org.apache.commons.collections.bag.TreeBag 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.collections.bag;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Collection;
import java.util.Comparator;
import java.util.SortedMap;
import java.util.TreeMap;
import org.apache.commons.collections.SortedBag;
/**
* Implements SortedBag, using a TreeMap to provide
* the data storage. This is the standard implementation of a sorted bag.
*
* Order will be maintained among the bag members and can be viewed through the
* iterator.
*
* A Bag 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. It is important to read the
* interface javadoc carefully as several methods violate the
* Collection interface specification.
*
* @since Commons Collections 3.0 (previously in main package v2.0)
* @version $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
*
* @author Chuck Burdick
* @author Stephen Colebourne
*/
public class TreeBag
extends AbstractMapBag implements SortedBag, Serializable {
/** Serial version lock */
private static final long serialVersionUID = -7740146511091606676L;
/**
* Constructs an empty TreeBag.
*/
public TreeBag() {
super(new TreeMap());
}
/**
* Constructs an empty bag that maintains order on its unique
* representative members according to the given {@link Comparator}.
*
* @param comparator the comparator to use
*/
public TreeBag(Comparator comparator) {
super(new TreeMap(comparator));
}
/**
* Constructs a TreeBag containing all the members of the
* specified collection.
*
* @param coll the collection to copy into the bag
*/
public TreeBag(Collection coll) {
this();
addAll(coll);
}
//-----------------------------------------------------------------------
public Object first() {
return ((SortedMap) getMap()).firstKey();
}
public Object last() {
return ((SortedMap) getMap()).lastKey();
}
public Comparator comparator() {
return ((SortedMap) getMap()).comparator();
}
//-----------------------------------------------------------------------
/**
* Write the bag out using a custom routine.
*/
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeObject(comparator());
super.doWriteObject(out);
}
/**
* Read the bag in using a custom routine.
*/
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
Comparator comp = (Comparator) in.readObject();
super.doReadObject(new TreeMap(comp), in);
}
}