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/*
* Copyright (C) 2007 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.collect;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.Nullable;
/**
* A {@code BiMap} backed by an {@code EnumMap} instance for keys-to-values, and
* a {@code HashMap} instance for values-to-keys. Null keys are not permitted,
* but null values are. An {@code EnumHashBiMap} and its inverse are both
* serializable.
*
* <p>See the Guava User Guide article on <a href=
* "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#BiMap">
* {@code BiMap}</a>.
*
* @author Mike Bostock
* @since 2.0 (imported from Google Collections Library)
*/
@GwtCompatible(emulated = true)
public final class EnumHashBiMap<K extends Enum<K>, V>
extends AbstractBiMap<K, V> {
private transient Class<K> keyType;
/**
* Returns a new, empty {@code EnumHashBiMap} using the specified key type.
*
* @param keyType the key type
*/
public static <K extends Enum<K>, V> EnumHashBiMap<K, V>
create(Class<K> keyType) {
return new EnumHashBiMap<K, V>(keyType);
}
/**
* Constructs a new bimap with the same mappings as the specified map. If the
* specified map is an {@code EnumHashBiMap} or an {@link EnumBiMap}, the new
* bimap has the same key type as the input bimap. Otherwise, the specified
* map must contain at least one mapping, in order to determine the key type.
*
* @param map the map whose mappings are to be placed in this map
* @throws IllegalArgumentException if map is not an {@code EnumBiMap} or an
* {@code EnumHashBiMap} instance and contains no mappings
*/
public static <K extends Enum<K>, V> EnumHashBiMap<K, V>
create(Map<K, ? extends V> map) {
EnumHashBiMap<K, V> bimap = create(EnumBiMap.inferKeyType(map));
bimap.putAll(map);
return bimap;
}
private EnumHashBiMap(Class<K> keyType) {
super(WellBehavedMap.wrap(
new EnumMap<K, V>(keyType)),
Maps.<V, K>newHashMapWithExpectedSize(
keyType.getEnumConstants().length));
this.keyType = keyType;
}
// Overriding these 3 methods to show that values may be null (but not keys)
@Override
K checkKey(K key) {
return checkNotNull(key);
}
@Override public V put(K key, @Nullable V value) {
return super.put(key, value);
}
@Override public V forcePut(K key, @Nullable V value) {
return super.forcePut(key, value);
}
/** Returns the associated key type. */
public Class<K> keyType() {
return keyType;
}
/**
* @serialData the key class, number of entries, first key, first value,
* second key, second value, and so on.
*/
@GwtIncompatible("java.io.ObjectOutputStream")
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(keyType);
Serialization.writeMap(this, stream);
}
@SuppressWarnings("unchecked") // reading field populated by writeObject
@GwtIncompatible("java.io.ObjectInputStream")
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
keyType = (Class<K>) stream.readObject();
setDelegates(WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
new HashMap<V, K>(keyType.getEnumConstants().length * 3 / 2));
Serialization.populateMap(this, stream);
}
@GwtIncompatible("only needed in emulated source.")
private static final long serialVersionUID = 0;
}
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