শন প্যাট্রিক ফ্লয়েডের সাথে আমরা যে মন্তব্য করেছি তাতে আমি ক্লাসটি উল্লেখ করেছি: আমি এটি একটি অদ্ভুত ব্যবহার দিয়ে করেছি যা WeakReferences প্রয়োজন, তবে আপনি যে কোনও বস্তু দ্বারা এটি সহজেই পরিবর্তন করতে পারেন।
এটি আশা করা যে কোনও দিন কাউকে সহায়তা করতে পারে :)
import java.lang.ref.WeakReference;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.Queue;
/**
*
* @author leBenj
*/
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>();
}
/**
* Tests the existence of the encapsulated object
* /!\ This DOES NOT ensure that the object will be available on next call !
* @param x
* @param y
* @return
* @throws IndexOutOfBoundsException
*/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;
}
/**
* Gets the encapsulated object
* @param x
* @param y
* @return
* @throws IndexOutOfBoundsException
* @throws NoSuchElementException
*/
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;
}
/**
* Add/replace an object
* @param o
* @param x
* @param y
* @throws IndexOutOfBoundsException
*/
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 );
// store local "visible" references : avoids deletion, works in FIFO mode
_buffer.add( o );
if(_buffer.size() > _bufferSize)
{
_buffer.poll();
}
}
}
এটি কীভাবে ব্যবহার করবেন তার উদাহরণ:
// 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");
}