File	Doc	Category	Size	Date	Package
ByteBuffer.java	API Doc	phoneME MR2 API (J2ME)	45865	Wed May 02 18:00:46 BST 2007	java.nio

ByteBuffer

• java.lang.Object
  • java.nio.Buffer

Fields Summary
byte[]	array
int	arrayOffset
boolean	isDirect
boolean	disposed
Buffer	directParent Buffers created by allocateDirect have an accosiated buffer allocated in the native Heap. A user may create a slice Buffer from a direct "parent" Buffer (Buffer.slice()). The "slice" and "parent" Buffer share the same native buffer. Native buffer is released when the parent Buffer is collected. directParent is a reference from slice object to the parent. It guarantees that parent object is collected (and shared buffer is released) only after all its slice objects are collected.

Constructors Summary
ByteBuffer() Constructs a new ByteBuffer.

Methods Summary
public static java.nio.ByteBuffer	allocateDirect(int capacity) Allocates a new direct byte buffer. The new buffer's position will be zero, its limit will be its capacity, and its mark will be undefined. Whether or not it has a backing array is unspecified. For JSR 239, the mark is undefined, and no backing array will be present.. param capacity The new buffer's capacity, in bytes. return The new byte buffer. throws IllegalArgumentException If the capacity is a negative integer. if (capacity < 0) { throw new IllegalArgumentException(); } int nativeAddress = ByteBufferImpl._allocNative(capacity); ByteBuffer buf = new ByteBufferImpl(capacity, null, nativeAddress, null /*directParent is null if direct buffer is a parent itself*/); // Record the address of this buffer along with a weak // reference; if the weak reference becomes null, // we will free the native heap memory. BufferManager.newBuffer(buf, nativeAddress); return buf;
public final byte[]	array() Returns the byte 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 (isDirect) { throw new UnsupportedOperationException(); } return 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 {@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 (isDirect) { throw new UnsupportedOperationException(); } return arrayOffset;
public abstract java.nio.FloatBuffer	asFloatBuffer() Creates a view of this byte buffer as a float buffer. 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 bytes remaining in this buffer divided by four, 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 A new float buffer.
public abstract java.nio.IntBuffer	asIntBuffer() Creates a view of this byte buffer as an int buffer. 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 bytes remaining in this buffer divided by four, 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 A new int buffer.
public abstract java.nio.ShortBuffer	asShortBuffer() Creates a view of this byte buffer as a short buffer. 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 bytes remaining in this buffer divided by two, 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 A new short buffer.
public int	compareTo(java.lang.Object ob) Compares this buffer to another. Two byte 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 byte 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 byte buffer. ByteBuffer that = (ByteBuffer)ob; int n = this.position() + Math.min(this.remaining(), that.remaining()); for (int i = this.position(), j = that.position(); i < n; i++, j++) { byte v1 = this.get(i); byte 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 boolean	equals(java.lang.Object ob) Tells whether or not this buffer is equal to another object. Two byte 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 byte 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 ByteBuffer)) return false; ByteBuffer that = (ByteBuffer)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--) { byte v1 = this.get(i); byte v2 = that.get(j); if (v1 != v2) { if ((v1 != v1) && (v2 != v2)) // For float and double continue; return false; } } return true;
public java.nio.ByteBuffer	get(byte[] dst, int offset, int length) Relative bulk get method. This method transfers bytes from this buffer into the given destination array. If there are fewer bytes remaining in the buffer than are required to satisfy the request, that is, if length > remaining(), then no bytes are transferred and a {@link BufferUnderflowException} is thrown. Otherwise, this method copies length bytes 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 bytes in this buffer and it is potentially much more efficient. param dst The array into which bytes are to be written. param offset The offset within the array of the first byte to be written; must be non-negative and no larger than dst.length. param length The maximum number of bytes 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 bytes 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(); } if (isDirect) { ByteBufferImpl._getBytes(arrayOffset + position, dst, offset, length); } else { System.arraycopy(array, arrayOffset + position, dst, offset, length); } position += length; return this;
public java.nio.ByteBuffer	get(byte[] dst) Relative bulk get method. This method transfers bytes 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 bytes remaining in this buffer. return get(dst, 0, dst.length);
