src/com/google/common/base/FinalizableWeakReference.java

/*
 * Copyright (C) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.base;

import java.lang.ref.WeakReference;

/**
 * Weak reference with a {@code finalizeReferent()} method which a background
 * thread invokes after the garbage collector reclaims the referent. This is a
 * simpler alternative to using a {@link java.lang.ref.ReferenceQueue}.
 *
 * @author Bob Lee
 */
public abstract class FinalizableWeakReference<T> extends WeakReference<T>
    implements FinalizableReference {

  /**
   * Constructs a new finalizable weak reference.
   *
   * @param referent to weakly reference
   * @param queue that should finalize the referent
   */
  protected FinalizableWeakReference(T referent,
      FinalizableReferenceQueue queue) {
    super(referent, queue.queue);
    queue.cleanUp();
  }
}