    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.io;
    019
    020import java.io.IOException;
    021import java.util.Collections;
    022import java.util.Iterator;
    023import java.util.List;
    024import java.util.Objects;
    025
    026/**
    027 * An IOException based on a list of Throwable causes.
    028 * <p>
    029 * The first exception in the list is used as this exception's cause and is accessible with the usual
    030 * {@link #getCause()} while the complete list is accessible with {@link #getCauseList()}.
    031 * </p>
    032 *
    033 * @since 2.7
    034 */
    035public class IOExceptionList extends IOException implements Iterable<Throwable> {
    036
    037    private static final long serialVersionUID = 1L;
    038
    039    /**
    040     * Throws this exception if the list is not null or empty.
    041     *
    042     * @param causeList The list to test.
    043     * @param message The detail message, see {@link #getMessage()}.
    044     * @throws IOExceptionList if the list is not null or empty.
    045     * @since 2.12.0
    046     */
    047    public static void checkEmpty(final List<? extends Throwable> causeList, final Object message) throws IOExceptionList {
    048        if (!isEmpty(causeList)) {
    049            throw new IOExceptionList(Objects.toString(message, null), causeList);
    050        }
    051    }
    052
    053    private static boolean isEmpty(final List<? extends Throwable> causeList) {
    054        return size(causeList) == 0;
    055    }
    056
    057    private static int size(final List<? extends Throwable> causeList) {
    058        return causeList != null ? causeList.size() : 0;
    059    }
    060
    061    private static String toMessage(final List<? extends Throwable> causeList) {
    062        return String.format("%,d exception(s): %s", size(causeList), causeList);
    063    }
    064
    065    private final List<? extends Throwable> causeList;
    066
    067    /**
    068     * Creates a new exception caused by a list of exceptions.
    069     *
    070     * @param causeList a list of cause exceptions.
    071     */
    072    public IOExceptionList(final List<? extends Throwable> causeList) {
    073        this(toMessage(causeList), causeList);
    074    }
    075
    076    /**
    077     * Creates a new exception caused by a list of exceptions.
    078     *
    079     * @param message The detail message, see {@link #getMessage()}.
    080     * @param causeList a list of cause exceptions.
    081     * @since 2.9.0
    082     */
    083    public IOExceptionList(final String message, final List<? extends Throwable> causeList) {
    084        super(message != null ? message : toMessage(causeList), isEmpty(causeList) ? null : causeList.get(0));
    085        this.causeList = causeList == null ? Collections.emptyList() : causeList;
    086    }
    087
    088    /**
    089     * Gets the cause exception at the given index.
    090     *
    091     * @param <T> type of exception to return.
    092     * @param index index in the cause list.
    093     * @return The list of causes.
    094     */
    095    public <T extends Throwable> T getCause(final int index) {
    096        return (T) causeList.get(index);
    097    }
    098
    099    /**
    100     * Gets the cause exception at the given index.
    101     *
    102     * @param <T> type of exception to return.
    103     * @param index index in the cause list.
    104     * @param clazz type of exception to return.
    105     * @return The list of causes.
    106     */
    107    public <T extends Throwable> T getCause(final int index, final Class<T> clazz) {
    108        return clazz.cast(getCause(index));
    109    }
    110
    111    /**
    112     * Gets the cause list.
    113     *
    114     * @param <T> type of exception to return.
    115     * @return The list of causes.
    116     */
    117    public <T extends Throwable> List<T> getCauseList() {
    118        return (List<T>) causeList;
    119    }
    120
    121    /**
    122     * Works around Throwable and Generics, may fail at runtime depending on the argument value.
    123     *
    124     * @param <T> type of exception to return.
    125     * @param clazz the target type
    126     * @return The list of causes.
    127     */
    128    public <T extends Throwable> List<T> getCauseList(final Class<T> clazz) {
    129        return (List<T>) causeList;
    130    }
    131
    132    @Override
    133    public Iterator<Throwable> iterator() {
    134        return getCauseList().iterator();
    135    }
    136
    137}