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The Apache Commons Collections package contains types that extend and augment the Java Collections Framework.

There is a newer version: 4.5.0-M1

/*
 * 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.collections4.functors;

import java.io.Serializable;

import org.apache.commons.collections4.Closure;
import org.apache.commons.collections4.Transformer;

/**
 * Closure implementation that calls a Transformer using the input object
 * and ignore the result.
 *
 * @since 3.0
 */
public class TransformerClosure implements Closure, Serializable {

    /** Serial version UID */
    private static final long serialVersionUID = -5194992589193388969L;

    /** The transformer to wrap */
    private final Transformer iTransformer;

    /**
     * Factory method that performs validation.
     * 
     * A null transformer will return the NOPClosure.
     *
     * @param  the type that the closure acts on
     * @param transformer  the transformer to call, null means nop
     * @return the transformer closure
     */
    public static  Closure transformerClosure(final Transformer transformer) {
        if (transformer == null) {
            return NOPClosure.nopClosure();
        }
        return new TransformerClosure<>(transformer);
    }

    /**
     * Constructor that performs no validation.
     * Use transformerClosure if you want that.
     *
     * @param transformer  the transformer to call, not null
     */
    public TransformerClosure(final Transformer transformer) {
        super();
        iTransformer = transformer;
    }

    /**
     * Executes the closure by calling the decorated transformer.
     *
     * @param input  the input object
     */
    @Override
    public void execute(final E input) {
        iTransformer.transform(input);
    }

    /**
     * Gets the transformer.
     *
     * @return the transformer
     * @since 3.1
     */
    public Transformer getTransformer() {
        return iTransformer;
    }

}