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 import java.util.ArrayList; 21 import java.util.Arrays; 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 "throw multiple 27 * exceptions", or something close to it. The prototypical code that calls for this class is 28 * presented below: 29 * 30 * <pre> 31 * void runManyThings({@literal 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 * <p>This is what the code would become: 40 * 41 * <pre> 42 * void runManyThings({@literal List<ThingToRun>} thingsToRun) { 43 * {@literal 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<>(exceptions); 71 this.exceptions = Collections.unmodifiableCollection(temp); 72 } 73 74 /** @see #create(Collection) */ create(Throwable... exceptions)75 public static RuntimeException create(Throwable... exceptions) { 76 ArrayList<Throwable> temp = new ArrayList<>(Arrays.asList(exceptions)); 77 return create(temp); 78 } 79 80 /** 81 * Given a collection of exceptions, returns a {@link RuntimeException}, with the following rules: 82 * 83 * <ul> 84 * <li>If {@code exceptions} has a single exception and that exception is a {@link 85 * RuntimeException}, return it 86 * <li>If {@code exceptions} has a single exceptions and that exceptions is <em>not</em> a 87 * {@link RuntimeException}, return a simple {@code RuntimeException} that wraps it 88 * <li>Otherwise, return an instance of {@link ClusterException} that wraps the first exception 89 * in the {@code exceptions} collection. 90 * </ul> 91 * 92 * <p>Though this method takes any {@link Collection}, it often makes most sense to pass a {@link 93 * java.util.List} or some other collection that preserves the order in which the exceptions got 94 * added. 95 * 96 * @throws NullPointerException if {@code exceptions} is null 97 * @throws IllegalArgumentException if {@code exceptions} is empty 98 */ create(Collection<? extends Throwable> exceptions)99 public static RuntimeException create(Collection<? extends Throwable> exceptions) { 100 if (exceptions.size() == 0) { 101 throw new IllegalArgumentException("Can't create an ExceptionCollection with no exceptions"); 102 } 103 if (exceptions.size() == 1) { 104 Throwable temp = exceptions.iterator().next(); 105 if (temp instanceof RuntimeException) { 106 return (RuntimeException) temp; 107 } else { 108 return new RuntimeException(temp); 109 } 110 } 111 return new ClusterException(exceptions); 112 } 113 } 114