runnable

[yasir badshah]

what is runnable class & what it's work tell me.

[Michael Morris]

Hi Yasir,
Runnable isn't a class, its an interface with just one method:

public void run();

The class Thread implements Runnable, but its run method doesn't do anything so you have to overload it if you extend Thread and want to do some work in a separate thread. Most of the time programmers choose to implement the Runnable interface since that allows them to extend a different more appropriate class for the type of work they are doing. This works fine because the Thread class has a constructor which takes a Runnable as a parameter. After the Thread object is constructed then all you have to do is call its start() method and your Runnable is off and running (sorry for the pun) like this:

Thread runner = new Thread(myRunnableClassInstance):
runner.start();

Hope this helps
Michael Morris
SCJP

[Michael Morris]

I meant that you have to override the run() method, not overload it.
Sorry about that
Michael Morris
SCJP