1/*
2 * Copyright (C) 2007 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.base;
18
19import java.lang.ref.PhantomReference;
20import java.lang.ref.ReferenceQueue;
21
22/**
23 * Phantom reference with a {@code finalizeReferent()} method which a background thread invokes
24 * after the garbage collector reclaims the referent. This is a simpler alternative to using a
25 * {@link ReferenceQueue}.
26 *
27 * <p>Unlike a normal phantom reference, this reference will be cleared automatically.
28 *
29 * @author Bob Lee
30 * @since 2.0 (imported from Google Collections Library)
31 */
32public abstract class FinalizablePhantomReference<T> extends PhantomReference<T>
33    implements FinalizableReference {
34  /**
35   * Constructs a new finalizable phantom reference.
36   *
37   * @param referent to phantom reference
38   * @param queue that should finalize the referent
39   */
40  protected FinalizablePhantomReference(T referent, FinalizableReferenceQueue queue) {
41    super(referent, queue.queue);
42    queue.cleanUp();
43  }
44}
45