LongBuffer (Java Platform SE 8 )
Keywords: java.nio.LongBuffer class
Date: 2015-05-24

compact1, compact2, compact3
java.nio

## Class LongBuffer

- java.lang.Object
- - java.nio.Buffer
  - - java.nio.LongBuffer

- All Implemented Interfaces:
    Comparable<LongBuffer>

      public abstract class LongBuffer
      extends Buffer
      implements Comparable<LongBuffer>

  A long buffer.

  This class defines four categories of operations upon long buffers:

  - Absolute and relative `get` and `put` methods that read and write single longs;

  - Relative `bulk get` methods that transfer contiguous sequences of longs from this buffer into an array; and

  - Relative `bulk put` methods that transfer contiguous sequences of longs from a long array or some other long buffer into this buffer; and

  - Methods for `compacting`, `duplicating`, and `slicing` a long buffer.

  Long buffers can be created either by `allocation`, which allocates space for the buffer's content, by `wrapping` an existing long array into a buffer, or by creating a view of an existing byte buffer.

  Like a byte buffer, a long buffer is either direct or non-direct. A long buffer created via the `wrap` methods of this class will be non-direct. A long 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 long buffer is direct may be determined by invoking the `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.

  Since:
    1.4

- - ### Method Summary

    All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static LongBuffer` | `allocate(int capacity)` Allocates a new long buffer.
    `long[]` | `array()` Returns the long array that backs this buffer (optional operation).
    `int` | `arrayOffset()` Returns the offset within this buffer's backing array of the first element of the buffer (optional operation).
    `abstract LongBuffer` | `asReadOnlyBuffer()` Creates a new, read-only long buffer that shares this buffer's content.
    `abstract LongBuffer` | `compact()` Compacts this buffer (optional operation).
    `int` | `compareTo(LongBuffer that)` Compares this buffer to another.
    `abstract LongBuffer` | `duplicate()` Creates a new long buffer that shares this buffer's content.
    `boolean` | `equals(Object ob)` Tells whether or not this buffer is equal to another object.
    `abstract long` | `get()` Relative get method.
    `abstract long` | `get(int index)` Absolute get method.
    `LongBuffer` | `get(long[] dst)` Relative bulk get method.
    `LongBuffer` | `get(long[] dst, int offset, int length)` Relative bulk get method.
    `boolean` | `hasArray()` Tells whether or not this buffer is backed by an accessible long array.
    `int` | `hashCode()` Returns the current hash code of this buffer.
    `abstract boolean` | `isDirect()` Tells whether or not this long buffer is direct.
    `abstract ByteOrder` | `order()` Retrieves this buffer's byte order.
    `abstract LongBuffer` | `put(int index, long l)` Absolute put method (optional operation).
    `abstract LongBuffer` | `put(long l)` Relative put method (optional operation).
    `LongBuffer` | `put(long[] src)` Relative bulk put method (optional operation).
    `LongBuffer` | `put(long[] src, int offset, int length)` Relative bulk put method (optional operation).
    `LongBuffer` | `put(LongBuffer src)` Relative bulk put method (optional operation).
    `abstract LongBuffer` | `slice()` Creates a new long buffer whose content is a shared subsequence of this buffer's content.
    `String` | `toString()` Returns a string summarizing the state of this buffer.
    `static LongBuffer` | `wrap(long[] array)` Wraps a long array into a buffer.
    `static LongBuffer` | `wrap(long[] array, int offset, int length)` Wraps a long array into a buffer.

    - ### Methods inherited from class java.nio.Buffer

      `capacity, clear, flip, hasRemaining, isReadOnly, limit, limit, mark, position, position, remaining, reset, rewind`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Method Detail

    - #### allocate

          public static LongBuffer allocate(int capacity)

      Allocates a new long 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 longs
      Returns:
        The new long buffer
      Throws:
        `IllegalArgumentException` - If the `capacity` is a negative integer

    - #### wrap

          public static LongBuffer wrap(long[] array,
                                        int offset,
                                        int length)

      Wraps a long array into a buffer.

      The new buffer will be backed by the given long 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 long buffer
      Throws:
        `IndexOutOfBoundsException` - If the preconditions on the `offset` and `length` parameters do not hold

    - #### wrap

          public static LongBuffer wrap(long[] array)

      Wraps a long array into a buffer.

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

    - #### slice

          public abstract LongBuffer slice()

      Creates a new long 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 longs 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 long buffer

    - #### duplicate

          public abstract LongBuffer duplicate()

      Creates a new long 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 long buffer

    - #### asReadOnlyBuffer

          public abstract LongBuffer asReadOnlyBuffer()

      Creates a new, read-only long 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 long buffer

    - #### get

          public abstract long get()

      Relative get method. Reads the long at this buffer's current position, and then increments the position.
      Returns:
        The long at the buffer's current position
      Throws:
        `BufferUnderflowException` - If the buffer's current position is not smaller than its limit

    - #### put

          public abstract LongBuffer put(long l)

      Relative put method (optional operation).

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

      Parameters:
        `l` - The long 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 long get(int index)

      Absolute get method. Reads the long at the given index.
      Parameters:
        `index` - The index from which the long will be read
      Returns:
        The long at the given index
      Throws:
        `IndexOutOfBoundsException` - If `index` is negative or not smaller than the buffer's limit

    - #### put

          public abstract LongBuffer put(int index,
                                         long l)

      Absolute put method (optional operation).

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

      Parameters:
        `index` - The index at which the long will be written
        `l` - The long 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 LongBuffer get(long[] dst,
                                int offset,
                                int length)

      Relative bulk get method.

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

      Otherwise, this method copies `length` longs 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 longs in this buffer and it is potentially much more efficient.
      Parameters:
        `dst` - The array into which longs are to be written
        `offset` - The offset within the array of the first long to be written; must be non-negative and no larger than `dst.length`
        `length` - The maximum number of longs 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` longs remaining in this buffer
        `IndexOutOfBoundsException` - If the preconditions on the `offset` and `length` parameters do not hold

    - #### get

          public LongBuffer get(long[] dst)

      Relative bulk get method.

      This method transfers longs 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` longs remaining in this buffer

    - #### put

          public LongBuffer put(LongBuffer src)

      Relative bulk put method (optional operation).

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

      Otherwise, this method copies n = `src.remaining()` longs 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 longs 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 longs in the source buffer
        `IllegalArgumentException` - If the source buffer is this buffer
        `ReadOnlyBufferException` - If this buffer is read-only

    - #### put

          public LongBuffer put(long[] src,
                                int offset,
                                int length)

      Relative bulk put method (optional operation).

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

      Otherwise, this method copies `length` longs 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 longs are to be read
        `offset` - The offset within the array of the first long to be read; must be non-negative and no larger than `array.length`
        `length` - The number of longs 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 LongBuffer put(long[] src)

      Relative bulk put method (optional operation).

      This method transfers the entire content of the given source long 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 long 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 long[] array()

      Returns the long 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 LongBuffer compact()

      Compacts this buffer (optional operation).

      The longs between the buffer's current position and its limit, if any, are copied to the beginning of the buffer. That is, the long at index p = `position()` is copied to index zero, the long at index p + 1 is copied to index one, and so forth until the long 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 longs 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 long 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 long 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 long 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 long 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(LongBuffer that)

      Compares this buffer to another.

      Two long 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 `long` elements are compared as if by invoking `Long.compare(long,long)`.

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

      Specified by:
        `compareTo` in interface `Comparable<LongBuffer>`
      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 long buffer created by allocation or by wrapping an existing `long` array is the `native order` of the underlying hardware. The byte order of a long 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

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