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java/org/apache/tomcat/util/MultiThrowable.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.apache.tomcat.util;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Wraps a list of throwables as a single throwable. This is intended to be used
+ * when multiple actions are taken where each may throw an exception but all
+ * actions are taken before any errors are reported.
+ * <p>
+ * This class is <b>NOT</b> threadsafe.
+ */
+public class MultiThrowable extends Throwable {
+
+    private static final long serialVersionUID = 1L;
+
+    private List<Throwable> throwables = new ArrayList<>();
+
+    /**
+     * Add a throwable to the list of wrapped throwables.
+     *
+     * @param t The throwable to add
+     */
+    public void add(Throwable t) {
+        throwables.add(t);
+    }
+
+
+    /**
+     * @return A read-only list of the wrapped throwables.
+     */
+    public List<Throwable> getThrowables() {
+        return Collections.unmodifiableList(throwables);
+    }
+
+
+    /**
+     * @return {@code null} if there are no wrapped throwables, the Throwable if
+     *         there is a single wrapped throwable or the current instance of
+     *         there are multiple wrapped throwables
+     */
+    public Throwable getThrowable() {
+        if (size() == 0) {
+            return null;
+        } else if (size() == 1) {
+            return throwables.get(0);
+        } else {
+            return this;
+        }
+    }
+
+
+    /**
+     * @return The number of throwables currently wrapped by this instance.
+     */
+    public int size() {
+        return throwables.size();
+    }
+
+
+    /**
+     * Overrides the default implementation to provide a concatenation of the
+     * messages associated with each of the wrapped throwables. Note that the
+     * format of the returned String is not guaranteed to be fixed and may
+     * change in a future release.
+     */
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append(super.toString());
+        sb.append(": ");
+        sb.append(size());
+        sb.append(" wrapped Throwables: ");
+        for (Throwable t : throwables) {
+            sb.append("[");
+            sb.append(t.getMessage());
+            sb.append("]");
+        }
+
+        return sb.toString();
+    }
+}