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FloatBuffer.javaAPI DocJava SE 6 API28723Tue Jun 10 01:17:44 BST 2008java.nio

FloatBuffer

public abstract class FloatBuffer extends Buffer implements Comparable
A float buffer.

This class defines four categories of operations upon float buffers:

  • Absolute and relative {@link #get() get} and {@link #put(float) put} methods that read and write single floats;

  • Relative {@link #get(float[]) bulk get} methods that transfer contiguous sequences of floats from this buffer into an array; and

  • Relative {@link #put(float[]) bulk put} methods that transfer contiguous sequences of floats from a float array or some other float buffer into this buffer; and

  • Methods for {@link #compact compacting}, {@link #duplicate duplicating}, and {@link #slice slicing} a float buffer.

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

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 {@link #isDirect 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.

author
Mark Reinhold
author
JSR-51 Expert Group
version
1.62, 06/07/10
since
1.4

Fields Summary
final float[]
hb
final int
offset
boolean
isReadOnly
Constructors Summary
FloatBuffer(int mark, int pos, int lim, int cap, float[] hb, int offset)

	super(mark, pos, lim, cap);
	this.hb = hb;
	this.offset = offset;
    
FloatBuffer(int mark, int pos, int lim, int cap)

	// package-private
	this(mark, pos, lim, cap, null, 0);
    
Methods Summary
public static java.nio.FloatBufferallocate(int capacity)
Allocates a new float 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.

param
capacity The new buffer's capacity, in floats
return
The new float buffer
throws
IllegalArgumentException If the capacity is a negative integer

	if (capacity < 0)
	    throw new IllegalArgumentException();
	return new HeapFloatBuffer(capacity, capacity);
    
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 {@link #hasArray hasArray} method before invoking this method in order to ensure that this buffer has an accessible backing array.

return
The array that backs this buffer
throws
ReadOnlyBufferException If this buffer is backed by an array but is read-only
throws
UnsupportedOperationException If this buffer is not backed by an accessible array

	if (hb == null)
	    throw new UnsupportedOperationException();
	if (isReadOnly)
	    throw new ReadOnlyBufferException();
	return hb;
    
public final intarrayOffset()
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.

return
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
throws
UnsupportedOperationException If this buffer is not backed by an accessible array

	if (hb == null)
	    throw new UnsupportedOperationException();
	if (isReadOnly)
	    throw new ReadOnlyBufferException();
	return offset;
    
public abstract java.nio.FloatBufferasReadOnlyBuffer()
Creates a new, read-only float 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.

return
The new, read-only float buffer

public abstract java.nio.FloatBuffercompact()
Compacts this buffer  (optional operation).

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

return
This buffer
throws
ReadOnlyBufferException If this buffer is read-only

public intcompareTo(java.nio.FloatBuffer that)
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.

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

	int n = this.position() + Math.min(this.remaining(), that.remaining());
	for (int i = this.position(), j = that.position(); i < n; i++, j++) {
	    float v1 = this.get(i);
	    float v2 = that.get(j);
	    if (v1 == v2)
		continue;
	    if ((v1 != v1) && (v2 != v2)) 	// For float and double
		continue;
	    if (v1 < v2)
		return -1;
	    return +1;
	}
	return this.remaining() - that.remaining();
    
public abstract java.nio.FloatBufferduplicate()
Creates a new float 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.

return
The new float buffer

public booleanequals(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.

param
ob The object to which this buffer is to be compared
return
true if, and only if, this buffer is equal to the given object

	if (!(ob instanceof FloatBuffer))
	    return false;
	FloatBuffer that = (FloatBuffer)ob;
	if (this.remaining() != that.remaining())
	    return false;
	int p = this.position();
	for (int i = this.limit() - 1, j = that.limit() - 1; i >= p; i--, j--) {
	    float v1 = this.get(i);
	    float v2 = that.get(j);
	    if (v1 != v2) {
		if ((v1 != v1) && (v2 != v2))	// For float and double
		    continue;
		return false;
	    }
	}
	return true;
    
public abstract floatget(int index)
Absolute get method. Reads the float at the given index.

param
index The index from which the float will be read
return
The float at the given index
throws
IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit

public java.nio.FloatBufferget(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 {@link 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.

