54 lines
1.2 KiB
Java
54 lines
1.2 KiB
Java
/*
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* Copyright (c) 2015-present, Parse, LLC.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*/
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package com.parse;
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import java.lang.ref.WeakReference;
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import java.util.HashMap;
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/**
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* A HashMap where all the values are weak.
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*/
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/** package */ class WeakValueHashMap<K, V> {
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private HashMap<K, WeakReference<V>> map;
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public WeakValueHashMap() {
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map = new HashMap<>();
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}
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public void put(K key, V value) {
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map.put(key, new WeakReference<>(value));
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}
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/**
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* Returns null if the key isn't in the map, or if it is an expired reference. If it is, then the
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* reference is removed from the map.
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*/
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public V get(K key) {
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WeakReference<V> reference = map.get(key);
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if (reference == null) {
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return null;
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}
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V value = reference.get();
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if (value == null) {
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map.remove(key);
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}
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return value;
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}
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public void remove(K key) {
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map.remove(key);
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}
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public void clear() {
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map.clear();
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}
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}
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