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Java example source code file (EnumBiMap.java)

This example Java source code file (EnumBiMap.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractbimap, class, classnotfoundexception, enum, enumbimap, enumhashbimap, enummap, gwtincompatible, ioexception, override, suppresswarnings, util

The EnumBiMap.java Java example source code

/*
 * 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.
 *
 * <p>See the Guava User Guide article on > extends AbstractBiMap {
  private transient Class<K> keyType;
  private transient Class<V> 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 <K extends Enum> EnumBiMap create(
      Class<K> keyType, Class valueType) {
    return new EnumBiMap<K, V>(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 <K extends Enum> EnumBiMap create(Map map) {
    EnumBiMap<K, V> bimap = create(inferKeyType(map), inferValueType(map));
    bimap.putAll(map);
    return bimap;
  }

  private EnumBiMap(Class<K> keyType, Class valueType) {
    super(
        WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
        WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
    this.keyType = keyType;
    this.valueType = valueType;
  }

  static <K extends Enum Class inferKeyType(Map map) {
    if (map instanceof EnumBiMap) {
      return ((EnumBiMap<K, ?>) map).keyType();
    }
    if (map instanceof EnumHashBiMap) {
      return ((EnumHashBiMap<K, ?>) map).keyType();
    }
    checkArgument(!map.isEmpty());
    return map.keySet().iterator().next().getDeclaringClass();
  }

  private static <V extends Enum Class inferValueType(Map map) {
    if (map instanceof EnumBiMap) {
      return ((EnumBiMap<?, V>) map).valueType;
    }
    checkArgument(!map.isEmpty());
    return map.values().iterator().next().getDeclaringClass();
  }

  /** Returns the associated key type. */
  public Class<K> keyType() {
    return keyType;
  }

  /** Returns the associated value type. */
  public Class<V> 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<K>) stream.readObject();
    valueType = (Class<V>) stream.readObject();
    setDelegates(
        WellBehavedMap.wrap(new EnumMap<K, V>(keyType)),
        WellBehavedMap.wrap(new EnumMap<V, K>(valueType)));
    Serialization.populateMap(this, stream);
  }

  @GwtIncompatible // not needed in emulated source.
  private static final long serialVersionUID = 0;
}
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