1 /* 2 * Copyright (C) 2009 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.common.testing; 18 19 import com.google.common.annotations.GwtCompatible; 20 21 import java.util.ArrayList; 22 import java.util.Collection; 23 import java.util.Collections; 24 25 /** 26 * An {@link ClusterException} is a data structure that allows for some code to 27 * "throw multiple exceptions", or something close to it. The prototypical code 28 * that calls for this class is presented below: 29 * 30 * <pre> 31 * void runManyThings(List<ThingToRun> thingsToRun) { 32 * for (ThingToRun thingToRun : thingsToRun) { 33 * thingToRun.run(); // <-- say this may throw an exception, but you want to 34 * // always run all thingsToRun 35 * } 36 * } 37 * </pre> 38 * 39 * This is what the code would become: 40 * 41 * <pre> 42 * void runManyThings(List<ThingToRun> thingsToRun) { 43 * List<Exception> exceptions = Lists.newArrayList(); 44 * for (ThingToRun thingToRun : thingsToRun) { 45 * try { 46 * thingToRun.run(); 47 * } catch (Exception e) { 48 * exceptions.add(e); 49 * } 50 * } 51 * if (exceptions.size() > 0) { 52 * throw ClusterException.create(exceptions); 53 * } 54 * } 55 * </pre> 56 * 57 * <p>See semantic details at {@link #create(Collection)}. 58 * 59 * @author Luiz-Otavio Zorzella 60 */ 61 @GwtCompatible 62 final class ClusterException extends RuntimeException { 63 64 public final Collection<? extends Throwable> exceptions; 65 ClusterException(Collection<? extends Throwable> exceptions)66 private ClusterException(Collection<? extends Throwable> exceptions) { 67 super( 68 exceptions.size() + " exceptions were thrown. The first exception is listed as a cause.", 69 exceptions.iterator().next()); 70 ArrayList<Throwable> temp = new ArrayList<Throwable>(); 71 temp.addAll(exceptions); 72 this.exceptions = Collections.unmodifiableCollection(temp); 73 } 74 75 /** 76 * @see #create(Collection) 77 */ create(Throwable... exceptions)78 public static RuntimeException create(Throwable... exceptions) { 79 ArrayList<Throwable> temp = new ArrayList<Throwable>(); 80 for (Throwable exception : exceptions) { 81 temp.add(exception); 82 } 83 return create(temp); 84 } 85 86 /** 87 * Given a collection of exceptions, returns a {@link RuntimeException}, with 88 * the following rules: 89 * 90 * <ul> 91 * <li>If {@code exceptions} has a single exception and that exception is a 92 * {@link RuntimeException}, return it 93 * <li>If {@code exceptions} has a single exceptions and that exceptions is 94 * <em>not</em> a {@link RuntimeException}, return a simple 95 * {@code RuntimeException} that wraps it 96 * <li>Otherwise, return an instance of {@link ClusterException} that wraps 97 * the first exception in the {@code exceptions} collection. 98 * </ul> 99 * 100 * <p>Though this method takes any {@link Collection}, it often makes most 101 * sense to pass a {@link java.util.List} or some other collection that 102 * preserves the order in which the exceptions got added. 103 * 104 * @throws NullPointerException if {@code exceptions} is null 105 * @throws IllegalArgumentException if {@code exceptions} is empty 106 */ create(Collection<? extends Throwable> exceptions)107 public static RuntimeException create(Collection<? extends Throwable> exceptions) { 108 if (exceptions.size() == 0) { 109 throw new IllegalArgumentException( 110 "Can't create an ExceptionCollection with no exceptions"); 111 } 112 if (exceptions.size() == 1) { 113 Throwable temp = exceptions.iterator().next(); 114 if (temp instanceof RuntimeException) { 115 return (RuntimeException)temp; 116 } else { 117 return new RuntimeException(temp); 118 } 119 } 120 return new ClusterException(exceptions); 121 } 122 } 123