Java compact1, compact2, compact3 java.nio Class DoubleBuffer（JDK8）

Method Detail

• allocate

  public static DoubleBuffer allocate(int capacity)

  Allocates a new double buffer.

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

  Parameters:

  capacity - The new buffer's capacity, in doubles

  Returns:

  The new double buffer

  Throws:

  IllegalArgumentException - If the capacity is a negative integer

• wrap

  public static DoubleBuffer wrap(double[] array,
                                  int offset,
                                  int length)

  Wraps a double array into a buffer.

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

  Throws:

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

• wrap

  public static DoubleBuffer wrap(double[] array)

  Wraps a double array into a buffer.

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

• slice

  public abstract DoubleBuffer slice()

  Creates a new double 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 doubles 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.

  Returns:

  The new double buffer

• duplicate

  public abstract DoubleBuffer duplicate()

  Creates a new double 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.

  Returns:

  The new double buffer

• asReadOnlyBuffer

  public abstract DoubleBuffer asReadOnlyBuffer()

  Creates a new, read-only double 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 duplicate method.

  Returns:

  The new, read-only double buffer

• get

  public abstract double get()

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

  Returns:

  The double at the buffer's current position

  Throws:

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

• put

  public abstract DoubleBuffer put(double d)

  Relative put method  (optional operation).

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

  Parameters:

  d - The double 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

• get

  public abstract double get(int index)

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

  Parameters:

  index - The index from which the double will be read

  Returns:

  The double at the given index

  Throws:

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

• put

  public abstract DoubleBuffer put(int index,
                                   double d)

  Absolute put method  (optional operation).

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

  Parameters:

  index - The index at which the double will be written

  d - The double value to be written

  Returns:

  This buffer

  Throws:

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

  ReadOnlyBufferException - If this buffer is read-only

• get

  public DoubleBuffer get(double[] dst,
                          int offset,
                          int length)

  Relative bulk get method.

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

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

  Parameters:

  dst - The array into which doubles are to be written

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

  length - The maximum number of doubles 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 length doubles remaining in this buffer

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

• get

  public DoubleBuffer get(double[] dst)

  Relative bulk get method.

  This method transfers doubles 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) 

  Parameters:

  dst - The destination array

  Returns:

  This buffer

  Throws:

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

• put

  public DoubleBuffer put(DoubleBuffer src)

  Relative bulk put method  (optional operation).

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

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

  IllegalArgumentException - If the source buffer is this buffer

  ReadOnlyBufferException - If this buffer is read-only

• put

  public DoubleBuffer put(double[] src,
                          int offset,
                          int length)

  Relative bulk put method  (optional operation).

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

  Otherwise, this method copies length doubles 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 doubles are to be read

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

  length - The number of doubles 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

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

  ReadOnlyBufferException - If this buffer is read-only

• put

  public final DoubleBuffer put(double[] src)

  Relative bulk put method  (optional operation).

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

  Parameters:

  src - The source array

  Returns:

  This buffer

  Throws:

  BufferOverflowException - If there is insufficient space in this buffer

  ReadOnlyBufferException - If this buffer is read-only

• hasArray

  public final boolean hasArray()

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

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

  Specified by:

  hasArray in class Buffer

  Returns:

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

• array

  public final double[] array()

  Returns the double 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.

  Specified by:

  array in class Buffer

  Returns:

  The array that backs this buffer

  Throws:

  ReadOnlyBufferException - If this buffer is backed by an array but is read-only

  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.

  Specified by:

  arrayOffset in class Buffer

  Returns:

  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

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

• compact

  public abstract DoubleBuffer compact()

  Compacts this buffer  (optional operation).

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

  Returns:

  This buffer

  Throws:

  ReadOnlyBufferException - If this buffer is read-only

• isDirect

  public abstract boolean isDirect()

  Tells whether or not this double buffer is direct.

  Specified by:

  isDirect in class Buffer

  Returns:

  true if, and only if, this buffer is direct

• toString

  public String toString()

  Returns a string summarizing the state of this buffer.

  Overrides:

  toString in class Object

  Returns:

  A summary string

• hashCode

  public int hashCode()

  Returns the current hash code of this buffer.

  The hash code of a double 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 Object

  Returns:

  The current hash code of this buffer

  See Also:

  Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)

• equals

  public boolean equals(Object ob)

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

  Two double 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. This method considers two double elements a and b to be equal if (a == b) || (Double.isNaN(a) && Double.isNaN(b)). The values -0.0 and +0.0 are considered to be equal, unlike Double.equals(Object).

  A double buffer is not equal to any other type of object.

  Overrides:

  equals in class 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

  See Also:

  Object.hashCode(), HashMap

• compareTo

  public int compareTo(DoubleBuffer that)

  Compares this buffer to another.

  Two double 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 double elements are compared as if by invoking Double.compare(double,double), except that -0.0 and 0.0 are considered to be equal. Double.NaN is considered by this method to be equal to itself and greater than all other double values (including Double.POSITIVE_INFINITY).

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

  Specified by:

  compareTo in interface Comparable<DoubleBuffer>

  Parameters:

  that - 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

• order

  public abstract ByteOrder order()

  Retrieves this buffer's byte order.

  The byte order of a double buffer created by allocation or by wrapping an existing double array is the native order of the underlying hardware. The byte order of a double buffer created as a view of a byte buffer is that of the byte buffer at the moment that the view is created.

  Returns:

  This buffer's byte order