JTrek 1.1 From Compaq

Question

hi! I am using JTrek 1.1, a Java instrumentation tool that enables you to write Java applications that examine and modify Java classfiles. I was hoping someone might have experience and/or knowledge about it? I need some help with an exception I am getting when I try to call .passStack().
Also, maybe others can help me with this Java Exception I get? (It happens when I try to call .passStack(): I want to communicate the arguments of a method I am trying to monitor...but I can't seem to do it and get this Exception :( :
Exception in thread "main" java.lang.VerifyError: (class: permissions, method: openFile signature: (Ljava/lang/String;)Ljava/lang/String;) Expecting to find object/array on stack
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:140)
        at mac.MaCMain.main(MaCMain.java:41)Any ideas? I have been surfing on the Web and I wonder if I am encountering a bug in the JVM? I am using JDK 1.3 . Hmmm?
Further, with the call to new FileInputStream(filename) to open a file, is the filename argument put onto the run-time stack at the instruction "invokespecial FileInputStream"? Is not the run-time stack structured:
top-element to bottom-element:
0. object reference
1. ... method arguments
*thank you!

Answer 1

Errors like these tend to mean that a piece of code was compiled for a different version of the method than it thinks is there.
Suppose I made a method like this in one class
public void foo( String s )
and called it from another class like this
a.foo( "Hello" );
I compiled it all. Then i went back and changed foo to be
public void foo( String s, int i )
compiled it, but didn't compile the call (a.foo("Hello"))
These are the kinds of errors you would see, i believe.
It's possible that compaq just foobar'ed the jar file.