001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.functors;
018
019import org.apache.commons.collections4.Closure;
020import org.apache.commons.collections4.FunctorException;
021
022/**
023 * {@link Closure} that catches any checked exception and re-throws it as a
024 * {@link FunctorException} runtime exception. Example usage:
025 *
026 * <pre>
027 * // Create a catch and re-throw closure via anonymous subclass
028 * CatchAndRethrowClosure&lt;String&gt; writer = new ThrowingClosure() {
029 *     private java.io.Writer out = // some writer
030 *
031 *     protected void executeAndThrow(String input) throws IOException {
032 *         out.write(input); // throwing of IOException allowed
033 *     }
034 * };
035 *
036 * // use catch and re-throw closure
037 * java.util.List&lt;String&gt; strList = // some list
038 * try {
039 *     CollectionUtils.forAllDo(strList, writer);
040 * } catch (FunctorException ex) {
041 *     Throwable originalError = ex.getCause();
042 *     // handle error
043 * }
044 * </pre>
045 *
046 * @param <T> the type of the input to the operation.
047 * @since 4.0
048 */
049public abstract class CatchAndRethrowClosure<T> implements Closure<T> {
050
051    /**
052     * Constructs a new instance.
053     */
054    public CatchAndRethrowClosure() {
055        // empty
056    }
057
058    /**
059     * Execute this closure on the specified input object.
060     *
061     * @param input the input to execute on
062     * @throws FunctorException (runtime) if the closure execution resulted in a
063     *             checked exception.
064     */
065    @Override
066    public void execute(final T input) {
067        try {
068            executeAndThrow(input);
069        } catch (final RuntimeException ex) {
070            throw ex;
071        } catch (final Throwable t) {
072            throw new FunctorException(t);
073        }
074    }
075
076    /**
077     * Execute this closure on the specified input object.
078     *
079     * @param input the input to execute on
080     * @throws Throwable if the closure execution resulted in a checked
081     *             exception.
082     */
083    protected abstract void executeAndThrow(T input) throws Throwable;
084}