Hello,

I'm working on a project which consists of a java layer and a C++ library which we build as a shared object on Linux. The java code accesses the Shared Object via JNI. We port the native stuff to several platforms including RedHat Linux and Windows. In the Developer Studio on Windows I can set a breakpoint in one of the C++ files and then direct the debugger to launch the calling Java process. I'd really like to be able to debug the native portion on Linux but I can't seem to make it work with gdb. Is it possible, then, to debug a shared object using gdb by launching a java process? Thanks in advance for any replies.

-exits

Short answer: yes
Long answer:

- start gdb
- make gdb stop whenever any shared library is loaded
(gdb) set stop-on-solib 1
- run your java application with arguments
(gdb) file java
(gdb) set args ... MyClass
(gdb) run
- whenever gdb stops, check whether your JNI library
has been loaded
(gdb) info shared
- if JNI library is not on the above list, do continue
- if JNI library is on the above list, issue a breakpoint
(gdb) break Java_MyClass_....
(gdb) continue
- you are now inside JNI route debugging it with GDB

Thanks Stanley! That worked great.

Hi,
I was viewing postings related to JNi and found that it is similar to what I am doing.

I you don't mind, take a look at teh problem described below, and tell me how to access my shared C++ library that is accessed via JNI calls from JAVA.

Thanks,

Here is the problem description:


Operating system: Red Hat Linux 2.4.21-4.EL.
GUI interface: GNOME

I am writing a JAVA JNI program using JDK 1.5.0_04 version and netbeans 4.1 IDE. I am trying to access a shared library called "libdfa.so" that was written in GCC compiler.

I have placed this "libdfa.so" library in the JAVA CLASSPATH

I used the statement : System.loadLibrary("dfa");

- when I run the program from within netbeans, I get the error message :

Exception in thread "main" java.lang.UnsatisfiedLinkError: no dfa in
java.library.path.

* Is there any more environment varaibales I need to set ?

* Where do I place my "libdfa.so"?

* Is this the right syntax?

- Using GUI Natutilus 2.2.4 ( a graphical shell for GNOME), I tried to run
The jar file by double clicking on it, and nothing happens. It won't run.

* How do I run it from the GUI session?



Thanks in advance.

Sabliny.