4fbecd2944
* java/lang/Throwable.java: Merge 1.4 support from classpath. (stackTraceBytes): Rename from stackTrace. * java/lang/Exception.java: Merge from classpath. * java/lang/StackTraceElement: New file from classpath. * gcj/javaprims.h: Rebuild CNI namespace declarations. * Makefile.am: Add StackTraceElement. * Makefile.in: Rebuilt. From-SVN: r53836
522 lines
16 KiB
Java
522 lines
16 KiB
Java
/* java.lang.Throwable -- Reference implementation of root class for
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all Exceptions and Errors
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Copyright (C) 1998, 1999, 2002 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.lang;
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import java.io.Serializable;
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import java.io.PrintWriter;
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import java.io.PrintStream;
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import java.io.ObjectOutputStream;
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import java.io.ObjectInputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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/**
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* @author Tom Tromey <tromey@cygnus.com>
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* @date October 30, 1998
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*/
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/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
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* "The Java Language Specification", ISBN 0-201-63451-1
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* Status: Sufficient for compiled code, but methods applicable to
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* bytecode not implemented. JDK 1.1.
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*/
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/* A CPlusPlusDemangler sits on top of a PrintWriter. All input is
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* passed through the "c++filt" program (part of GNU binutils) which
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* demangles internal symbols to their C++ source form.
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*
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* Closing a CPlusPlusDemangler doesn't close the underlying
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* PrintWriter; it does, however close underlying process and flush
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* all its buffers, so it's possible to guarantee that after a
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* CPlusPlusDemangler has been closed no more will ever be written to
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* the underlying PrintWriter.
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*
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* FIXME: This implictly converts data from the input stream, which is
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* a stream of characters, to a stream of bytes. We need a way of
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* handling Unicode characters in demangled identifiers. */
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class CPlusPlusDemangler extends OutputStream
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{
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java.io.OutputStream procOut;
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java.io.InputStream procIn;
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java.lang.Process proc;
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PrintWriter p;
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/* The number of bytes written to the underlying PrintWriter. This
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provides a crude but fairly portable way to determine whether or
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not the attempt to exec c++filt worked. */
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public int written = 0;
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CPlusPlusDemangler (PrintWriter writer) throws IOException
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{
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p = writer;
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proc = Runtime.getRuntime ().exec ("c++filt -s java");
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procOut = proc.getOutputStream ();
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procIn = proc.getInputStream ();
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}
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public void write (int b) throws IOException
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{
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procOut.write (b);
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while (procIn.available () != 0)
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{
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int c = procIn.read ();
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if (c == -1)
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break;
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else
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{
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p.write (c);
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written++;
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}
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}
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}
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public void close () throws IOException
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{
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procOut.close ();
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int c;
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while ((c = procIn.read ()) != -1)
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{
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p.write (c);
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written++;
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}
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p.flush ();
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try
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{
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proc.waitFor ();
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}
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catch (InterruptedException _)
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{
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}
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}
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}
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/**
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* Throwable is the superclass of all exceptions that can be raised.
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*
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* <p>There are two special cases: {@link Error} and {@link RuntimeException}:
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* these two classes (and their subclasses) are considered unchecked
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* exceptions, and are either frequent enough or catastrophic enough that you
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* do not need to declare them in <code>throws</code> clauses. Everything
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* else is a checked exception, and is ususally a subclass of
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* {@link Exception}; these exceptions have to be handled or declared.
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*
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* <p>Instances of this class are usually created with knowledge of the
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* execution context, so that you can get a stack trace of the problem spot
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* in the code. Also, since JDK 1.4, Throwables participate in "exception
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* chaining." This means that one exception can be caused by another, and
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* preserve the information of the original.
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*
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* <p>One reason this is useful is to wrap exceptions to conform to an
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* interface. For example, it would be bad design to require all levels
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* of a program interface to be aware of the low-level exceptions thrown
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* at one level of abstraction. Another example is wrapping a checked
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* exception in an unchecked one, to communicate that failure occured
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* while still obeying the method throws clause of a superclass.
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*
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* <p>A cause is assigned in one of two ways; but can only be assigned once
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* in the lifetime of the Throwable. There are new constructors added to
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* several classes in the exception hierarchy that directly initialize the
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* cause, or you can use the <code>initCause</code> method. This second
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* method is especially useful if the superclass has not been retrofitted
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* with new constructors:<br>
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* <pre>
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* try
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* {
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* lowLevelOp();
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* }
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* catch (LowLevelException lle)
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* {
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* throw (HighLevelException) new HighLevelException().initCause(lle);
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* }
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* </pre>
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* Notice the cast in the above example; without it, your method would need
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* a throws clase that declared Throwable, defeating the purpose of chainig
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* your exceptions.
