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JSF components and utilities that can be used with any JSF implementation. This library is based on the JSF1.1 version of Tomahawk, but with minor source code and build changes to take advantage of JSF1.2 features. A JSF1.2 implementation is required to use this version of the Tomahawk library.

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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.myfaces.shared_tomahawk.util;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

/**
 * Various helpers to deal with exception
 * 
 * @author [email protected]
 */
public final class ExceptionUtils
{
    private ExceptionUtils()
    {
    }

    /**
     * 
     * returns a list of all throwables (including the one you passed in) wrapped by the given throwable.
     * In contrast to a simple call to getClause() on each throwable it will also check if the throwable class
     * contain a method getRootCause() (e.g. ServletException or JspException) and call it instead.
     * 
     * 
     * The first list element will your passed in exception, the last list element is the cause. 
     * 
     */
    public static List getExceptions(Throwable cause)
    {
        List exceptions = new ArrayList(10);
        exceptions.add(cause);
        
        do
        {
            Throwable nextCause;
            try
            {
                Method rootCause = cause.getClass().getMethod("getRootCause", new Class[]{});
                nextCause = (Throwable) rootCause.invoke(cause, new Object[]{});
            }
            catch(Exception e)
            {
                nextCause = cause.getCause();
            }
            if (cause == nextCause)
            {
                break;
            }
            
            if (nextCause != null)
            {
                exceptions.add(nextCause);
            }
            
            cause = nextCause;
        }
        while (cause != null);
        
        return exceptions;
    }

    /**
     * Find a throwable message starting with the last element.

     * Returns the first throwable message where throwable.getMessage() != null 
     */
    public static String getExceptionMessage(List throwables)
    {
        if (throwables == null)
        {
            return null;
        }

        for (int i = throwables.size()-1; i>0; i--)
        {
            Throwable t = (Throwable) throwables.get(i);
            if (t.getMessage() != null)
            {
                return t.getMessage();
            }
        }
        
        return null;
    }
}