Class DoubleBuffer
- All Implemented Interfaces:
Comparable<DoubleBuffer>
This class defines four categories of operations upon double buffers:
Absolute and relative
get
andput
methods that read and write single doubles;Absolute and relative
bulk get
methods that transfer contiguous sequences of doubles from this buffer into an array;Absolute and relative
bulk put
methods that transfer contiguous sequences of doubles from a double array or some other double buffer into this buffer;A method for
compacting
a double buffer.
Double buffers can be created either by allocation
, which allocates space for the buffer's
content, by wrapping
an existing
double array into a buffer, or by creating a
view of an existing byte buffer.
Like a byte buffer, a double buffer is either direct or non-direct. A
double buffer created via the wrap
methods of this class will
be non-direct. A double 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 double 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.
Optional operations
Methods specified as optional operations throw a ReadOnlyBufferException when invoked on a read-only DoubleBuffer. The methods array and arrayOffset throw an UnsupportedOperationException if the DoubleBuffer is not backed by an accessible double array (irrespective of whether the DoubleBuffer is read-only).- Since:
- 1.4
-
Method Summary
Modifier and TypeMethodDescriptionstatic DoubleBuffer
allocate
(int capacity) Allocates a new double buffer.final double[]
array()
Returns the double array that backs this buffer (optional operation).final int
Returns the offset within this buffer's backing array of the first element of the buffer (optional operation).abstract DoubleBuffer
Creates a new, read-only double buffer that shares this buffer's content.final DoubleBuffer
clear()
Clears this buffer.abstract DoubleBuffer
compact()
Compacts this buffer (optional operation).int
compareTo
(DoubleBuffer that) Compares this buffer to another.abstract DoubleBuffer
Creates a new double buffer that shares this buffer's content.boolean
Tells whether or not this buffer is equal to another object.final DoubleBuffer
flip()
Flips this buffer.abstract double
get()
Relative get method.get
(double[] dst) Relative bulk get method.get
(double[] dst, int offset, int length) Relative bulk get method.abstract double
get
(int index) Absolute get method.get
(int index, double[] dst) Absolute bulk get method.get
(int index, double[] dst, int offset, int length) Absolute bulk get method.final boolean
hasArray()
Tells whether or not this buffer is backed by an accessible double array.int
hashCode()
Returns the current hash code of this buffer.abstract boolean
isDirect()
Tells whether or not this double buffer is direct.final DoubleBuffer
limit
(int newLimit) Sets this buffer's limit.final DoubleBuffer
mark()
Sets this buffer's mark at its position.int
mismatch
(DoubleBuffer 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.final DoubleBuffer
position
(int newPosition) Sets this buffer's position.abstract DoubleBuffer
put
(double d) Relative put method (optional operation).final DoubleBuffer
put
(double[] src) Relative bulk put method (optional operation).put
(double[] src, int offset, int length) Relative bulk put method (optional operation).abstract DoubleBuffer
put
(int index, double d) Absolute put method (optional operation).put
(int index, double[] src) Absolute bulk put method (optional operation).put
(int index, double[] src, int offset, int length) Absolute bulk put method (optional operation).put
(int index, DoubleBuffer src, int offset, int length) Absolute bulk put method (optional operation).put
(DoubleBuffer src) Relative bulk put method (optional operation).final DoubleBuffer
reset()
Resets this buffer's position to the previously-marked position.final DoubleBuffer
rewind()
Rewinds this buffer.abstract DoubleBuffer
slice()
Creates a new double buffer whose content is a shared subsequence of this buffer's content.abstract DoubleBuffer
slice
(int index, int length) Creates a new double buffer whose content is a shared subsequence of this buffer's content.toString()
Returns a string summarizing the state of this buffer.static DoubleBuffer
wrap
(double[] array) Wraps a double array into a buffer.static DoubleBuffer
wrap
(double[] array, int offset, int length) Wraps a double array into a buffer.Methods inherited from class java.nio.Buffer
capacity, hasRemaining, isReadOnly, limit, position, remaining
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Method Details
-
allocate
Allocates a new double 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 abacking array
, and itsarray offset
will be zero.- Parameters:
capacity
- The new buffer's capacity, in doubles- Returns:
- The new double buffer
- Throws:
IllegalArgumentException
- If thecapacity
is a negative integer
-
wrap
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 beoffset
, its limit will beoffset + length
, its mark will be undefined, and its byte order will be thenative order
of the underlying hardware. Itsbacking array
will be the given array, and itsarray offset
will be zero.- Parameters:
array
- The array that will back the new bufferoffset
- The offset of the subarray to be used; must be non-negative and no larger thanarray.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 thanarray.length - offset
. The new buffer's limit will be set tooffset + length
.- Returns:
- The new double buffer
- Throws:
IndexOutOfBoundsException
- If the preconditions on theoffset
andlength
parameters do not hold
-
wrap
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, its mark will be undefined, and its byte order will be thenative order
of the underlying hardware. Itsbacking array
will be the given array, and itsarray offset
will be zero.- Parameters:
array
- The array that will back this buffer- Returns:
- The new double buffer
-
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, 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.