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*
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* <p>By convention, exception classes have two constructors: one with no
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* arguments, and one that takes a String for a detail message. Further,
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* classes which are likely to be used in an exception chain also provide
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* a constructor that takes a Throwable, with or without a detail message
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* string.
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*
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* <p>Another 1.4 feature is the StackTrace, a means of reflection that
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* allows the program to inspect the context of the exception, and which is
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* serialized, so that remote procedure calls can correctly pass exceptions.
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*
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* @author Brian Jones
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* @author John Keiser
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* @author Mark Wielaard
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* @author Tom Tromey
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* @author Eric Blake <ebb9@email.byu.edu>
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* @since 1.0
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* @status still missing 1.4 functionality
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*/
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public class Throwable implements Serializable
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{
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/**
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* Compatible with JDK 1.0+.
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*/
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private static final long serialVersionUID = -3042686055658047285L;
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/**
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* The detail message.
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*
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* @serial specific details about the exception, may be null
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*/
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private String detailMessage;
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/**
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* The cause of the throwable, including null for an unknown or non-chained
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* cause. This may only be set once; so the field is set to
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* <code>this</code> until initialized.
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*
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* @serial the cause, or null if unknown, or this if not yet set
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* @since 1.4
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*/
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private Throwable cause = this;
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/**
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* The stack trace, in a serialized form.
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*
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* @serial the elements of the stack trace; this is non-null, and has
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* no null entries
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* @since 1.4
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*/
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// XXX Don't initialize this, once fillInStackTrace() does it.
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private StackTraceElement[] stackTrace = {};
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/**
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* Instantiate this Throwable with an empty message. The cause remains
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* uninitialized. {@link #fillInStackTrace()} will be called to set
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* up the stack trace.
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*/
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public Throwable()
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{
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this((String) null);
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}
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/**
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* Instantiate this Throwable with the given message. The cause remains
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* uninitialized. {@link #fillInStackTrace()} will be called to set
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* up the stack trace.
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*
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* @param message the message to associate with the Throwable
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*/
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public Throwable(String message)
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{
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fillInStackTrace();
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detailMessage = message;
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}
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/**
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* Instantiate this Throwable with the given message and cause. Note that
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* the message is unrelated to the message of the cause.
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* {@link #fillInStackTrace()} will be called to set up the stack trace.
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*
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* @param message the message to associate with the Throwable
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* @param cause the cause, may be null
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* @since 1.4
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*/
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public Throwable(String message, Throwable cause)
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{
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this(message);
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initCause(cause);
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}
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/**
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* Instantiate this Throwable with the given cause. The message is then
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* built as <code>cause == null ? null : cause.toString()</code>.
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* {@link #fillInStackTrace()} will be called to set up the stack trace.
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*
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* @param cause the cause, may be null
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* @since 1.4
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*/
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public Throwable(Throwable cause)
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{
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this(cause == null ? null : cause.toString(), cause);
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}
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/**
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* Get the message associated with this Throwable.
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*
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* @return the error message associated with this Throwable, may be null
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*/
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public String getMessage()
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{
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return detailMessage;
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}
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/**
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* Get a localized version of this Throwable's error message.
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* This method must be overridden in a subclass of Throwable
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* to actually produce locale-specific methods. The Throwable
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* implementation just returns getMessage().
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*
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* @return a localized version of this error message
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* @see #getMessage()
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* @since 1.1
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*/
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public String getLocalizedMessage()
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{
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return getMessage();
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}
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/**
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* Returns the cause of this exception, or null if the cause is not known
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* or non-existant. This cause is initialized by the new constructors,
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* or by calling initCause.
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*
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* @return the cause of this Throwable
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* @since 1.4
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*/
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public Throwable getCause()
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{
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return cause == this ? null : cause;
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}
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/**
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* Initialize the cause of this Throwable. This may only be called once
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* during the object lifetime, including implicitly by chaining
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* constructors.
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*
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* @param cause the cause of this Throwable, may be null
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* @return this
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* @throws IllegalArgumentException if cause is this (a Throwable can't be
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* its own cause!)
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* @throws IllegalStateException if the cause has already been set
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* @since 1.4
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*/
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public Throwable initCause(Throwable cause)
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{
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if (cause == this)
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throw new IllegalArgumentException();
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if (this.cause != this)
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throw new IllegalStateException();
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this.cause = cause;
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return this;
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}
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/**
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* Get a human-readable representation of this Throwable. The detail message
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* is retrieved by getLocalizedMessage(). Then, with a null detail
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* message, this string is simply the object's class name; otherwise
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* the string is <code>getClass().getName() + ": " + message</code>.
