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Commons Collections example source code file (TreeBag.java)

This example Commons Collections source code file (TreeBag.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Collections tags/keywords

abstractmapbag, classnotfoundexception, comparator, comparator, io, ioexception, object, serializable, sortedbag, sortedmap, sortedmap, treebag, treebag, treemap, treemap, util

The Commons Collections TreeBag.java source code

/*
 *  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 <code>SortedBag, using a TreeMap to provide
 * the data storage. This is the standard implementation of a sorted bag.
 * <p>
 * Order will be maintained among the bag members and can be viewed through the
 * iterator.
 * <p>
 * A <code>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
 * <code>Collection interface specification.
 *
 * @since Commons Collections 3.0 (previously in main package v2.0)
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (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 <code>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 <code>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);
    }
    
}

Other Commons Collections examples (source code examples)

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