DefaultExecutor.getWatchdog

[Narayan Singhal]

I am running a Java process using DefaultExecutor. At later time when  
user press the stop button - i want to destroy the process.

I am using:
defaultExecutor.getWatchdog().destroy();

But defaultExecutor.getWatchdog() is returning null.

How can I kill a process started using DefaultExecutor.execute??

Thanks,
Narayan