org.apache.commons.collections4.multiset.HashMultiSet Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.collections4.multiset;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Collection;
import java.util.HashMap;
/**
* Implements {@code MultiSet}, using a {@link HashMap} to provide the
* data storage. This is the standard implementation of a multiset.
*
* A {@code MultiSet} stores each object in the collection together with a
* count of occurrences. Extra methods on the interface allow multiple copies
* of an object to be added or removed at once.
*
* @param the type held in the multiset
* @since 4.1
*/
public class HashMultiSet extends AbstractMapMultiSet implements Serializable {
/** Serial version lock */
private static final long serialVersionUID = 20150610L;
/**
* Constructs an empty {@link HashMultiSet}.
*/
public HashMultiSet() {
super(new HashMap());
}
/**
* Constructs a multiset containing all the members of the given collection.
*
* @param coll a collection to copy into this multiset
*/
public HashMultiSet(final Collection coll) {
this();
addAll(coll);
}
//-----------------------------------------------------------------------
/**
* Write the multiset out using a custom routine.
*
* @param out the output stream
* @throws IOException if an error occurs while writing to the stream
*/
private void writeObject(final ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
super.doWriteObject(out);
}
/**
* Read the multiset in using a custom routine.
*
* @param in the input stream
* @throws IOException if an error occurs while reading from the stream
* @throws ClassNotFoundException if an object read from the stream can not be loaded
*/
private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
setMap(new HashMap());
super.doReadObject(in);
}
}