How to simulate an unhandled exception in Java

Question

I am creating some multi-threaded code, and I have created a JobDispatcher class that creates threads. I want this object to handle any unhandled exceptions in the worker threads, and so I am using

Thread.setUncaughtExceptionHandler(this);

Now, I would like to test this functionality - how can I generate an unhandled exception in the run() method of my worker object?

Answer 1

Just throw any exception.

E.g.:

throw new RuntimeException("Testing unhandled exception processing.");

Complete:

public class RuntimeTest
{
  public static void main(String[] a)
  {
    Thread t = new Thread()
    {
      public void run()
      {
        throw new RuntimeException("Testing unhandled exception processing.");
      }
    };
    t.setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler()
    {
      public void uncaughtException(Thread t, Throwable e)
      {
        System.err.println(t + "; " + e);
      }
    });
    t.start();
  }
}

Answer 2

What's the problem with just throwing an exception:

throw new Exception("This should be unhandled");

Inside your run method. And of course, not catching it. It should trigger your handler.