1 /*
   2  * Copyright (c) 1998, 1999, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.jdi.event;
  27 
  28 import com.sun.jdi.*;
  29 
  30 /**
  31  * Notification of an exception in the target VM. When an exception
  32  * is thrown which satisfies a currently enabled
  33  * {@link com.sun.jdi.request.ExceptionRequest exception request},
  34  * an {@link EventSet event set}
  35  * containing an instance of this class will be added
  36  * to the VM's event queue.
  37  * If the exception is thrown from a non-native method,
  38  * the exception event is generated at the location where the
  39  * exception is thrown.
  40  * If the exception is thrown from a native method, the exception event
  41  * is generated at the first non-native location reached after the exception
  42  * is thrown.
  43  *
  44  * @author Robert Field
  45  * @since  1.3
  46  */
  47 public interface ExceptionEvent extends LocatableEvent {
  48 
  49     /**
  50      * Gets the thrown exception object. The exception object is
  51      * an instance of {@link java.lang.Throwable} or a subclass in the
  52      * target VM.
  53      *
  54      * @return an {@link ObjectReference} which mirrors the thrown object in
  55      * the target VM.
  56      */
  57     public ObjectReference exception();
  58 
  59     /**
  60      * Gets the location where the exception will be caught. An exception
  61      * is considered to be caught if, at the point of the throw, the
  62      * current location is dynamically enclosed in a try statement that
  63      * handles the exception. (See the JVM specification for details).
  64      * If there is such a try statement, the catch location is the
  65      * first code index of the appropriate catch clause.
  66      * <p>
  67      * If there are native methods in the call stack at the time of the
  68      * exception, there are important restrictions to note about the
  69      * returned catch location. In such cases,
  70      * it is not possible to predict whether an exception will be handled
  71      * by some native method on the call stack.
  72      * Thus, it is possible that exceptions considered uncaught
  73      * here will, in fact, be handled by a native method and not cause
  74      * termination of the target VM. Furthermore, it cannot be assumed that the
  75      * catch location returned here will ever be reached by the throwing
  76      * thread. If there is
  77      * a native frame between the current location and the catch location,
  78      * the exception might be handled and cleared in that native method
  79      * instead.
  80      * <p>
  81      * Note that the compiler can generate try-catch blocks in some cases
  82      * where they are not explicit in the source code; for example,
  83      * the code generated for <code>synchronized</code> and
  84      * <code>finally</code> blocks can contain implicit try-catch blocks.
  85      * If such an implicitly generated try-catch is
  86      * present on the call stack at the time of the throw, the exception
  87      * will be considered caught even though it appears to be uncaught from
  88      * examination of the source code.
  89      *
  90      * @return the {@link Location} where the exception will be caught or null if
  91      * the exception is uncaught.
  92      */
  93     public Location catchLocation();
  94 }