Get to the base exception (if any) - Java java.lang

Java examples for java.lang:Throwable

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Description

Get to the base exception (if any)

Demo Code

/*/*ww  w . j a v a  2  s .  co m*/
 *
 *  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 com.java2s;

import java.lang.reflect.Method;

import java.lang.reflect.InvocationTargetException;

public class Main {
    /**
     * List of no-arg methods that are known to return a wrapped throwable
     **/
    private static final String[] unwrapMethods = { "getRootCause",
            "getTargetException", "getTargetError", "getException",
            "getCausedByException", "getLinkedException" };

    /**
     * Get to the base exception (if any)
     */
    public static Throwable baseException(Throwable t) {
        Throwable wrapped = wrappedException(t);
        if (wrapped != null)
            return baseException(wrapped);
        else
            return t;
    }

    public static Throwable wrappedException(Throwable t) {
        // handle these statically since they are core to Java
        if (t instanceof InvocationTargetException) {
            return ((InvocationTargetException) t).getTargetException();
        }

        return getRootCauseWithReflection(t);
    }

    private static Throwable getRootCauseWithReflection(Throwable t) {
        for (int i = 0; i < unwrapMethods.length; i++) {
            Method m = null;

            try {
                m = t.getClass()
                        .getMethod(unwrapMethods[i], (Class[]) null);
                return (Throwable) m.invoke(t, (Object[]) null);
            } catch (Exception nsme) {
                // ignore
            }
        }

        return null;
    }
}

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