1 /* 2 * Copyright (C) 2007 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 5 * in compliance with the License. You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software distributed under the License 10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 11 * or implied. See the License for the specific language governing permissions and limitations under 12 * the License. 13 */ 14 15 package com.google.common.collect; 16 17 import static com.google.common.base.Preconditions.checkArgument; 18 19 import com.google.common.annotations.GwtCompatible; 20 import com.google.common.annotations.GwtIncompatible; 21 22 import java.io.IOException; 23 import java.io.ObjectInputStream; 24 import java.io.ObjectOutputStream; 25 import java.util.EnumMap; 26 import java.util.Iterator; 27 28 /** 29 * Multiset implementation backed by an {@link EnumMap}. 30 * 31 * @author Jared Levy 32 * @since 2.0 (imported from Google Collections Library) 33 */ 34 @GwtCompatible(emulated = true) 35 public final class EnumMultiset<E extends Enum<E>> extends AbstractMapBasedMultiset<E> { 36 /** Creates an empty {@code EnumMultiset}. */ 37 public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) { 38 return new EnumMultiset<E>(type); 39 } 40 41 /** 42 * Creates a new {@code EnumMultiset} containing the specified elements. 43 * 44 * <p>This implementation is highly efficient when {@code elements} is itself a {@link 45 * Multiset}. 46 * 47 * @param elements the elements that the multiset should contain 48 * @throws IllegalArgumentException if {@code elements} is empty 49 */ 50 public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) { 51 Iterator<E> iterator = elements.iterator(); 52 checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable"); 53 EnumMultiset<E> multiset = new EnumMultiset<E>(iterator.next().getDeclaringClass()); 54 Iterables.addAll(multiset, elements); 55 return multiset; 56 } 57 58 private transient Class<E> type; 59 60 /** Creates an empty {@code EnumMultiset}. */ 61 private EnumMultiset(Class<E> type) { 62 super(WellBehavedMap.wrap(new EnumMap<E, Count>(type))); 63 this.type = type; 64 } 65 66 @GwtIncompatible("java.io.ObjectOutputStream") 67 private void writeObject(ObjectOutputStream stream) throws IOException { 68 stream.defaultWriteObject(); 69 stream.writeObject(type); 70 Serialization.writeMultiset(this, stream); 71 } 72 73 /** 74 * @serialData the {@code Class<E>} for the enum type, the number of distinct 75 * elements, the first element, its count, the second element, its 76 * count, and so on 77 */ 78 @GwtIncompatible("java.io.ObjectInputStream") 79 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { 80 stream.defaultReadObject(); 81 @SuppressWarnings("unchecked") // reading data stored by writeObject 82 Class<E> localType = (Class<E>) stream.readObject(); 83 type = localType; 84 setBackingMap(WellBehavedMap.wrap(new EnumMap<E, Count>(type))); 85 Serialization.populateMultiset(this, stream); 86 } 87 88 @GwtIncompatible("Not needed in emulated source") 89 private static final long serialVersionUID = 0; 90 } 91
