Package java.nio

Class MappedByteBuffer

java.lang.Object

java.nio.Buffer

java.nio.ByteBuffer

java.nio.MappedByteBuffer

All Implemented Interfaces:

Comparable<ByteBuffer>

public abstract class MappedByteBuffer
extends ByteBuffer

MappedByteBuffer is a special kind of direct byte buffer which maps a region of file to memory.

MappedByteBuffer can be created by calling FileChannel.map. Once created, the mapping between the byte buffer and the file region remains valid until the byte buffer is garbage collected.

All or part of a MappedByteBuffer's content may change or become inaccessible at any time, since the mapped file region can be modified by another thread or process at any time. If this happens, the behavior of the MappedByteBuffer is undefined.

Method Summary

Modifier and Type	Method	Description
MappedByteBuffer	force()	Flushes changes made to the in-memory buffer back to the mapped file.
boolean	isLoaded()	Returns true if there is a high probability that every page of this buffer is currently loaded in RAM, meaning that accesses will not cause a page fault.
MappedByteBuffer	load()	Attempts to load every page of this buffer into RAM.

Methods inherited from class java.nio.ByteBuffer

allocate, allocateDirect, array, arrayOffset, asCharBuffer, asDoubleBuffer, asFloatBuffer, asIntBuffer, asLongBuffer, asReadOnlyBuffer, asShortBuffer, compact, compareTo, duplicate, equals, get, get, get, get, getChar, getChar, getDouble, getDouble, getFloat, getFloat, getInt, getInt, getLong, getLong, getShort, getShort, hasArray, hashCode, isDirect, order, order, put, put, put, put, put, putChar, putChar, putDouble, putDouble, putFloat, putFloat, putInt, putInt, putLong, putLong, putShort, putShort, slice, wrap, wrap

Methods inherited from class java.nio.Buffer

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

Methods inherited from class java.lang.Object

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

Method Details

isLoaded

public final boolean isLoaded()

Returns true if there is a high probability that every page of this buffer is currently loaded in RAM, meaning that accesses will not cause a page fault. It is impossible to give a strong guarantee since this is only a snapshot of a dynamic situation.

load

public final MappedByteBuffer load()

Attempts to load every page of this buffer into RAM. See isLoaded().

Returns:

this buffer.

force

public final MappedByteBuffer force()

Flushes changes made to the in-memory buffer back to the mapped file. Unless you call this, changes may not be written back until the finalizer runs. This method waits for the write to complete before returning.

Returns:

this buffer.