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.classification.InterfaceAudience; 022 import org.apache.hadoop.lib.util.Check; 023 024 import java.util.concurrent.Callable; 025 026 /** 027 * Adapter class that allows <code>Runnable</code>s and <code>Callable</code>s to 028 * be treated as the other. 029 */ 030 @InterfaceAudience.Private 031 public class RunnableCallable implements Callable<Void>, Runnable { 032 private Runnable runnable; 033 private Callable<?> callable; 034 035 /** 036 * Constructor that takes a runnable. 037 * 038 * @param runnable runnable. 039 */ 040 public RunnableCallable(Runnable runnable) { 041 this.runnable = Check.notNull(runnable, "runnable"); 042 } 043 044 /** 045 * Constructor that takes a callable. 046 * 047 * @param callable callable. 048 */ 049 public RunnableCallable(Callable<?> callable) { 050 this.callable = Check.notNull(callable, "callable"); 051 } 052 053 /** 054 * Invokes the wrapped callable/runnable as a callable. 055 * 056 * @return void 057 * 058 * @throws Exception thrown by the wrapped callable/runnable invocation. 059 */ 060 @Override 061 public Void call() throws Exception { 062 if (runnable != null) { 063 runnable.run(); 064 } else { 065 callable.call(); 066 } 067 return null; 068 } 069 070 /** 071 * Invokes the wrapped callable/runnable as a runnable. 072 * 073 * @throws RuntimeException thrown by the wrapped callable/runnable invocation. 074 */ 075 @Override 076 public void run() { 077 if (runnable != null) { 078 runnable.run(); 079 } else { 080 try { 081 callable.call(); 082 } catch (Exception ex) { 083 throw new RuntimeException(ex); 084 } 085 } 086 } 087 088 /** 089 * Returns the class name of the wrapper callable/runnable. 090 * 091 * @return the class name of the wrapper callable/runnable. 092 */ 093 public String toString() { 094 return (runnable != null) ? runnable.getClass().getSimpleName() : callable.getClass().getSimpleName(); 095 } 096 }