home | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Commons Collections example source code file (ChainedTransformer.java)

This example Commons Collections source code file (ChainedTransformer.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

chainedtransformer, chainedtransformer, illegalargumentexception, illegalargumentexception, io, iterator, object, object, serializable, transformer, transformer, transformers, util

The Commons Collections ChainedTransformer.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.functors;

import java.io.Serializable;
import java.util.Collection;
import java.util.Iterator;

import org.apache.commons.collections.Transformer;

/**
 * Transformer implementation that chains the specified transformers together.
 * <p>
 * The input object is passed to the first transformer. The transformed result
 * is passed to the second transformer and so on.
 * 
 * @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 ChainedTransformer implements Transformer, Serializable {

    /** Serial version UID */
    private static final long serialVersionUID = 3514945074733160196L;

    /** The transformers to call in turn */
    private final Transformer[] iTransformers;

    /**
     * Factory method that performs validation and copies the parameter array.
     * 
     * @param transformers  the transformers to chain, copied, no nulls
     * @return the <code>chained transformer
     * @throws IllegalArgumentException if the transformers array is null
     * @throws IllegalArgumentException if any transformer in the array is null
     */
    public static Transformer getInstance(Transformer[] transformers) {
        FunctorUtils.validate(transformers);
        if (transformers.length == 0) {
            return NOPTransformer.INSTANCE;
        }
        transformers = FunctorUtils.copy(transformers);
        return new ChainedTransformer(transformers);
    }
    
    /**
     * Create a new Transformer that calls each transformer in turn, passing the 
     * result into the next transformer. The ordering is that of the iterator()
     * method on the collection.
     * 
     * @param transformers  a collection of transformers to chain
     * @return the <code>chained transformer
     * @throws IllegalArgumentException if the transformers collection is null
     * @throws IllegalArgumentException if any transformer in the collection is null
     */
    public static Transformer getInstance(Collection transformers) {
        if (transformers == null) {
            throw new IllegalArgumentException("Transformer collection must not be null");
        }
        if (transformers.size() == 0) {
            return NOPTransformer.INSTANCE;
        }
        // convert to array like this to guarantee iterator() ordering
        Transformer[] cmds = new Transformer[transformers.size()];
        int i = 0;
        for (Iterator it = transformers.iterator(); it.hasNext();) {
            cmds[i++] = (Transformer) it.next();
        }
        FunctorUtils.validate(cmds);
        return new ChainedTransformer(cmds);
    }

    /**
     * Factory method that performs validation.
     * 
     * @param transformer1  the first transformer, not null
     * @param transformer2  the second transformer, not null
     * @return the <code>chained transformer
     * @throws IllegalArgumentException if either transformer is null
     */
    public static Transformer getInstance(Transformer transformer1, Transformer transformer2) {
        if (transformer1 == null || transformer2 == null) {
            throw new IllegalArgumentException("Transformers must not be null");
        }
        Transformer[] transformers = new Transformer[] { transformer1, transformer2 };
        return new ChainedTransformer(transformers);
    }

    /**
     * Constructor that performs no validation.
     * Use <code>getInstance if you want that.
     * 
     * @param transformers  the transformers to chain, not copied, no nulls
     */
    public ChainedTransformer(Transformer[] transformers) {
        super();
        iTransformers = transformers;
    }

    /**
     * Transforms the input to result via each decorated transformer
     * 
     * @param object  the input object passed to the first transformer
     * @return the transformed result
     */
    public Object transform(Object object) {
        for (int i = 0; i < iTransformers.length; i++) {
            object = iTransformers[i].transform(object);
        }
        return object;
    }

    /**
     * Gets the transformers, do not modify the array.
     * @return the transformers
     * @since Commons Collections 3.1
     */
    public Transformer[] getTransformers() {
        return iTransformers;
    }

}

Other Commons Collections examples (source code examples)

Here is a short list of links related to this Commons Collections ChainedTransformer.java source code file:

new blog posts

 

Copyright 1998-2016 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.