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