001/* 002 * Copyright (C) 2007 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package com.google.common.collect; 018 019import static com.google.common.base.Preconditions.checkArgument; 020import static com.google.common.base.Preconditions.checkNotNull; 021 022import com.google.common.annotations.GwtCompatible; 023import com.google.common.annotations.GwtIncompatible; 024import java.io.IOException; 025import java.io.ObjectInputStream; 026import java.io.ObjectOutputStream; 027import java.util.EnumMap; 028import java.util.Map; 029 030/** 031 * A {@code BiMap} backed by two {@code EnumMap} instances. Null keys and values are not permitted. 032 * An {@code EnumBiMap} and its inverse are both serializable. 033 * 034 * <p>See the Guava User Guide article on <a href= 035 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>. 036 * 037 * @author Mike Bostock 038 * @since 2.0 039 */ 040@GwtCompatible(emulated = true) 041@ElementTypesAreNonnullByDefault 042public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>> extends AbstractBiMap<K, V> { 043 private transient Class<K> keyType; 044 private transient Class<V> valueType; 045 046 /** 047 * Returns a new, empty {@code EnumBiMap} using the specified key and value types. 048 * 049 * @param keyType the key type 050 * @param valueType the value type 051 */ 052 public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V> create( 053 Class<K> keyType, Class<V> valueType) { 054 return new EnumBiMap<>(keyType, valueType); 055 } 056 057 /** 058 * Returns a new bimap with the same mappings as the specified map. If the specified map is an 059 * {@code EnumBiMap}, the new bimap has the same types as the provided map. Otherwise, the 060 * specified map must contain at least one mapping, in order to determine the key and value types. 061 * 062 * @param map the map whose mappings are to be placed in this map 063 * @throws IllegalArgumentException if map is not an {@code EnumBiMap} instance and contains no 064 * mappings 065 */ 066 public static <K extends Enum<K>, V extends Enum<V>> EnumBiMap<K, V> create(Map<K, V> map) { 067 EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map)); 068 bimap.putAll(map); 069 return bimap; 070 } 071 072 private EnumBiMap(Class<K> keyType, Class<V> valueType) { 073 super(new EnumMap<K, V>(keyType), new EnumMap<V, K>(valueType)); 074 this.keyType = keyType; 075 this.valueType = valueType; 076 } 077 078 static <K extends Enum<K>> Class<K> inferKeyType(Map<K, ?> map) { 079 if (map instanceof EnumBiMap) { 080 return ((EnumBiMap<K, ?>) map).keyType(); 081 } 082 if (map instanceof EnumHashBiMap) { 083 return ((EnumHashBiMap<K, ?>) map).keyType(); 084 } 085 checkArgument(!map.isEmpty()); 086 return map.keySet().iterator().next().getDeclaringClass(); 087 } 088 089 private static <V extends Enum<V>> Class<V> inferValueType(Map<?, V> map) { 090 if (map instanceof EnumBiMap) { 091 return ((EnumBiMap<?, V>) map).valueType; 092 } 093 checkArgument(!map.isEmpty()); 094 return map.values().iterator().next().getDeclaringClass(); 095 } 096 097 /** Returns the associated key type. */ 098 public Class<K> keyType() { 099 return keyType; 100 } 101 102 /** Returns the associated value type. */ 103 public Class<V> valueType() { 104 return valueType; 105 } 106 107 @Override 108 K checkKey(K key) { 109 return checkNotNull(key); 110 } 111 112 @Override 113 V checkValue(V value) { 114 return checkNotNull(value); 115 } 116 117 /** 118 * @serialData the key class, value class, number of entries, first key, first value, second key, 119 * second value, and so on. 120 */ 121 @GwtIncompatible // java.io.ObjectOutputStream 122 private void writeObject(ObjectOutputStream stream) throws IOException { 123 stream.defaultWriteObject(); 124 stream.writeObject(keyType); 125 stream.writeObject(valueType); 126 Serialization.writeMap(this, stream); 127 } 128 129 @SuppressWarnings("unchecked") // reading fields populated by writeObject 130 @GwtIncompatible // java.io.ObjectInputStream 131 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { 132 stream.defaultReadObject(); 133 keyType = (Class<K>) stream.readObject(); 134 valueType = (Class<V>) stream.readObject(); 135 setDelegates(new EnumMap<K, V>(keyType), new EnumMap<V, K>(valueType)); 136 Serialization.populateMap(this, stream); 137 } 138 139 @GwtIncompatible // not needed in emulated source. 140 private static final long serialVersionUID = 0; 141}