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/*
* 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.collect;
import com.google.common.base.Nullable;
import com.google.common.base.Objects;
import java.util.Map.Entry;
/**
* Implementation of the {@code equals}, {@code hashCode}, and {@code toString}
* methods of {@code Entry}.
*
* @author Jared Levy
*/
public abstract class AbstractMapEntry implements Entry {
public abstract K getKey();
public abstract V getValue();
/**
* {@inheritDoc}
*
* This implementation throws an {@link UnsupportedOperationException}.
* Override this method to support mutable map entries.
*/
public V setValue(V value) {
throw new UnsupportedOperationException();
}
/**
* Indicates whether an object equals this entry, following the behavior
* specified in {@link Entry#equals}.
*/
@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;
}
/**
* Return this entry's hash code, following the behavior specified in
* {@link Entry#hashCode}.
*/
@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 {key}={value}.
*/
@Override public String toString() {
return getKey() + "=" + getValue();
}
}