-
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 position
index
in this buffer, and will containlength
elements. 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
length
, 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 classBuffer
- Parameters:
index
- The position in this buffer at which the content of the new buffer will start; must be non-negative and no larger thanlimit()
length
- The number of elements the new buffer will contain; must be non-negative and no larger thanlimit() - index
- Returns:
- The new buffer
- Throws:
IndexOutOfBoundsException
- Ifindex
is negative or greater thanlimit()
,length
is negative, orlength > limit() - index
- Since:
- 13
-
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, 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.
-
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, 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 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
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 limitReadOnlyBufferException
- 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
- Ifindex
is negative or not smaller than the buffer's limit
-
put
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 writtend
- The double value to be written- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException
- Ifindex
is negative or not smaller than the buffer's limitReadOnlyBufferException
- If this buffer is read-only
-
get
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 aBufferUnderflowException
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 bylength
.In other words, an invocation of this method of the form
src.get(dst, off, len)
has exactly the same effect as the loopfor (int i = off; i < off + len; i++) dst[i] = src.get();
- Parameters:
dst
- The array into which doubles are to be writtenoffset
- The offset within the array of the first double to be written; must be non-negative and no larger thandst.length
length
- The maximum number of doubles to be written to the given array; must be non-negative and no larger thandst.length - offset
- Returns:
- This buffer
- Throws:
BufferUnderflowException
- If there are fewer thanlength
doubles remaining in this bufferIndexOutOfBoundsException
- If the preconditions on theoffset
andlength
parameters do not hold
-
get
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 invocationsrc.get(a, 0, a.length)
- Parameters:
dst
- The destination array- Returns:
- This buffer
- Throws:
BufferUnderflowException
- If there are fewer thanlength
doubles remaining in this buffer
-
get
Absolute bulk get method.This method transfers
length
doubles from this buffer into the given array, starting at the given index in this buffer and at the given offset in the array. The position of this buffer is unchanged.An invocation of this method of the form
src.get(index, dst, offset, length)
has exactly the same effect as the following loop except that it first checks the consistency of the supplied parameters and it is potentially much more efficient:for (int i = offset, j = index; i < offset + length; i++, j++) dst[i] = src.get(j);
- Parameters:
index
- The index in this buffer from which the first double will be read; must be non-negative and less thanlimit()
dst
- The destination arrayoffset
- The offset within the array of the first double to be written; must be non-negative and less thandst.length
length
- The number of doubles to be written to the given array; must be non-negative and no larger than the smaller oflimit() - index
anddst.length - offset
- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException
- If the preconditions on theindex
,offset
, andlength
parameters do not hold- Since:
- 13
-
get
Absolute bulk get method.This method transfers doubles from this buffer into the given destination array. The position of this buffer is unchanged. An invocation of this method of the form
src.get(index, dst)
behaves in exactly the same way as the invocation:src.get(index, dst, 0, dst.length)
- Parameters:
index
- The index in this buffer from which the first double will be read; must be non-negative and less thanlimit()
dst
- The destination array- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException
- Ifindex
is negative, not smaller thanlimit()
, orlimit() - index < dst.length
- Since:
- 13
-
put
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 aBufferOverflowException
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 loopwhile (src.hasRemaining()) dst.put(src.get());
- 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 bufferIllegalArgumentException
- If the source buffer is this bufferReadOnlyBufferException
- If this buffer is read-only
-
put
Absolute bulk put method (optional operation).This method transfers
length
doubles into this buffer from the given source buffer, starting at the givenoffset
in the source buffer and the givenindex
in this buffer. The positions of both buffers are unchanged.In other words, an invocation of this method of the form
dst.put(index, src, offset, length)
has exactly the same effect as the loopfor (int i = offset, j = index; i < offset + length; i++, j++) dst.put(j, src.get(i));
- Parameters:
index
- The index in this buffer at which the first double will be written; must be non-negative and less thanlimit()
src
- The buffer from which doubles are to be readoffset
- The index within the source buffer of the first double to be read; must be non-negative and less thansrc.limit()
length
- The number of doubles to be read from the given buffer; must be non-negative and no larger than the smaller oflimit() - index
andsrc.limit() - offset
- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException
- If the preconditions on theindex
,offset
, andlength
parameters do not holdReadOnlyBufferException
- If this buffer is read-only- Since:
- 16
-
put
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 aBufferOverflowException
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 bylength
.In other words, an invocation of this method of the form
dst.put(src, off, len)
has exactly the same effect as the loopfor (int i = off; i < off + len; i++) dst.put(src[i]);
- Parameters:
src
- The array from which doubles are to be readoffset
- The offset within the array of the first double to be read; must be non-negative and no larger thansrc.length
length
- The number of doubles to be read from the given array; must be non-negative and no larger thansrc.length - offset
- Returns:
- This buffer
- Throws:
BufferOverflowException