param
dst The array into which floats are to be written
param
offset The offset within the array of the first float to be written; must be non-negative and no larger than dst.length
param
length The maximum number of floats to be written to the given array; must be non-negative and no larger than dst.length - offset
return
This buffer
throws
BufferUnderflowException If there are fewer than length floats remaining in this buffer
throws
IndexOutOfBoundsException If the preconditions on the offset and length parameters do not hold

	checkBounds(offset, length, dst.length);
	if (length > remaining())
	    throw new BufferUnderflowException();
	int end = offset + length;
	for (int i = offset; i < end; i++)
	    dst[i] = get();
	return this;
    
public java.nio.FloatBufferget(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) 

return
This buffer
throws
BufferUnderflowException If there are fewer than length floats remaining in this buffer

	return get(dst, 0, dst.length);
    
public abstract floatget()
Relative get method. Reads the float at this buffer's current position, and then increments the position.

return
The float at the buffer's current position
throws
BufferUnderflowException If the buffer's current position is not smaller than its limit

public final booleanhasArray()
Tells whether or not this buffer is backed by an accessible float array.

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

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

	return (hb != null) && !isReadOnly;
    
public inthashCode()
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.

return
The current hash code of this buffer

	int h = 1;
	int p = position();
	for (int i = limit() - 1; i >= p; i--)
	    h = 31 * h + (int)get(i);
	return h;
    
public abstract booleanisDirect()
Tells whether or not this float buffer is direct.

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

public abstract java.nio.ByteOrderorder()
Retrieves this buffer's byte order.

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

return
This buffer's byte order

public abstract java.nio.FloatBufferput(float f)
Relative put method  (optional operation).

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

param
f The float to be written
return
This buffer
throws
BufferOverflowException If this buffer's current position is not smaller than its limit
throws
ReadOnlyBufferException If this buffer is read-only

public abstract java.nio.FloatBufferput(int index, float f)
Absolute put method  (optional operation).

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

param
index The index at which the float will be written
param
f The float value to be written
return
This buffer
throws
IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit
throws
ReadOnlyBufferException If this buffer is read-only

public java.nio.FloatBufferput(java.nio.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 {@link 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.

param
src The source buffer from which floats are to be read; must not be this buffer
return
This buffer
throws
BufferOverflowException If there is insufficient space in this buffer for the remaining floats in the source buffer
throws
IllegalArgumentException If the source buffer is this buffer
throws
ReadOnlyBufferException If this buffer is read-only

	if (src == this)
	    throw new IllegalArgumentException();
	int n = src.remaining();
	if (n > remaining())
	    throw new BufferOverflowException();
	for (int i = 0; i < n; i++)
	    put(src.get());
	return this;
    
public java.nio.FloatBufferput(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 {@link 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.

param
src The array from which floats are to be read
param
offset The offset within the array of the first float to be read; must be non-negative and no larger than array.length
param
length The number of floats to be read from the given array; must be non-negative and no larger than array.length - offset
return
This buffer
throws
BufferOverflowException If there is insufficient space in this buffer
throws
IndexOutOfBoundsException If the preconditions on the offset and length parameters do not hold
throws
ReadOnlyBufferException If this buffer is read-only

	checkBounds(offset, length, src.length);
	if (length > remaining())
	    throw new BufferOverflowException();
	int end = offset + length;
	for (int i = offset; i < end; i++)
	    this.put(src[i]);
	return this;
    
public final java.nio.FloatBufferput(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) 

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

	return put(src, 0, src.length);
    
public abstract java.nio.FloatBufferslice()
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.

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.

return
The new float buffer

public java.lang.StringtoString()
Returns a string summarizing the state of this buffer.

return
A summary string

	StringBuffer sb = new StringBuffer();
	sb.append(getClass().getName());
	sb.append("[pos=");
	sb.append(position());
	sb.append(" lim=");
	sb.append(limit());
	sb.append(" cap=");
	sb.append(capacity());
	sb.append("]");
	return sb.toString();
    
public static java.nio.FloatBufferwrap(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 {@link #array backing array} will be the given array, and its {@link #arrayOffset array offset} will be zero.

param
array The array that will back the new buffer
param
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.
param
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.
return
The new float buffer
throws
IndexOutOfBoundsException If the preconditions on the offset and length parameters do not hold

	try {
	    return new HeapFloatBuffer(array, offset, length);
	} catch (IllegalArgumentException x) {
	    throw new IndexOutOfBoundsException();
	}
    
public static java.nio.FloatBufferwrap(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 {@link #array backing array} will be the given array, and its {@link #arrayOffset array offset} will be zero.

param
array The array that will back this buffer
return
The new float buffer

	return wrap(array, 0, array.length);