public abstract byte	get() Relative get method. Reads the byte at this buffer's current position, and then increments the position. return The byte at the buffer's current position. throws BufferUnderflowException If the buffer's current position is not smaller than its limit.
public abstract byte	get(int index) Absolute get method. Reads the byte at the given index. param index The index from which the byte will be read. return The byte at the given index. throws IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit.
public abstract float	getFloat() Relative get method for reading a float value. Reads the next four bytes at this buffer's current position, composing them into a float value according to the current byte order, and then increments the position by four. return The float value at the buffer's current position throws BufferUnderflowException If there are fewer than four bytes remaining in this buffer
public abstract float	getFloat(int index) Absolute get method for reading a float value. Reads four bytes at the given index, composing them into a float value according to the current byte order. param index The index from which the bytes will be read return The float value at the given index throws IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit, minus three
public abstract int	getInt() Relative get method for reading an int value. Reads the next four bytes at this buffer's current position, composing them into an int value according to the current byte order, and then increments the position by four. return The int value at the buffer's current position throws BufferUnderflowException If there are fewer than four bytes remaining in this buffer
public abstract int	getInt(int index) Absolute get method for reading an int value. Reads four bytes at the given index, composing them into a int value according to the current byte order. param index The index from which the bytes will be read return The int value at the given index throws IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit, minus three
public abstract short	getShort() Relative get method for reading a short value. Reads the next two bytes at this buffer's current position, composing them into a short value according to the current byte order, and then increments the position by two. return The short value at the buffer's current position throws BufferUnderflowException If there are fewer than two bytes remaining in this buffer
public abstract short	getShort(int index) Absolute get method for reading a short value. Reads two bytes at the given index, composing them into a short value according to the current byte order. param index The index from which the bytes will be read return The short value at the given index throws IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit, minus one
public final boolean	hasArray() Tells whether or not this buffer is backed by an accessible byte 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 !isDirect;
public int	hashCode() Returns the current hash code of this buffer. The hash code of a byte 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 boolean	isDirect() Tells whether or not this byte buffer is direct. return true if, and only if, this buffer is direct.
public java.nio.ByteBuffer	put(java.nio.ByteBuffer src) Relative bulk put method  (optional operation). This method transfers the bytes remaining in the given source buffer into this buffer. If there are more bytes remaining in the source buffer than in this buffer, that is, if src.remaining() > remaining(), then no bytes are transferred and a {@link BufferOverflowException} is thrown. Otherwise, this method copies n = src.remaining() bytes 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 bytes 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 bytes 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(); } ByteBufferImpl srci = (ByteBufferImpl)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, this.arrayOffset + this.position, length); } else if (isDirect && !srci.isDirect) { ByteBufferImpl._putBytes(this.arrayOffset + this.position, srci.array, srci.arrayOffset + srci.position, length); } else if (!isDirect && srci.isDirect) { ByteBufferImpl._getBytes(srci.arrayOffset + srci.position, this.array, this.arrayOffset + this.position, length); } else if (!isDirect && !srci.isDirect) { System.arraycopy(srci.array, srci.arrayOffset + srci.position, this.array, this.arrayOffset + this.position, length); } srci.position += length; this.position += length; return this;
public java.nio.ByteBuffer	put(byte[] src, int offset, int length) Relative bulk put method  (optional operation). This method transfers bytes into this buffer from the given source array. If there are more bytes to be copied from the array than remain in this buffer, that is, if length > remaining(), then no bytes are transferred and a {@link BufferOverflowException} is thrown. Otherwise, this method copies length bytes 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 bytes are to be read. param offset The offset within the array of the first byte to be read; must be non-negative and no larger than array.length. param length The number of bytes 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. // need revisit -- overlapping backing store? if (offset < 0 || offset > src.length || length < 0 || length > src.length - offset) { throw new IndexOutOfBoundsException(); } if (length > limit - position) { throw new BufferOverflowException(); } if (isDirect) { ByteBufferImpl._putBytes(arrayOffset + position, src, offset, length); } else { System.arraycopy(src, offset, array, arrayOffset + position, length); } position += length; return this;
