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 * <p>See the Guava User Guide article on <a href= 32 * "http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained#Multiset"> 33 * {@code Multiset}</a>. 34 * 35 * @author Jared Levy 36 * @since 2.0 (imported from Google Collections Library) 37 */ 38 @GwtCompatible(emulated = true) 39 public final class EnumMultiset<E extends Enum<E>> extends AbstractMapBasedMultiset<E> { 40 /** Creates an empty {@code EnumMultiset}. */ 41 public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) { 42 return new EnumMultiset<E>(type); 43 } 44 45 /** 46 * Creates a new {@code EnumMultiset} containing the specified elements. 47 * 48 * <p>This implementation is highly efficient when {@code elements} is itself a {@link 49 * Multiset}. 50 * 51 * @param elements the elements that the multiset should contain 52 * @throws IllegalArgumentException if {@code elements} is empty 53 */ 54 public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) { 55 Iterator<E> iterator = elements.iterator(); 56 checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable"); 57 EnumMultiset<E> multiset = new EnumMultiset<E>(iterator.next().getDeclaringClass()); 58 Iterables.addAll(multiset, elements); 59 return multiset; 60 } 61 62 /** 63 * Returns a new {@code EnumMultiset} instance containing the given elements. Unlike 64 * {@link EnumMultiset#create(Iterable)}, this method does not produce an exception on an empty 65 * iterable. 66 * 67 * @since 14.0 68 */ 69 public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements, Class<E> type) { 70 EnumMultiset<E> result = create(type); 71 Iterables.addAll(result, elements); 72 return result; 73 } 74 75 private transient Class<E> type; 76 77 /** Creates an empty {@code EnumMultiset}. */ 78 private EnumMultiset(Class<E> type) { 79 super(WellBehavedMap.wrap(new EnumMap<E, Count>(type))); 80 this.type = type; 81 } 82 83 @GwtIncompatible("java.io.ObjectOutputStream") 84 private void writeObject(ObjectOutputStream stream) throws IOException { 85 stream.defaultWriteObject(); 86 stream.writeObject(type); 87 Serialization.writeMultiset(this, stream); 88 } 89 90 /** 91 * @serialData the {@code Class<E>} for the enum type, the number of distinct 92 * elements, the first element, its count, the second element, its 93 * count, and so on 94 */ 95 @GwtIncompatible("java.io.ObjectInputStream") 96 private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException { 97 stream.defaultReadObject(); 98 @SuppressWarnings("unchecked") // reading data stored by writeObject 99 Class<E> localType = (Class<E>) stream.readObject(); 100 type = localType; 101 setBackingMap(WellBehavedMap.wrap(new EnumMap<E, Count>(type))); 102 Serialization.populateMultiset(this, stream); 103 } 104 105 @GwtIncompatible("Not needed in emulated source") 106 private static final long serialVersionUID = 0; 107 } 108
