在我们与Sean Patrick Floyd的评论中提到了一个类:我使用了一种需要WeakReference的特殊方式,但您可以轻松地将其更改为任何对象。
希望这能有助于某个人的某一天 :)
import java.lang.ref.WeakReference;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Queue;
public class Array2DWeakRefsBuffered<T>
{
private final WeakReference<T>[][] _array;
private final Queue<T> _buffer;
private final int _width;
private final int _height;
private final int _bufferSize;
@SuppressWarnings( "unchecked" )
public Array2DWeakRefsBuffered( int w , int h , int bufferSize )
{
_width = w;
_height = h;
_bufferSize = bufferSize;
_array = new WeakReference[_width][_height];
_buffer = new LinkedList<T>();
}
public boolean exists( int x , int y ) throws IndexOutOfBoundsException
{
if( x >= _width || x < 0 )
{
throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ x = " + x + "]" );
}
if( y >= _height || y < 0 )
{
throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ y = " + y + "]" );
}
if( _array[x][y] != null )
{
T elem = _array[x][y].get();
if( elem != null )
{
return true;
}
}
return false;
}
public T get( int x , int y ) throws IndexOutOfBoundsException , NoSuchElementException
{
T retour = null;
if( x >= _width || x < 0 )
{
throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ x = " + x + "]" );
}
if( y >= _height || y < 0 )
{
throw new IndexOutOfBoundsException( "Index out of bounds (get) : [ y = " + y + "]" );
}
if( _array[x][y] != null )
{
retour = _array[x][y].get();
if( retour == null )
{
throw new NoSuchElementException( "Dereferenced WeakReference element at [ " + x + " ; " + y + "]" );
}
}
else
{
throw new NoSuchElementException( "No WeakReference element at [ " + x + " ; " + y + "]" );
}
return retour;
}
public void set( T o , int x , int y ) throws IndexOutOfBoundsException
{
if( x >= _width || x < 0 )
{
throw new IndexOutOfBoundsException( "Index out of bounds (set) : [ x = " + x + "]" );
}
if( y >= _height || y < 0 )
{
throw new IndexOutOfBoundsException( "Index out of bounds (set) : [ y = " + y + "]" );
}
_array[x][y] = new WeakReference<T>( o );
_buffer.add( o );
if(_buffer.size() > _bufferSize)
{
_buffer.poll();
}
}
}
使用示例:
// a 5x5 array, with at most 10 elements "bufferized" -> the last 10 elements will not be taken by GC process
Array2DWeakRefsBuffered<Image> myArray = new Array2DWeakRefsBuffered<Image>(5,5,10);
Image img = myArray.set(anImage,0,0);
if(myArray.exists(3,3))
{
System.out.println("Image at 3,3 is still in memory");
}