffer	wrap(float[] array, int offset, int length) Wraps a float array into a buffer.

Methods inherited from class java.nio.Buffer

capacity, clear, flip, hasRemaining, limit, limit, position, position, remaining, rewind

Methods inherited from class java.lang.Object

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

Method Detail

wrap

public static FloatBuffer wrap(float[] array,
               int offset,
               int length)

Wraps a float array into a buffer.

The new buffer will be backed by the given float 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 float buffer

Throws:

java.lang.IndexOutOfBoundsException - If the preconditions on the offset and length parameters do not hold

wrap

public static FloatBuffer wrap(float[] array)

Wraps a float array into a buffer.

The new buffer will be backed by the given float 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 float buffer

slice

public abstract FloatBuffer slice()

Creates a new float 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. JSR 239 does not support the mark.

The new buffer's position will be zero, its capacity and its limit will be the number of floats 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. JSR 239 does not support the mark or read-only buffers.

Returns:

The new float buffer.

get

public abstract float get()

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

Returns:

The float at the buffer's current position.

Throws:

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

put

public abstract FloatBuffer put(float f)

Relative put method (optional operation).

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

Parameters:

f - The float 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. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

get

public abstract float get(int index)

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

Parameters:

index - The index from which the float will be read.

Returns:

The float at the given index.

Throws:

java.lang.IndexOutOfBoundsException - If index is negative or not smaller than the buffer's limit.

put

public abstract FloatBuffer put(int index,
              float f)

Absolute put method (optional operation).

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

Parameters:

index - The index at which the float will be written.

f - The float value to be written.

Returns:

This buffer.

Throws:

java.lang.IndexOutOfBoundsException - If index is negative or not smaller than the buffer's limit.

ReadOnlyBufferException - If this buffer is read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

get

public FloatBuffer get(float[] dst,
              int offset,
              int length)

Relative bulk get method.

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

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

Parameters:

dst - The array into which floats are to be written.

offset - The offset within the array of the first float to be written; must be non-negative and no larger than dst.length.

length - The maximum number of floats 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 dst.length floats remaining in this buffer.

java.lang.IndexOutOfBoundsException - If the preconditions on the offset and length parameters do not hold.

get

public FloatBuffer get(float[] dst)

Relative bulk get method.

This method transfers floats 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) 

Returns:

This buffer.

Throws:

BufferUnderflowException - If there are fewer than length floats remaining in this buffer.

put

public FloatBuffer put(FloatBuffer src)

Relative bulk put method (optional operation).

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

Otherwise, this method copies n = src.remaining() floats 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 floats 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 floats in the source buffer.

java.lang.IllegalArgumentException - If the source buffer is this buffer.

ReadOnlyBufferException - If this buffer is read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

put

public FloatBuffer put(float[] src,
              int offset,
              int length)

Relative bulk put method (optional operation).

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

Otherwise, this method copies length floats 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 floats are to be read.

offset - The offset within the array of the first float to be read; must be non-negative and no larger than array.length.

length - The number of floats 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.

java.lang.IndexOutOfBoundsException - If the preconditions on the offset and length parameters do not hold.

ReadOnlyBufferException - If this buffer is read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

put

public final FloatBuffer put(float[] src)

Relative bulk put method (optional operation).

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

Returns:

This buffer.

Throws:

BufferOverflowException - If there is insufficient space in this buffer.

ReadOnlyBufferException - If this buffer is read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

hasArray

public final boolean hasArray()

Tells whether or not this buffer is backed by an accessible float 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. JSR 239 does not support read-only buffers.

array

public final float[] array()

Returns the float 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 read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

UnsupportedOperationException - If this buffer is not backed by an accessible array.

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 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 read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

UnsupportedOperationException - If this buffer is not backed by an accessible array.

isDirect

public abstract boolean isDirect()

Tells whether or not this float buffer is direct.

Returns:

true if, and only if, this buffer is direct.

toString

public java.lang.String toString()

Returns a string summarizing the state of this buffer.

Overrides:

toString in class java.lang.Object

Returns:

A summary string

hashCode

public int hashCode()

Returns the current hash code of this buffer.

The hash code of a float 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 java.lang.Object

Returns:

The current hash code of this buffer

equals

public boolean equals(java.lang.Object ob)

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

Two float 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 float buffer is not equal to any other type of object.

Overrides:

equals in class java.lang.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.

compareTo

public int compareTo(java.lang.Object ob)

Compares this buffer to another.

Two float 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 float buffer is not comparable to any other type of object.

Specified by:

compareTo in interface Comparable

Parameters:

ob - the Object to be compared.

Returns:

A negative integer, zero, or a positive integer as this buffer is less than, equal to, or greater than the given buffer.

Throws:

java.lang.ClassCastException - If the argument is not a float buffer.