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*
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* @return a human-readable String represting this Throwable
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*/
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public String toString()
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{
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String msg = getLocalizedMessage();
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return getClass().getName() + (msg == null ? "" : ": " + msg);
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}
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/**
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* Print a stack trace to the standard error stream. This stream is the
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* current contents of <code>System.err</code>. The first line of output
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* is the result of {@link #toString()}, and the remaining lines represent
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* the data created by {@link #fillInStackTrace()}. While the format is
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* unspecified, this implementation uses the suggested format, demonstrated
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* by this example:<br>
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* <pre>
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* public class Junk
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* {
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* public static void main(String args[])
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* {
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* try
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* {
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* a();
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* }
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* catch(HighLevelException e)
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* {
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* e.printStackTrace();
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* }
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* }
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* static void a() throws HighLevelException
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* {
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* try
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* {
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* b();
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* }
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* catch(MidLevelException e)
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* {
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* throw new HighLevelException(e);
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* }
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* }
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* static void b() throws MidLevelException
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* {
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* c();
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* }
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* static void c() throws MidLevelException
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* {
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* try
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* {
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* d();
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* }
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* catch(LowLevelException e)
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* {
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* throw new MidLevelException(e);
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* }
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* }
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* static void d() throws LowLevelException
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* {
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* e();
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* }
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* static void e() throws LowLevelException
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* {
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* throw new LowLevelException();
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* }
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* }
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* class HighLevelException extends Exception
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* {
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* HighLevelException(Throwable cause) { super(cause); }
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* }
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* class MidLevelException extends Exception
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* {
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* MidLevelException(Throwable cause) { super(cause); }
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* }
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* class LowLevelException extends Exception
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* {
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* }
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* </pre>
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* <p>
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* <pre>
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* HighLevelException: MidLevelException: LowLevelException
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* at Junk.a(Junk.java:13)
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* at Junk.main(Junk.java:4)
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* Caused by: MidLevelException: LowLevelException
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* at Junk.c(Junk.java:23)
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* at Junk.b(Junk.java:17)
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* at Junk.a(Junk.java:11)
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* ... 1 more
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* Caused by: LowLevelException
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* at Junk.e(Junk.java:30)
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* at Junk.d(Junk.java:27)
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* at Junk.c(Junk.java:21)
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* ... 3 more
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* </pre>
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*/
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public void printStackTrace()
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{
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printStackTrace(System.err);
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}
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/**
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* Print a stack trace to the specified PrintStream. See
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* {@link #printStackTrace()} for the sample format.
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*
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* @param s the PrintStream to write the trace to
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*/
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public void printStackTrace(PrintStream s)
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{
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printStackTrace(new PrintWriter(s));
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}
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/**
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* Print a stack trace to the specified PrintWriter. See
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* {@link #printStackTrace()} for the sample format.
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*
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* @param w the PrintWriter to write the trace to
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* @since 1.1
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*/
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public void printStackTrace (PrintWriter wr)
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{
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try
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{
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CPlusPlusDemangler cPlusPlusFilter = new CPlusPlusDemangler (wr);
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PrintWriter writer = new PrintWriter (cPlusPlusFilter);
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printRawStackTrace (writer);
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writer.close ();
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if (cPlusPlusFilter.written == 0) // The demangler has failed...
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printRawStackTrace (wr);
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}
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catch (Exception e1)
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{
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printRawStackTrace (wr);
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}
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}
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/**
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* Fill in the stack trace with the current execution stack.
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*
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* @return this same throwable
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* @see #printStackTrace()
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*/
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public native Throwable fillInStackTrace();
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/**
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* Provides access to the information printed in {@link #printStackTrace()}.
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* The array is non-null, with no null entries, although the virtual
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* machine is allowed to skip stack frames. If the array is not 0-length,
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* then slot 0 holds the information on the stack frame where the Throwable
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* was created (or at least where <code>fillInStackTrace()</code> was
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* called).
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*
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* @return an array of stack trace information, as available from the VM
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* @since 1.4
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*/
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public StackTraceElement[] getStackTrace()
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{
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return stackTrace;
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}
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/**
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* Change the stack trace manually. This method is designed for remote
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* procedure calls, which intend to alter the stack trace before or after
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* serialization according to the context of the remote call.
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*
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* @param stackTrace the new trace to use
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* @throws NullPointerException if stackTrace is null or has null elements
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* @since 1.4
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*/
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public void setStackTrace(StackTraceElement[] stackTrace)
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{
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for (int i = stackTrace.length; --i >= 0; )
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if (stackTrace[i] == null)
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throw new NullPointerException();
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this.stackTrace = stackTrace;
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}
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private native final void printRawStackTrace (PrintWriter wr);
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// Setting this flag to false prevents fillInStackTrace() from running.
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static boolean trace_enabled = true;
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private transient byte stackTraceBytes[];
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}
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