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ShortBuffer.javaAPI DocphoneME MR2 API (J2ME)27600Wed May 02 18:00:46 BST 2007java.nio

ShortBuffer

public abstract class ShortBuffer extends Buffer implements Comparable
A short buffer.

This class is provided as part of the JSR 239 NIO Buffer building block. It is a subset of the java.nio.ShortBuffer 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 short buffers, compaction, and duplication are not supported. The following methods are omitted:

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

This class defines four categories of operations upon short buffers:

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

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

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

  • Methods for compacting, duplicating, and {@link #slice slicing} a short buffer. JSR 239 does not support compacting and duplicating buffers.

Short buffers can be created either by allocation, which allocates space for the buffer's content, by {@link #wrap(short[]) wrapping} an existing short 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 short buffer is either direct or non-direct. A short buffer created via the wrap methods of this class will be non-direct. A short 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 short 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.

Fields Summary
ByteBufferImpl
parent
short[]
array
int
arrayOffset
boolean
isDirect
boolean
disposed
Constructors Summary
ShortBuffer()
Constructs a new ShortBuffer.


              
     
Methods Summary
public final short[]array()
Returns the short 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 read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.
throws
UnsupportedOperationException If this buffer is not backed by an accessible array.

	if (array == null) {
	    throw new UnsupportedOperationException();
	}
	return array;
    
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 read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.
throws
UnsupportedOperationException If this buffer is not backed by an accessible array.

	if (array == null) {
	    throw new UnsupportedOperationException();
	}
	return arrayOffset;
    
public intcompareTo(java.lang.Object ob)
Compares this buffer to another.

Two short 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 short 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.
throws
ClassCastException If the argument is not a short buffer.

	ShortBuffer that = (ShortBuffer)ob;
	int n = this.position() + Math.min(this.remaining(), that.remaining());
	for (int i = this.position(), j = that.position(); i < n; i++, j++) {
	    short v1 = this.get(i);
	    short 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 booleanequals(java.lang.Object ob)
Tells whether or not this buffer is equal to another object.

Two short 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 short 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 ShortBuffer))
	    return false;
	ShortBuffer that = (ShortBuffer)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--) {
	    short v1 = this.get(i);
	    short v2 = that.get(j);
	    if (v1 != v2) {
		if ((v1 != v1) && (v2 != v2))	// For float and double
		    continue;
		return false;
	    }
	}
	return true;
    
public java.nio.ShortBufferget(short[] dst)
Relative bulk get method.

This method transfers shorts 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 dst.length shorts remaining in this buffer.

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

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

public abstract shortget(int index)
Absolute get method. Reads the short at the given index.

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

public java.nio.ShortBufferget(short[] dst, int offset, int length)
Relative bulk get method.

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

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

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

        if (offset < 0 || offset > dst.length ||
            length < 0 || length > dst.length - offset) {
            throw new IndexOutOfBoundsException();
        }
        if (limit - position < length) {
            throw new BufferUnderflowException();
        }

        int bytePtr = arrayOffset + (position << 1);
	if (isDirect) {
	    ByteBufferImpl._getShorts(bytePtr, dst, offset, length);
	} else if (array != null) {
	    System.arraycopy(array, arrayOffset + position,
			     dst, offset, length);
	} else {
            for (int i = 0; i < length; i++) {
                dst[offset++] = parent.getShort(bytePtr);
                bytePtr += 2;
            }
	}
	position += length;
	return this;
    
public final booleanhasArray()
Tells whether or not this buffer is backed by an accessible short 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. JSR 239 does not support read-only buffers.

	return array != null;
    
public inthashCode()
Returns the current hash code of this buffer.

The hash code of a short 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 short buffer is direct.

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

public java.nio.ShortBufferput(java.nio.ShortBuffer src)
Relative bulk put method  (optional operation).

