DMDirc-Util/src/com/dmdirc/util/collections/EquatableWeakReference.java

/*
 * Copyright (c) 2006-2015 DMDirc Developers
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.dmdirc.util.collections;

import java.lang.ref.Reference;
import java.lang.ref.WeakReference;

/**
 * An extension of WeakReference that implements a sane equals and hashcode
 * method.
 *
 * @param <T> The type of object that this reference contains
 */
public class EquatableWeakReference<T> extends WeakReference<T> {

    /**
     * Creates a new instance of EquatableWeakReference.
     *
     * @param referent The object that this weak reference should reference.
     */
    public EquatableWeakReference(final T referent) {
        super(referent);
    }

    @Override
    public boolean equals(final Object obj) {
        if (get() == null) {
            return obj == null;
        }
        if (obj instanceof Reference<?>) {
            return get().equals(((Reference<?>) obj).get());
        } else {
            return get().equals(obj);
        }
    }

    @Override
    public int hashCode() {
        if (get() == null) {
            return 0;
        }
        return get().hashCode();
    }

}