com.google.common.collect.EnumBiMap Maven / Gradle / Ivy
/*
* 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.checkArgument;
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.Map;
/**
* A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values are not permitted.
* An {@code EnumBiMap} and its inverse are both serializable.
*
* See the Guava User Guide article on {@code BiMap}.
*
* @author Mike Bostock
* @since 2.0
*/
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public final class EnumBiMap, V extends Enum> extends AbstractBiMap {
private transient Class keyType;
private transient Class valueType;
/**
* Returns a new, empty {@code EnumBiMap} using the specified key and value types.
*
* @param keyType the key type
* @param valueType the value type
*/
public static , V extends Enum> EnumBiMap create(
Class keyType, Class valueType) {
return new EnumBiMap<>(keyType, valueType);
}
/**
* Returns a new bimap with the same mappings as the specified map. If the specified map is an
* {@code EnumBiMap}, the new bimap has the same types as the provided map. Otherwise, the
* specified map must contain at least one mapping, in order to determine the key and value types.
*
* @param map the map whose mappings are to be placed in this map
* @throws IllegalArgumentException if map is not an {@code EnumBiMap} instance and contains no
* mappings
*/
public static , V extends Enum> EnumBiMap create(Map map) {
EnumBiMap bimap = create(inferKeyType(map), inferValueType(map));
bimap.putAll(map);
return bimap;
}
private EnumBiMap(Class keyType, Class valueType) {
super(new EnumMap(keyType), new EnumMap(valueType));
this.keyType = keyType;
this.valueType = valueType;
}
static > Class inferKeyType(Map map) {
if (map instanceof EnumBiMap) {
return ((EnumBiMap) map).keyType();
}
if (map instanceof EnumHashBiMap) {
return ((EnumHashBiMap) map).keyType();
}
checkArgument(!map.isEmpty());
return map.keySet().iterator().next().getDeclaringClass();
}
private static > Class inferValueType(Map map) {
if (map instanceof EnumBiMap) {
return ((EnumBiMap) map).valueType;
}
checkArgument(!map.isEmpty());
return map.values().iterator().next().getDeclaringClass();
}
/** Returns the associated key type. */
public Class keyType() {
return keyType;
}
/** Returns the associated value type. */
public Class valueType() {
return valueType;
}
@Override
K checkKey(K key) {
return checkNotNull(key);
}
@Override
V checkValue(V value) {
return checkNotNull(value);
}
/**
* @serialData the key class, value 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);
stream.writeObject(valueType);
Serialization.writeMap(this, stream);
}
@SuppressWarnings("unchecked") // reading fields populated by writeObject
@GwtIncompatible // java.io.ObjectInputStream
private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
stream.defaultReadObject();
keyType = (Class) stream.readObject();
valueType = (Class) stream.readObject();
setDelegates(new EnumMap(keyType), new EnumMap(valueType));
Serialization.populateMap(this, stream);
}
@GwtIncompatible // not needed in emulated source.
private static final long serialVersionUID = 0;
}