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

Otherwise, this method copies n = src.remaining() shorts 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 shorts 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 shorts in the source buffer.
throws
IllegalArgumentException If the source buffer is this buffer.
throws
ReadOnlyBufferException If this buffer is read-only. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

        if (src == this) {
            throw new IllegalArgumentException();
        }
	
	ShortBufferImpl srci = (ShortBufferImpl)src;

	int length = srci.limit - srci.position;
        if (length > this.limit - this.position) {
            throw new BufferOverflowException();
        }
	if (isDirect && srci.isDirect) {
	    ByteBufferImpl._copyBytes(srci.arrayOffset + (srci.position << 1),
		       this.arrayOffset + (this.position << 1),
		       (length << 1));
	} else if (isDirect && !srci.isDirect) {
            if (srci.array != null) {
                ByteBufferImpl._putShorts(this.arrayOffset +
                                          (this.position << 1),
                                          srci.array,
                                          srci.arrayOffset + srci.position,
                                          length);
            } else {
                byte[] srcArray = srci.parent.array;
                int srciArrayOffset = srci.parent.arrayOffset +
                    srci.arrayOffset +
                    (srci.position << 1);
                
                ByteBufferImpl._putBytes(this.arrayOffset +
                                         (this.position << 1),
                                         srcArray,
                                         srciArrayOffset,
                                         2*length);
            }
	} else if (!isDirect && srci.isDirect) {
            if (array != null) {
                ByteBufferImpl._getShorts(srci.arrayOffset +
                                          (srci.position << 1),
                                          this.array,
                                          this.arrayOffset + this.position,
                                          length);
            } else {
                byte[] dstArray = parent.array;
                int dstArrayOffset = parent.arrayOffset +
                    arrayOffset +
                    (position << 1);
                
                ByteBufferImpl._getBytes(srci.arrayOffset +
                                         (srci.position << 1),
                                         dstArray,
                                         dstArrayOffset,
                                         2*length);
            }
	} else if (!isDirect && !srci.isDirect) {
            if (array != null && srci.array != null) {
                System.arraycopy(srci.array, srci.arrayOffset + srci.position,
                                 this.array, this.arrayOffset + this.position,
                                 length);
            } else {
                for (int i = 0; i < length; i++) {
                    put(i, srci.get(i));
                }
            }
	}
	
	srci.position += length;
	this.position += length;
	return this;
    
public java.nio.ShortBufferput(short[] src, int offset, int length)
Relative bulk put method  (optional operation).

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

Otherwise, this method copies length shorts 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 shorts are to be read.
param
offset The offset within the array of the first short to be read; must be non-negative and no larger than array.length.
param
length The number of shorts 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. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

        if (offset < 0 || offset > src.length ||
            length < 0 || length > src.length - offset) {
            throw new IndexOutOfBoundsException();
        }
        if (length > limit - position) {
            throw new BufferOverflowException();
        }

        int bytePtr = arrayOffset + (position << 1);
	if (isDirect) {
	    ByteBufferImpl._putShorts(bytePtr, src, offset, length);
	} else if (array != null) {
	    System.arraycopy(src, offset,
			     array, arrayOffset + position, length);
	} else {
            for (int i = 0; i < length; i++) {
                parent.putShort(bytePtr, src[offset++]);
                bytePtr += 2;
            }
	}
	position += length;
	return this;
    
public final java.nio.ShortBufferput(short[] src)
Relative bulk put method  (optional operation).

This method transfers the entire content of the given source short 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. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

	return put(src, 0, src.length);
    
public abstract java.nio.ShortBufferput(short s)
Relative put method  (optional operation).

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

param
s The short 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. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

public abstract java.nio.ShortBufferput(int index, short s)
Absolute put method  (optional operation).

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

param
index The index at which the short will be written.
param
s The short 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. JSR 239 does not support read-only buffer or the ReadOnlyBufferException class.

public abstract java.nio.ShortBufferslice()
Creates a new short 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 shorts 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.

return
The new short buffer.

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

return
A summary string

        return "java.nio.ShortBuffer[" +
            "pos=" + position() +
            "lim=" + limit() +
            "cap=" + capacity() +
            "]";
    
public static java.nio.ShortBufferwrap(short[] array, int offset, int length)
Wraps a short array into a buffer.

The new buffer will be backed by the given short 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 short buffer
throws
IndexOutOfBoundsException If the preconditions on the offset and length parameters do not hold

        if (offset < 0 || offset > array.length ||
            length < 0 || length > array.length - offset) {
            throw new IndexOutOfBoundsException();
        }

        ShortBufferImpl sbi =
            new ShortBufferImpl(null, array.length, array, 0, false);
        sbi.position(offset);
        sbi.limit(offset + length);
        return sbi;
    
public static java.nio.ShortBufferwrap(short[] array)
Wraps a short array into a buffer.

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

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