Module java.base

Package 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

• A method for compacting 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

Modifier and Type	Method	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.
int	mismatch(LongBuffer that)	Finds and returns the relative index of the first mismatch between this buffer and a given buffer.
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 declared in class java.nio.Buffer

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

Methods declared in 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, each of its elements will be initialized to zero, and its byte order will be the native order of the underlying hardware. 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, its mark will be undefined, and its byte order will be the native order of the underlying hardware. 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, its mark will be undefined, and its byte order will be the native order of the underlying hardware. 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, its mark will be undefined, and its byte order will be identical to that 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.

Specified by:

slice in class Buffer

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, mark values, and byte order 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.

Specified by:

duplicate in class Buffer

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, mark values, and byte order 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. If this buffer and the source buffer share the same backing array or memory, then the result will be as if the source elements were first copied to an intermediate location before being written into this buffer.

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

mismatch

public int mismatch(LongBuffer 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.

Parameters:

that - The byte buffer to be tested for a mismatch with this buffer

Returns:

The relative index of the first mismatch between this and the given buffer, otherwise -1 if no mismatch.

Since:

11

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