public final java.nio.ByteBuffer	put(byte[] src) Relative bulk put method  (optional operation). This method transfers the entire content of the given source byte 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.ByteBuffer	put(byte b) Relative put method  (optional operation). Writes the given byte into this buffer at the current position, and then increments the position. param b The byte 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.ByteBuffer	put(int index, byte b) Absolute put method  (optional operation). Writes the given byte into this buffer at the given index. param index The index at which the byte will be written. param b The byte 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.ByteBuffer	putFloat(float value) Relative put method for writing a float value  (optional operation). Writes four bytes containing the given float value, in the current byte order, into this buffer at the current position, and then increments the position by four. param value The float value to be written return This buffer throws BufferOverflowException If there are fewer than four bytes remaining in this buffer throws ReadOnlyBufferException If this buffer is read-only
public abstract java.nio.ByteBuffer	putFloat(int index, float value) Absolute put method for writing a float value  (optional operation). Writes four bytes containing the given float value, in the current byte order, into this buffer at the given index. param index The index at which the bytes will be written param value The float value to be written return This buffer throws IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit, minus three throws ReadOnlyBufferException If this buffer is read-only
public abstract java.nio.ByteBuffer	putInt(int value) Relative put method for writing an int value  (optional operation). Writes four bytes containing the given int value, in the current byte order, into this buffer at the current position, and then increments the position by four. param value The int value to be written return This buffer throws BufferOverflowException If there are fewer than four bytes remaining in this buffer throws ReadOnlyBufferException If this buffer is read-only
public abstract java.nio.ByteBuffer	putInt(int index, int value) Absolute put method for writing an int value  (optional operation). Writes four bytes containing the given int value, in the current byte order, into this buffer at the given index. param index The index at which the bytes will be written param value The int value to be written return This buffer throws IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit, minus three throws ReadOnlyBufferException If this buffer is read-only
public abstract java.nio.ByteBuffer	putShort(short value) Relative put method for writing a short value  (optional operation). Writes two bytes containing the given short value, in the current byte order, into this buffer at the current position, and then increments the position by two. param value The short value to be written return This buffer throws BufferOverflowException If there are fewer than two bytes remaining in this buffer throws ReadOnlyBufferException If this buffer is read-only
public abstract java.nio.ByteBuffer	putShort(int index, short value) Absolute put method for writing a short value  (optional operation). Writes two bytes containing the given short value, in the current byte order, into this buffer at the given index. param index The index at which the bytes will be written param value The short value to be written return This buffer throws IndexOutOfBoundsException If index is negative or not smaller than the buffer's limit, minus one throws ReadOnlyBufferException If this buffer is read-only
public abstract java.nio.ByteBuffer	slice() Creates a new byte 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 bytes 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 byte buffer.
public java.lang.String	toString() Returns a string summarizing the state of this buffer. return A summary string return "java.nio.ByteBuffer[" + "pos=" + position() + "lim=" + limit() + "cap=" + capacity() + "]";
public static java.nio.ByteBuffer	wrap(byte[] array, int offset, int length) Wraps a byte array into a buffer. The new buffer will be backed by the the given byte 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. 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 byte 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(); } ByteBufferImpl bbi = new ByteBufferImpl(array.length, array, 0, null /*directParent is null for all nondirect buffers*/); bbi.position(offset); bbi.limit(offset + length); return bbi;
public static java.nio.ByteBuffer	wrap(byte[] array) Wraps a byte array into a buffer. The new buffer will be backed by the the given byte 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. param array The array that will back this buffer. return The new byte buffer. return wrap(array, 0, array.length);