Update #0 - First Release

sources/main/java/com/google/common/collect/HashMultiset.java

@@ -0,0 +1,98 @@
+/*
+ * 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 java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.util.HashMap;
+
+import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.GwtIncompatible;
+
+/**
+ * Multiset implementation backed by a {@link HashMap}.
+ *
+ * @author Kevin Bourrillion
+ * @author Jared Levy
+ * @since 2.0 (imported from Google Collections Library)
+ */
+@GwtCompatible(serializable = true, emulated = true)
+public final class HashMultiset<E> extends AbstractMapBasedMultiset<E> {
+
+	/**
+	 * Creates a new, empty {@code HashMultiset} using the default initial capacity.
+	 */
+	public static <E> HashMultiset<E> create() {
+		return new HashMultiset<E>();
+	}
+
+	/**
+	 * Creates a new, empty {@code HashMultiset} with the specified expected number
+	 * of distinct elements.
+	 *
+	 * @param distinctElements the expected number of distinct elements
+	 * @throws IllegalArgumentException if {@code distinctElements} is negative
+	 */
+	public static <E> HashMultiset<E> create(int distinctElements) {
+		return new HashMultiset<E>(distinctElements);
+	}
+
+	/**
+	 * Creates a new {@code HashMultiset} containing the specified elements.
+	 * 
+	 * <p>
+	 * This implementation is highly efficient when {@code elements} is itself a
+	 * {@link Multiset}.
+	 * 
+	 * @param elements the elements that the multiset should contain
+	 */
+	public static <E> HashMultiset<E> create(Iterable<? extends E> elements) {
+		HashMultiset<E> multiset = create(Multisets.inferDistinctElements(elements));
+		Iterables.addAll(multiset, elements);
+		return multiset;
+	}
+
+	private HashMultiset() {
+		super(new HashMap<E, Count>());
+	}
+
+	private HashMultiset(int distinctElements) {
+		super(Maps.<E, Count>newHashMapWithExpectedSize(distinctElements));
+	}
+
+	/**
+	 * @serialData the number of distinct elements, the first element, its count,
+	 *             the second element, its count, and so on
+	 */
+	@GwtIncompatible("java.io.ObjectOutputStream")
+	private void writeObject(ObjectOutputStream stream) throws IOException {
+		stream.defaultWriteObject();
+		Serialization.writeMultiset(this, stream);
+	}
+
+	@GwtIncompatible("java.io.ObjectInputStream")
+	private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
+		stream.defaultReadObject();
+		int distinctElements = Serialization.readCount(stream);
+		setBackingMap(Maps.<E, Count>newHashMapWithExpectedSize(distinctElements));
+		Serialization.populateMultiset(this, stream, distinctElements);
+	}
+
+	@GwtIncompatible("Not needed in emulated source.")
+	private static final long serialVersionUID = 0;
+}