Controlling a thread's processing time

Question

Hey there. I know this subject is found everywhere, but I really couldn't find an answer to my problem... yet :)
I have to support Runnable object not written by me, so I don't have access to their source code (decompiling them is not an option). So, I can't rewrite the run() method. Example:
public class MyClass extends Runnable{
  public void run(){
      sleep(10000); //sleep for 10 seconds
}I need to do something like
  new Thread(new MyClass()).start();make it run and, if it takes longer than x seconds, then stop them no matter what, even if they leave some corrupt variables.
I tried plenty of things but couldn't make it work. Pseudo code could be somthing like:
  Thread t = new Thread(new Myclass());
  t.start();
  Wait for t to terminate for 3 seconds; //note that I can't use t.wait(3000), since I can't call notify() from inside t.
  If (t didn't finalize yet)
    Kill the bastard and System.out.println("Forced to terminate!");
  else
    System.out.println("Great job!");Also, if the thread ends before the 3 seconds period, I would like not to keep waiting for the 3 seconds. That is, I don't want to call Thread.sleep(3000) after t.start();
Any piece of advise here? Thanks in advance!

Answer 1

Extending further on the defined problem if say there are multiple threads invoked
Thread threads[] = new Thread[10]
for (int = 0 , i < 10 ; i++) {
threads= new Thread();
threads[i].start();
If the main thread should wait for max X seconds would it be possible to use join(ms) or I have to do an explicit wait and then kill all alive threads in the array?
Would there be any concurrency issues related to the approach?