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/*
* Copyright (C) 2011 The Guava Authors
*
* 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.cache;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.base.Objects;
import java.util.Map.Entry;
import javax.annotation.Nullable;
/**
* A notification of the removal of a single entry. The key and/or value may be null if they were
* already garbage collected.
*
* <p>Like other {@code Map.Entry} instances associated with {@code CacheBuilder}, this class holds
* strong references to the key and value, regardless of the type of references the cache may be
* using.
*
* @author Charles Fry
* @since 10.0
*/
@Beta
public final class RemovalNotification<K, V> implements Entry<K, V> {
@Nullable private final K key;
@Nullable private final V value;
private final RemovalCause cause;
RemovalNotification(@Nullable K key, @Nullable V value, RemovalCause cause) {
this.key = key;
this.value = value;
this.cause = checkNotNull(cause);
}
/**
* Returns the cause for which the entry was removed.
*/
public RemovalCause getCause() {
return cause;
}
/**
* Returns {@code true} if there was an automatic removal due to eviction (the cause is neither
* {@link RemovalCause#EXPLICIT} nor {@link RemovalCause#REPLACED}).
*/
public boolean wasEvicted() {
return cause.wasEvicted();
}
@Nullable @Override public K getKey() {
return key;
}
@Nullable @Override public V getValue() {
return value;
}
@Override public final V setValue(V value){
throw new UnsupportedOperationException();
}
@Override public boolean equals(@Nullable Object object) {
if (object instanceof Entry) {
Entry<?, ?> that = (Entry<?, ?>) object;
return Objects.equal(this.getKey(), that.getKey())
&& Objects.equal(this.getValue(), that.getValue());
}
return false;
}
@Override public int hashCode() {
K k = getKey();
V v = getValue();
return ((k == null) ? 0 : k.hashCode()) ^ ((v == null) ? 0 : v.hashCode());
}
/**
* Returns a string representation of the form <code>{key}={value}</code>.
*/
@Override public String toString() {
return getKey() + "=" + getValue();
}
private static final long serialVersionUID = 0;
}
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