1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.io;
19
20 import java.io.IOException;
21 import java.util.ArrayList;
22 import java.util.Collections;
23 import java.util.Iterator;
24 import java.util.List;
25 import java.util.Objects;
26
27 /**
28 * An IOException based on a list of Throwable causes.
29 * <p>
30 * The first exception in the list is used as this exception's cause and is accessible with the usual
31 * {@link #getCause()} while the complete list is accessible with {@link #getCauseList()}.
32 * </p>
33 *
34 * @since 2.7
35 */
36 public class IOExceptionList extends IOException implements Iterable<Throwable> {
37
38 private static final long serialVersionUID = 1L;
39
40 /**
41 * Throws this exception if the list is not null or empty.
42 *
43 * @param causeList The list to test.
44 * @param message The detail message, see {@link #getMessage()}.
45 * @throws IOExceptionList if the list is not null or empty.
46 * @since 2.12.0
47 */
48 public static void checkEmpty(final List<? extends Throwable> causeList, final Object message) throws IOExceptionList {
49 if (!isEmpty(causeList)) {
50 throw new IOExceptionList(Objects.toString(message, null), causeList);
51 }
52 }
53
54 private static boolean isEmpty(final List<? extends Throwable> causeList) {
55 return size(causeList) == 0;
56 }
57
58 private static int size(final List<? extends Throwable> causeList) {
59 return causeList != null ? causeList.size() : 0;
60 }
61
62 private static String toMessage(final List<? extends Throwable> causeList) {
63 return String.format("%,d exception(s): %s", size(causeList), causeList);
64 }
65
66 /**
67 * List of causes.
68 */
69 private final List<? extends Throwable> causeList;
70
71 /**
72 * Constructs a new exception caused by a list of exceptions.
73 *
74 * @param causeList a list of cause exceptions.
75 */
76 public IOExceptionList(final List<? extends Throwable> causeList) {
77 this(toMessage(causeList), causeList);
78 }
79
80 /**
81 * Constructs a new exception caused by a list of exceptions.
82 *
83 * @param message The detail message, see {@link #getMessage()}.
84 * @param causeList a list of cause exceptions.
85 * @since 2.9.0
86 */
87 public IOExceptionList(final String message, final List<? extends Throwable> causeList) {
88 super(message != null ? message : toMessage(causeList), isEmpty(causeList) ? null : causeList.get(0));
89 this.causeList = causeList == null ? Collections.emptyList() : causeList;
90 }
91
92 /**
93 * Gets the cause exception at the given index.
94 *
95 * @param <T> type of exception to return.
96 * @param index index in the cause list.
97 * @return The list of causes.
98 */
99 public <T extends Throwable> T getCause(final int index) {
100 return (T) causeList.get(index);
101 }
102
103 /**
104 * Gets the cause exception at the given index.
105 *
106 * @param <T> type of exception to return.
107 * @param index index in the cause list.
108 * @param clazz type of exception to return.
109 * @return The list of causes.
110 */
111 public <T extends Throwable> T getCause(final int index, final Class<T> clazz) {
112 return clazz.cast(getCause(index));
113 }
114
115 /**
116 * Gets the cause list.
117 *
118 * @param <T> type of exception to return.
119 * @return The list of causes.
120 */
121 public <T extends Throwable> List<T> getCauseList() {
122 return (List<T>) new ArrayList<>(causeList);
123 }
124
125 /**
126 * Works around Throwable and Generics, may fail at runtime depending on the argument value.
127 *
128 * @param <T> type of exception to return.
129 * @param clazz the target type
130 * @return The list of causes.
131 */
132 public <T extends Throwable> List<T> getCauseList(final Class<T> clazz) {
133 return (List<T>) new ArrayList<>(causeList);
134 }
135
136 @Override
137 public Iterator<Throwable> iterator() {
138 return getCauseList().iterator();
139 }
140
141 }