Class ByteBuffer

public static ByteBuffer allocateDirect(int capacity)

Allocates a new direct byte buffer.

The new buffer's position will be zero, its limit will be its capacity, its mark will be undefined, each of its elements will be initialized to zero, and its byte order will be BIG_ENDIAN. Whether or not it has a backing array is unspecified.

public static ByteBuffer allocate(int capacity)

Allocates a new byte buffer.

The new buffer's position will be zero, its limit will be its capacity, its mark will be undefined, each of its elements will be initialized to zero, and its byte order will be BIG_ENDIAN. It will have a backing array, and its array offset will be zero.

public static ByteBuffer wrap(byte[] array,
                              int offset,
                              int length)

Wraps a byte array into a buffer.

The new buffer will be backed by 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, its mark will be undefined, and its byte order will be BIG_ENDIAN. Its backing array will be the given array, and its array offset will be zero.

public static ByteBuffer wrap(byte[] array)

Wraps a byte array into a buffer.

The new buffer will be backed by 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, its mark will be undefined, and its byte order will be BIG_ENDIAN. Its backing array will be the given array, and its array offset will be zero.

public abstract 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.

The new buffer's position will be zero, its capacity and its limit will be the number of bytes remaining in this buffer, its mark will be undefined, and its byte order will be BIG_ENDIAN. 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.

public abstract ByteBuffer duplicate()

Creates a new byte 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, and its byte order will be BIG_ENDIAN. 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.

public abstract ByteBuffer asReadOnlyBuffer()

Creates a new, read-only byte 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, and its byte order will be BIG_ENDIAN.

If this buffer is itself read-only then this method behaves in exactly the same way as the duplicate method.

public abstract byte get()

public abstract 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.

public abstract byte get(int index)

public abstract ByteBuffer put(int index,
                               byte b)

Absolute put method (optional operation).

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

public 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 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.

public 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)

public ByteBuffer put(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 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.

public 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 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.

public final 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)

public final boolean hasArray()

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

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

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

public abstract ByteBuffer compact()

Compacts this buffer (optional operation).

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

Invoke this method after writing data from a buffer in case the write was incomplete. The following loop, for example, copies bytes from one channel to another via the buffer buf:

buf.clear();          // Prepare buffer for use
while (in.read(buf) >= 0 || buf.position != 0) {
    buf.flip();
    out.write(buf);
    buf.compact();    // In case of partial write
}

public abstract boolean isDirect()

public String toString()

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.

public boolean equals(Object ob)

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

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

public int compareTo(ByteBuffer that)

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. Pairs of byte elements are compared as if by invoking Byte.compare(byte,byte).

A byte buffer is not comparable to any other type of object.

public int mismatch(ByteBuffer that)

Finds and returns the relative index of the first mismatch between this buffer and a given buffer. The index is relative to the position of each buffer and will be in the range of 0 (inclusive) up to the smaller of the remaining elements in each buffer (exclusive).

If the two buffers share a common prefix then the returned index is the length of the common prefix and it follows that there is a mismatch between the two buffers at that index within the respective buffers. If one buffer is a proper prefix of the other then the returned index is the smaller of the remaining elements in each buffer, and it follows that the index is only valid for the buffer with the larger number of remaining elements. Otherwise, there is no mismatch.

public final ByteOrder order()

Retrieves this buffer's byte order.

The byte order is used when reading or writing multibyte values, and when creating buffers that are views of this byte buffer. The order of a newly-created byte buffer is always BIG_ENDIAN.

public final ByteBuffer order(ByteOrder bo)

public final int alignmentOffset(int index,
                                 int unitSize)

Returns the memory address, pointing to the byte at the given index, modulus the given unit size.

A return value greater than zero indicates the address of the byte at the index is misaligned for the unit size, and the value's quantity indicates how much the index should be rounded up or down to locate a byte at an aligned address. Otherwise, a value of 0 indicates that the address of the byte at the index is aligned for the unit size.

public final ByteBuffer alignedSlice(int unitSize)

Creates a new byte buffer whose content is a shared and aligned subsequence of this buffer's content.

