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68
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     1 /*
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     2 Copyright (c) 2008  Franklin Schmidt <fschmidt@gmail.com>
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     3 
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     4 Permission is hereby granted, free of charge, to any person obtaining a copy
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     5 of this software and associated documentation files (the "Software"), to deal
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     6 in the Software without restriction, including without limitation the rights
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     7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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     8 copies of the Software, and to permit persons to whom the Software is
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     9 furnished to do so, subject to the following conditions:
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    10 
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    11 The above copyright notice and this permission notice shall be included in
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    12 all copies or substantial portions of the Software.
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    13 
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    14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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    15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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    16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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    17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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    18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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    19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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    20 THE SOFTWARE.
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    21 */
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    22 
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    23 package fschmidt.util.java;
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    24 
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    25 import java.util.List;
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    26 import java.util.AbstractList;
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    27 import java.util.ArrayList;
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    28 import java.lang.ref.WeakReference;
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    29 
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    30 
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    31 public final class WeakList<E> extends AbstractList<E> {
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    32 	private List<WeakReference<E>> list = new ArrayList<WeakReference<E>>();
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    33 
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    34 	public void removeNulls() {
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    35 		while( remove(null) );
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    36 	}
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    37 
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    38 	public int size() {
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    39 		return list.size();
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    40 	}
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    41 
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    42 	public E get(int index) {
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    43 		WeakReference<E> ref = list.get(index);
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    44 		return ref==null ? null : ref.get();
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    45 	}
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    46 
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    47 	public E set(int index,E element) {
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    48 		WeakReference<E> ref = list.set(index,new WeakReference<E>(element));
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    49 		return ref==null ? null : ref.get();
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    50 	}
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    51 
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    52 	public boolean add(E element) {
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    53 		return list.add(new WeakReference<E>(element));
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    54 	}
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    55 
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    56 	public void add(int index,E element) {
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    57 		list.add(index,new WeakReference<E>(element));
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    58 	}
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    59 
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    60 	public E remove(int index) {
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    61 		WeakReference<E> ref = list.remove(index);
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    62 		return ref==null ? null : ref.get();
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    63 	}
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    64 
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    65 	public <T> T[] toArray(T[] a) {
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    66 		removeNulls();
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    67 		return super.toArray(a);
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    68 	}
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    69 }
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