org.apache.commons.collections15.list.TransformedList.java Source code

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Here is the source code for org.apache.commons.collections15.list.TransformedList.java

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// GenericsNote: Converted, but unfortunately very little type-safety could be achieved without breaking List and ListIterator interfaces.
/*
 *  Copyright 2003-2004 The Apache Software Foundation
 *
 *  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 org.apache.commons.collections15.list;

import org.apache.commons.collections15.Transformer;
import org.apache.commons.collections15.collection.TransformedCollection;
import org.apache.commons.collections15.iterators.AbstractListIteratorDecorator;

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

/**
 * Decorates another <code>List</code> 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.
 * <p>
 * Note: This class cannot support generics without breaking the Collection contract.
 *
 * @author Matt Hall, John Watkinson, Stephen Colebourne
 * @version $Revision: 1.1 $ $Date: 2005/10/11 17:05:32 $
 * @since Commons Collections 3.0
 */
public class TransformedList<I, O> extends TransformedCollection<I, O> 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 <I, O> List<O> decorate(List<I> list, Transformer<? super I, ? extends O> transformer) {
        return new TransformedList<I, O>(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<I> list, Transformer<? super I, ? extends O> transformer) {
        super(list, transformer);
    }

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

    //-----------------------------------------------------------------------
    public O 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) {
        O transformed = transform((I) object);
        getList().add(index, transformed);
    }

    /**
     * Type-safe version of {@link #add(int, Object)} (but breaks List interface).
     */
    public void addTyped(int index, I object) {
        add(index, object);
    }

    public boolean addAll(int index, Collection coll) {
        Collection<O> transformed = transform((Collection<? extends I>) coll);
        return getList().addAll(index, transformed);
    }

    public ListIterator<O> listIterator() {
        return listIterator(0);
    }

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

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

    /**
     * Type-safe version of {@link #set(int, Object)} (but breaks List interface).
     */
    public O setTyped(int index, I object) {
        return set(index, object);
    }

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

    /**
     * Inner class Iterator for the TransformedList
     */
    protected class TransformedListIterator extends AbstractListIteratorDecorator {

        protected TransformedListIterator(ListIterator<O> iterator) {
            super(iterator);
        }

        public void add(Object object) {
            O transformed = transform((I) object);
            iterator.add(transformed);
        }

        public void set(Object object) {
            O transformed = transform((I) object);
            iterator.set(transformed);
        }
    }

}