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Commons Collections example source code file (TransformedList.java)

This example Commons Collections source code file (TransformedList.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

abstractlistiteratordecorator, collection, list, list, listiterator, object, object, transformedcollection, transformedlist, transformedlist, transformedlistiterator, transformedlistiterator, transformer, util

The Commons Collections TransformedList.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.list;

import java.util.Collection;
import java.util.List;
import java.util.ListIterator;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.collection.TransformedCollection;
import org.apache.commons.collections.iterators.AbstractListIteratorDecorator;

/**
 * Decorates another <code>List to transform objects that are added.
 * <p>
 * The add and set methods are affected by this class.
 * Thus objects must be removed or searched for using their transformed form.
 * For example, if the transformation converts Strings to Integers, you must
 * use the Integer form to remove objects.
 * <p>
 * This class is Serializable from Commons Collections 3.1.
 *
 * @since Commons Collections 3.0
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
 * 
 * @author Stephen Colebourne
 */
public class TransformedList extends TransformedCollection implements List {

    /** Serialization version */
    private static final long serialVersionUID = 1077193035000013141L;

    /**
     * Factory method to create a transforming list.
     * <p>
     * If there are any elements already in the list being decorated, they
     * are NOT transformed.
     * 
     * @param list  the list to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @throws IllegalArgumentException if list or transformer is null
     */
    public static List decorate(List list, Transformer transformer) {
        return new TransformedList(list, transformer);
    }
    
    //-----------------------------------------------------------------------
    /**
     * Constructor that wraps (not copies).
     * <p>
     * If there are any elements already in the list being decorated, they
     * are NOT transformed.
     * 
     * @param list  the list to decorate, must not be null
     * @param transformer  the transformer to use for conversion, must not be null
     * @throws IllegalArgumentException if list or transformer is null
     */
    protected TransformedList(List list, Transformer transformer) {
        super(list, transformer);
    }

    /**
     * Gets the decorated list.
     * 
     * @return the decorated list
     */
    protected List getList() {
        return (List) collection;
    }

    //-----------------------------------------------------------------------
    public Object get(int index) {
        return getList().get(index);
    }

    public int indexOf(Object object) {
        return getList().indexOf(object);
    }

    public int lastIndexOf(Object object) {
        return getList().lastIndexOf(object);
    }

    public Object remove(int index) {
        return getList().remove(index);
    }

    //-----------------------------------------------------------------------
    public void add(int index, Object object) {
        object = transform(object);
        getList().add(index, object);
    }

    public boolean addAll(int index, Collection coll) {
        coll = transform(coll);
        return getList().addAll(index, coll);
    }

    public ListIterator listIterator() {
        return listIterator(0);
    }

    public ListIterator listIterator(int i) {
        return new TransformedListIterator(getList().listIterator(i));
    }

    public Object set(int index, Object object) {
        object = transform(object);
        return getList().set(index, object);
    }

    public List subList(int fromIndex, int toIndex) {
        List sub = getList().subList(fromIndex, toIndex);
        return new TransformedList(sub, transformer);
    }

    /**
     * Inner class Iterator for the TransformedList
     */
    protected class TransformedListIterator extends AbstractListIteratorDecorator {
        
        protected TransformedListIterator(ListIterator iterator) {
            super(iterator);
        }
        
        public void add(Object object) {
            object = transform(object);
            iterator.add(object);
        }
        
        public void set(Object object) {
            object = transform(object);
            iterator.set(object);
        }
    }

}

Other Commons Collections examples (source code examples)

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