StepEvent with main thread

I'm trying to implement the Trace program in the demo jpda,

how should I build this stepEvent? Since the constructor is

EventRequestManager mgr = vm.eventRequestManager();

StepRequest req = mgr.createStepRequest([b]thread[/b],StepRequest.STEP_MIN,StepRequest.STEP_INTO);

what shoud thethread be? since I need to trace all lines executed by the class I passed to the Trace program, how can I get the threadReference to the one that is executing the class?

[495 byte] By [xa_l_ix] at [2007-9-30 16:35:58]