The content of the new buffer will start at this buffer's current position rounded up to the index of the nearest aligned byte for the given unit size, and end at this buffer's limit rounded down to the index of the nearest aligned byte for the given unit size. If rounding results in out-of-bound values then the new buffer's capacity and limit will be zero. If rounding is within bounds the following expressions will be true for a new buffer nb and unit size unitSize:

nb.alignmentOffset(0, unitSize) == 0
 nb.alignmentOffset(nb.limit(), unitSize) == 0

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 bytes remaining in this buffer or fewer subject to alignment, its mark will be undefined, and its byte order will be BIG_ENDIAN. 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.

public abstract char getChar()

Relative get method for reading a char value.

Reads the next two bytes at this buffer's current position, composing them into a char value according to the current byte order, and then increments the position by two.

public abstract ByteBuffer putChar(char value)

Relative put method for writing a char value (optional operation).

Writes two bytes containing the given char value, in the current byte order, into this buffer at the current position, and then increments the position by two.

public abstract char getChar(int index)

Absolute get method for reading a char value.

Reads two bytes at the given index, composing them into a char value according to the current byte order.

public abstract ByteBuffer putChar(int index,
                                   char value)

Absolute put method for writing a char value (optional operation).

Writes two bytes containing the given char value, in the current byte order, into this buffer at the given index.

public abstract CharBuffer asCharBuffer()

Creates a view of this byte buffer as a char 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.

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, its mark will be undefined, and its byte order will be that of the byte buffer at the moment the view is created. 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.

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.

public abstract 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.

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.

public abstract 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.

public abstract 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.

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, its mark will be undefined, and its byte order will be that of the byte buffer at the moment the view is created. 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.

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.

public abstract 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.

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.

public abstract 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.

public abstract 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.

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, its mark will be undefined, and its byte order will be that of the byte buffer at the moment the view is created. 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.

public abstract long getLong()

Relative get method for reading a long value.

Reads the next eight bytes at this buffer's current position, composing them into a long value according to the current byte order, and then increments the position by eight.

public abstract ByteBuffer putLong(long value)

Relative put method for writing a long value (optional operation).

Writes eight bytes containing the given long value, in the current byte order, into this buffer at the current position, and then increments the position by eight.

public abstract long getLong(int index)

Absolute get method for reading a long value.

Reads eight bytes at the given index, composing them into a long value according to the current byte order.

public abstract ByteBuffer putLong(int index,
                                   long value)

Absolute put method for writing a long value (optional operation).

Writes eight bytes containing the given long value, in the current byte order, into this buffer at the given index.

public abstract LongBuffer asLongBuffer()

Creates a view of this byte buffer as a long 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.

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 eight, its mark will be undefined, and its byte order will be that of the byte buffer at the moment the view is created. 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.

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.

public abstract 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.

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.

public abstract 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.

public abstract 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.

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, its mark will be undefined, and its byte order will be that of the byte buffer at the moment the view is created. 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.

public abstract double getDouble()

Relative get method for reading a double value.

Reads the next eight bytes at this buffer's current position, composing them into a double value according to the current byte order, and then increments the position by eight.

public abstract ByteBuffer putDouble(double value)

Relative put method for writing a double value (optional operation).

Writes eight bytes containing the given double value, in the current byte order, into this buffer at the current position, and then increments the position by eight.

public abstract double getDouble(int index)

Absolute get method for reading a double value.

Reads eight bytes at the given index, composing them into a double value according to the current byte order.

public abstract ByteBuffer putDouble(int index,
                                     double value)

Absolute put method for writing a double value (optional operation).

Writes eight bytes containing the given double value, in the current byte order, into this buffer at the given index.

public abstract DoubleBuffer asDoubleBuffer()

Creates a view of this byte buffer as a double 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.

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 eight, its mark will be undefined, and its byte order will be that of the byte buffer at the moment the view is created. 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.