1/* 2 * Copyright (C) 2011 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.cache; 18 19import static com.google.common.base.Preconditions.checkNotNull; 20 21import com.google.common.annotations.Beta; 22import com.google.common.base.Objects; 23 24import java.util.Map.Entry; 25 26import javax.annotation.Nullable; 27 28/** 29 * A notification of the removal of a single entry. The key and/or value may be null if they were 30 * already garbage collected. 31 * 32 * <p>Like other {@code Map.Entry} instances associated with {@code CacheBuilder}, this class holds 33 * strong references to the key and value, regardless of the type of references the cache may be 34 * using. 35 * 36 * @author Charles Fry 37 * @since 10.0 38 */ 39@Beta 40public final class RemovalNotification<K, V> implements Entry<K, V> { 41 @Nullable private final K key; 42 @Nullable private final V value; 43 private final RemovalCause cause; 44 45 RemovalNotification(@Nullable K key, @Nullable V value, RemovalCause cause) { 46 this.key = key; 47 this.value = value; 48 this.cause = checkNotNull(cause); 49 } 50 51 /** 52 * Returns the cause for which the entry was removed. 53 */ 54 public RemovalCause getCause() { 55 return cause; 56 } 57 58 /** 59 * Returns {@code true} if there was an automatic removal due to eviction (the cause is neither 60 * {@link RemovalCause#EXPLICIT} nor {@link RemovalCause#REPLACED}). 61 */ 62 public boolean wasEvicted() { 63 return cause.wasEvicted(); 64 } 65 66 @Nullable @Override public K getKey() { 67 return key; 68 } 69 70 @Nullable @Override public V getValue() { 71 return value; 72 } 73 74 @Override public final V setValue(V value){ 75 throw new UnsupportedOperationException(); 76 } 77 78 @Override public boolean equals(@Nullable Object object) { 79 if (object instanceof Entry) { 80 Entry<?, ?> that = (Entry<?, ?>) object; 81 return Objects.equal(this.getKey(), that.getKey()) 82 && Objects.equal(this.getValue(), that.getValue()); 83 } 84 return false; 85 } 86 87 @Override public int hashCode() { 88 K k = getKey(); 89 V v = getValue(); 90 return ((k == null) ? 0 : k.hashCode()) ^ ((v == null) ? 0 : v.hashCode()); 91 } 92 93 /** 94 * Returns a string representation of the form <code>{key}={value}</code>. 95 */ 96 @Override public String toString() { 97 return getKey() + "=" + getValue(); 98 } 99 private static final long serialVersionUID = 0; 100} 101