[prog] Java exceptions: finding out the source

[Mary]

Hi folks,

I'm trying to run someone else's Java program. I've programmed in Java
but I'm by no means an expert, especially when it comes to interaction
between Java and the operating system.

I have access to the code I am trying to run and I'm willing to change
it, but I would appreciate help with getting better error messages.

Somewhere in the code, this exception is being produced:

    Exception in thread "main"

That's the complete error message: no line number, no indication about
what type of Exception was produced, nothing. Further, there's no line
break after that error, I get:

    Exception in thread "main" mary at flay

where "mary at flay" is my bash prompt. I know which line of the code is
producing the error (I just binary searched with print statements) but I
don't have a complete call stack, I only have this very unhelpful error
message.

Any ideas?

-Mary