michael@0: /*
michael@0:  * ====================================================================
michael@0:  * Licensed to the Apache Software Foundation (ASF) under one
michael@0:  * or more contributor license agreements.  See the NOTICE file
michael@0:  * distributed with this work for additional information
michael@0:  * regarding copyright ownership.  The ASF licenses this file
michael@0:  * to you under the Apache License, Version 2.0 (the
michael@0:  * "License"); you may not use this file except in compliance
michael@0:  * with the License.  You may obtain a copy of the License at
michael@0:  *
michael@0:  *   http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  * Unless required by applicable law or agreed to in writing,
michael@0:  * software distributed under the License is distributed on an
michael@0:  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
michael@0:  * KIND, either express or implied.  See the License for the
michael@0:  * specific language governing permissions and limitations
michael@0:  * under the License.
michael@0:  * ====================================================================
michael@0:  *
michael@0:  * This software consists of voluntary contributions made by many
michael@0:  * individuals on behalf of the Apache Software Foundation.  For more
michael@0:  * information on the Apache Software Foundation, please see
michael@0:  * <http://www.apache.org/>.
michael@0:  *
michael@0:  */
michael@0: package ch.boye.httpclientandroidlib.util;
michael@0: 
michael@0: import java.lang.reflect.Method;
michael@0: 
michael@0: /**
michael@0:  * The home for utility methods that handle various exception-related tasks.
michael@0:  *
michael@0:  *
michael@0:  * @since 4.0
michael@0:  */
michael@0: public final class ExceptionUtils {
michael@0: 
michael@0:     /** A reference to Throwable's initCause method, or null if it's not there in this JVM */
michael@0:     static private final Method INIT_CAUSE_METHOD = getInitCauseMethod();
michael@0: 
michael@0:     /**
michael@0:      * Returns a <code>Method<code> allowing access to
michael@0:      * {@link Throwable#initCause(Throwable) initCause} method of {@link Throwable},
michael@0:      * or <code>null</code> if the method
michael@0:      * does not exist.
michael@0:      *
michael@0:      * @return A <code>Method<code> for <code>Throwable.initCause</code>, or
michael@0:      * <code>null</code> if unavailable.
michael@0:      */
michael@0:     static private Method getInitCauseMethod() {
michael@0:         try {
michael@0:             Class[] paramsClasses = new Class[] { Throwable.class };
michael@0:             return Throwable.class.getMethod("initCause", paramsClasses);
michael@0:         } catch (NoSuchMethodException e) {
michael@0:             return null;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * If we're running on JDK 1.4 or later, initialize the cause for the given throwable.
michael@0:      *
michael@0:      * @param  throwable The throwable.
michael@0:      * @param  cause     The cause of the throwable.
michael@0:      */
michael@0:     public static void initCause(Throwable throwable, Throwable cause) {
michael@0:         if (INIT_CAUSE_METHOD != null) {
michael@0:             try {
michael@0:                 INIT_CAUSE_METHOD.invoke(throwable, new Object[] { cause });
michael@0:             } catch (Exception e) {
michael@0:                 // Well, with no logging, the only option is to munch the exception
michael@0:             }
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     private ExceptionUtils() {
michael@0:     }
michael@0: 
michael@0: }