Name: yyT116575			Date: 11/14/2000


java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0)
Java HotSpot(TM) Client VM (build 1.3.0, mixed mode)

When coupling Java and C++ by means of the JNI, I faced the following problem.
A Java program calls a native C++ method through the JNI. This C++ method throws
an exception and also catches it again. So, the exception does NOT propagate
from the C++ side to the Java side; it remains on the C++ side. Nevertheless,
the JVM complains about an unexpected exception in the native code.

By the way, this is not a problem with jdk1.3 in a Solaris environment.



How to reproduce the problem:
=============================

(1) javac TestExceptions.java

(2) javah TestExceptions

(3) g++ -o libtestx.so -fPIC -shared <jni headers> TestExceptions.C

    where <jni headers> is
    -I/usr/local/jdk1.3/include -I/usr/local/jdk1.3/include/linux
    if you installed jdk under /usr/local
 
(4) Prepend the directory containing libtestx.so (built in step (3))
    to the environment variable LD_LIBRARY_PATH

(5) java TestExceptions


Faulty output:
--------------

Boring non-3
MyException thrown!
# # An unexpected exception has been detected in native code outside the VM.#
  Program counter=0x406494ea
#
# Problematic Thread: prio=1 tid=0x804e328 nid=0x66f runnable
#


Correct output:
---------------

Boring non-3
MyException thrown!
MyException caught!
Exceptional 3
Boring non-3


Files:
------

// *** File: TestExceptions.java ***
public class TestExceptions {

  private native String threeIsOdd(int number);

  static {
	System.loadLibrary("testx");
  }

  public static void main(String[] args) {
	TestExceptions tx = new TestExceptions();
	for (int i = 2; i < 5; i++) {
	  System.out.println(tx.threeIsOdd(i));
	}
  }
}



// *** File: TestExceptions.C ***
#include <iostream>

#include "TestExceptions.h"

class MyException {
public:
  MyException() {}
  ~MyException() {}
};


JNIEXPORT jstring JNICALL
Java_TestExceptions_threeIsOdd(JNIEnv* env, jobject, jint number)
{
  try {
	if (number == 3) {
	  cout << "MyException thrown!" << endl;
	  throw MyException();
	}
	return env->NewStringUTF("Boring non-3");
  }
  catch (MyException&) {
	cout << "MyException caught!" << endl;
	return env->NewStringUTF("Exceptional 3");
  }
  catch (...) {
	cout << "OtherException caught!" << endl;
  }

  return env->NewStringUTF("Should not be reached");
}
(Review ID: 112220) 
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