001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019 package org.apache.hadoop.lib.lang; 020 021 import org.apache.hadoop.lib.util.Check; 022 023 import java.util.concurrent.Callable; 024 025 /** 026 * Adapter class that allows <code>Runnable</code>s and <code>Callable</code>s to 027 * be treated as the other. 028 */ 029 public class RunnableCallable implements Callable<Void>, Runnable { 030 private Runnable runnable; 031 private Callable<?> callable; 032 033 /** 034 * Constructor that takes a runnable. 035 * 036 * @param runnable runnable. 037 */ 038 public RunnableCallable(Runnable runnable) { 039 this.runnable = Check.notNull(runnable, "runnable"); 040 } 041 042 /** 043 * Constructor that takes a callable. 044 * 045 * @param callable callable. 046 */ 047 public RunnableCallable(Callable<?> callable) { 048 this.callable = Check.notNull(callable, "callable"); 049 } 050 051 /** 052 * Invokes the wrapped callable/runnable as a callable. 053 * 054 * @return void 055 * 056 * @throws Exception thrown by the wrapped callable/runnable invocation. 057 */ 058 @Override 059 public Void call() throws Exception { 060 if (runnable != null) { 061 runnable.run(); 062 } else { 063 callable.call(); 064 } 065 return null; 066 } 067 068 /** 069 * Invokes the wrapped callable/runnable as a runnable. 070 * 071 * @throws RuntimeException thrown by the wrapped callable/runnable invocation. 072 */ 073 @Override 074 public void run() { 075 if (runnable != null) { 076 runnable.run(); 077 } else { 078 try { 079 callable.call(); 080 } catch (Exception ex) { 081 throw new RuntimeException(ex); 082 } 083 } 084 } 085 086 /** 087 * Returns the class name of the wrapper callable/runnable. 088 * 089 * @return the class name of the wrapper callable/runnable. 090 */ 091 public String toString() { 092 return (runnable != null) ? runnable.getClass().getSimpleName() : callable.getClass().getSimpleName(); 093 } 094 }