Getting argument type names

Question

Hi all,
I am doing a final year student project in constructing a visual tracing tool in java. I have a problem getting the method arguments and method argument types similar to problem posted before http://forum.java.sun.com/thread.jsp?forum=47&thread=200408
basically every time i track the method entry event and ask for the list of argument types i get the outmof bounds exception as if there is nothing in the method arguments. But i forced values into the arguments.They are there. I cannot understand this. I trawled through the examples and trace example with the java documentation and followed their example but still no luck. The program i'm tracing is simple on below
public class testProgram{
     private String name;
     private int age;
     public testProgram(){
          setage(22);
          setName("ciaran");
     public void setage(int theAge){
          age = theAge;
     public void setName(String theName){
          name = theName;
     public static void main(String[] args ){
          testProgram aTest = new testProgram();
the tracking code is below
     public ParseMethodData(MethodEntryEvent event){
          locEvent = (LocatableEvent) event;
          Location loc = locEvent.location();
          Method meth = loc.method();
          threadRef = locEvent.thread();
          refType = loc.declaringType();
          try{
               ArrayList list =(ArrayList) meth.argumentTypeNames();
          }catch(IndexOutOfBoundsException iobe){
               iobe.printStackTrace();
Any "general" ideas would be welcome. Why are the arguments not coming out.      

Answer 1

Hia there,
I've been looking at the jdb source code for ages now, and have had the same problems with you here. What I found was that you need to wait until a vmInterupptedEvent has been generated, otherwise you cannot access the information safely - the jvm may not have been suspended at the time that the methodentryevent was generated. This really is the case because I tested the EventHandler code in the JDB (or tty) source code. So, if you're interested in information like argument names, values and types from a methodevent, then get a list of argument type names from the method event, and when the virtual machine is suspended (i.e. a vmInterrupted event has been generated) you can safely map these to their values in the corresponding stackframe that execution is in.
There are about ten million other problems I have found with using the JDB, and stuff like that but I hope this helps. What I said worked for me, but murphy's law (most prevalent with the JDI) suggests it won't for you.
PS. So what you need to do is, implement vmInterrupted, and ensure requests are set to true for these, then use access data once this has been called.
Byee - Edd.