- If there is insufficient space in this bufferIndexOutOfBoundsException
- If the preconditions on theoffset
andlength
parameters do not holdReadOnlyBufferException
- If this buffer is read-only
-
put
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 invocationdst.put(a, 0, a.length)
- Parameters:
src
- The source array- Returns:
- This buffer
- Throws:
BufferOverflowException
- If there is insufficient space in this bufferReadOnlyBufferException
- If this buffer is read-only
-
put
Absolute bulk put method (optional operation).This method transfers
length
doubles from the given array, starting at the given offset in the array and at the given index in this buffer. The position of this buffer is unchanged.An invocation of this method of the form
dst.put(index, src, offset, length)
has exactly the same effect as the following loop except that it first checks the consistency of the supplied parameters and it is potentially much more efficient:for (int i = offset, j = index; i < offset + length; i++, j++) dst.put(j, src[i]);
- Parameters:
index
- The index in this buffer at which the first double will be written; must be non-negative and less thanlimit()
src
- The array from which doubles are to be readoffset
- The offset within the array of the first double to be read; must be non-negative and less thansrc.length
length
- The number of doubles to be read from the given array; must be non-negative and no larger than the smaller oflimit() - index
andsrc.length - offset
- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException
- If the preconditions on theindex
,offset
, andlength
parameters do not holdReadOnlyBufferException
- If this buffer is read-only- Since:
- 13
-
put
Absolute bulk put method (optional operation).This method copies doubles into this buffer from the given source array. The position of this buffer is unchanged. An invocation of this method of the form
dst.put(index, src)
behaves in exactly the same way as the invocation:dst.put(index, src, 0, src.length);
- Parameters:
index
- The index in this buffer at which the first double will be written; must be non-negative and less thanlimit()
src
- The array from which doubles are to be read- Returns:
- This buffer
- Throws:
IndexOutOfBoundsException
- Ifindex
is negative, not smaller thanlimit()
, orlimit() - index < src.length
ReadOnlyBufferException
- If this buffer is read-only- Since:
- 13
-
hasArray
public final boolean hasArray()Tells whether or not this buffer is backed by an accessible double array.If this method returns
true
then thearray
andarrayOffset
methods may safely be invoked. -
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 classBuffer
- Returns:
- The array that backs this buffer
- Throws:
ReadOnlyBufferException
- If this buffer is backed by an array but is read-onlyUnsupportedOperationException
- 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 classBuffer
- 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-onlyUnsupportedOperationException
- If this buffer is not backed by an accessible array
-
position
Sets this buffer's position. If the mark is defined and larger than the new position then it is discarded. -
limit
Sets this buffer's limit. If the position is larger than the new limit then it is set to the new limit. If the mark is defined and larger than the new limit then it is discarded. -
mark
Sets this buffer's mark at its position. -
reset
Resets this buffer's position to the previously-marked position.Invoking this method neither changes nor discards the mark's value.
-
clear
Clears this buffer. The position is set to zero, the limit is set to the capacity, and the mark is discarded.Invoke this method before using a sequence of channel-read or put operations to fill this buffer. For example:
buf.clear(); // Prepare buffer for reading in.read(buf); // Read data
This method does not actually erase the data in the buffer, but it is named as if it did because it will most often be used in situations in which that might as well be the case.
-
flip
Flips this buffer. The limit is set to the current position and then the position is set to zero. If the mark is defined then it is discarded.After a sequence of channel-read or put operations, invoke this method to prepare for a sequence of channel-write or relative get operations. For example:
buf.put(magic); // Prepend header in.read(buf); // Read data into rest of buffer buf.flip(); // Flip buffer out.write(buf); // Write header + data to channel
This method is often used in conjunction with the
compact
method when transferring data from one place to another. -
rewind
Rewinds this buffer. The position is set to zero and the mark is discarded.Invoke this method before a sequence of channel-write or get operations, assuming that the limit has already been set appropriately. For example:
out.write(buf); // Write remaining data buf.rewind(); // Rewind buffer buf.get(array); // Copy data into array
-
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 indexlimit()
- 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
-
toString
-
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 atlimit()
-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.
-
equals
Tells whether or not this buffer is equal to another object.Two double 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. This method considers two double elements
a
andb
to be equal if(a == b) || (Double.isNaN(a) && Double.isNaN(b))
. The values-0.0
and+0.0
are considered to be equal, unlikeDouble.equals(Object)
.
A double buffer is not equal to any other type of object.
-
compareTo
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 invokingDouble.compare(double,double)
, except that-0.0
and0.0
are considered to be equal.Double.NaN
is considered by this method to be equal to itself and greater than all otherdouble
values (includingDouble.POSITIVE_INFINITY
).A double buffer is not comparable to any other type of object.
- Specified by:
compareTo
in interfaceComparable<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
-
mismatch
Finds and returns the relative index of the first mismatch between this buffer and a given buffer. The index is relative to theposition
of each buffer and will be in the range of 0 (inclusive) up to the smaller of theremaining
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
Retrieves this buffer's byte order.The byte order of a double buffer created by allocation or by wrapping an existing
double
array is thenative 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
-