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Commons Collections example source code file (TransformedPredicate.java)

This example Commons Collections source code file (TransformedPredicate.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

illegalargumentexception, illegalargumentexception, io, object, predicate, predicate, predicatedecorator, serializable, the, the, transformedpredicate, transformedpredicate, transformer

The Commons Collections TransformedPredicate.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 org.apache.commons.collections.Predicate;
import org.apache.commons.collections.Transformer;

/**
 * Predicate implementation that transforms the given object before invoking
 * another <code>Predicate.
 * 
 * @since Commons Collections 3.1
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
 * @author Alban Peignier
 * @author Stephen Colebourne
 */
public final class TransformedPredicate implements Predicate, PredicateDecorator, Serializable {

    /** Serial version UID */
    private static final long serialVersionUID = -5596090919668315834L;
    
    /** The transformer to call */
    private final Transformer iTransformer;
    /** The predicate to call */
    private final Predicate iPredicate;

    /**
     * Factory to create the predicate.
     * 
     * @param transformer  the transformer to call
     * @param predicate  the predicate to call with the result of the transform
     * @return the predicate
     * @throws IllegalArgumentException if the transformer or the predicate is null
     */
    public static Predicate getInstance(Transformer transformer, Predicate predicate) {
        if (transformer == null) {
            throw new IllegalArgumentException("The transformer to call must not be null");
        }
        if (predicate == null) {
            throw new IllegalArgumentException("The predicate to call must not be null");
        }
        return new TransformedPredicate(transformer, predicate);
    }

    /**
     * Constructor that performs no validation.
     * Use <code>getInstance if you want that.
     * 
     * @param transformer  the transformer to use
     * @param predicate  the predicate to decorate
     */
    public TransformedPredicate(Transformer transformer, Predicate predicate) {
        iTransformer = transformer;
        iPredicate = predicate;
    }
    
    /**
     * Evaluates the predicate returning the result of the decorated predicate
     * once the input has been transformed
     * 
     * @param object  the input object which will be transformed
     * @return true if decorated predicate returns true
     */
    public boolean evaluate(Object object) {
        Object result = iTransformer.transform(object);
        return iPredicate.evaluate(result);
    }

    /**
     * Gets the predicate being decorated.
     * 
     * @return the predicate as the only element in an array
     * @since Commons Collections 3.1
     */
    public Predicate[] getPredicates() {
        return new Predicate[] {iPredicate};
    }

    /**
     * Gets the transformer in use.
     * 
     * @return the transformer
     */
    public Transformer getTransformer() {
        return iTransformer;
    }

}

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