com.google.common.collect.EnumHashBiMap Maven / Gradle / Ivy
/*
* 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 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.
*
* @author Mike Bostock
* @since 2 (imported from Google Collections Library)
*/
public final class EnumHashBiMap, V>
extends AbstractBiMap {
private transient Class keyType;
/**
* Returns a new, empty {@code EnumHashBiMap} using the specified key type.
*
* @param keyType the key type
*/
public static , V> EnumHashBiMap
create(Class keyType) {
return new EnumHashBiMap(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 , V> EnumHashBiMap
create(Map map) {
EnumHashBiMap bimap = create(EnumBiMap.inferKeyType(map));
bimap.putAll(map);
return bimap;
}
private EnumHashBiMap(Class keyType) {
super(new EnumMap(keyType), Maps.newHashMapWithExpectedSize(
keyType.getEnumConstants().length));
this.keyType = keyType;
}
// Overriding these two methods to show that values may be null (but not keys)
@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 keyType() {
return keyType;
}
/**
* @serialData the key class, number of entries, first key, first value,
* second key, second value, and so on.
*/
private void writeObject(ObjectOutputStream stream) throws IOException {
stream.defaultWriteObject();
stream.writeObject(keyType);
Serialization.writeMap(this, stream);
}
@SuppressWarnings("unchecked") // reading field populated by writeObject
private void readObject(ObjectInputStream stream)
throws IOException, ClassNotFoundException {
stream.defaultReadObject();
keyType = (Class) stream.readObject();
setDelegates(new EnumMap(keyType),
new HashMap(keyType.getEnumConstants().length * 3 / 2));
Serialization.populateMap(this, stream);
}
private static final long serialVersionUID = 0;
}