Runnable vs Thread

prashantSum's Avatar
Contributor
hi all,
I think this is a regular question in interviews, and may be every seems to know the answer, that is which one is better implementing Runnable Interface or extending Thread,..

and... I heard lot of people saying implementing Runnable interface is better...

but... I din't understood why implementing Runnable interface is better if so...
what I think is both are different ways of creating threads..

some explanation please......
shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
Its always better to implement a Runnable interface than to extend a Thread because

1 Using an interface it more flexible than subclassing.
2 Implementing an interface keeps OO option open and you can use inheritance.

Thanks
Shabbir Bhimani
prashantSum's Avatar
Contributor
hi shabbir,
I din't understood clearly.....

about 1. why it flexible using Interface .. is this because we can extend some other object?
about 2. what OO options are option, I think only option open (other options are still available by subclassing also) by using an Interface is mutliple inheritance.
shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
Quote:
Originally Posted by prashantSum
about 1. why it flexible using Interface .. is this because we can extend some other object?
Because In the Runnable version you just create one ThreadedClass object and then created a bunch of Thread objects based on this Runnable object. Where as In "extends Thread" version, you actually have to create a new ThreadedClass object per thread that you want to start.
Quote:
Originally Posted by prashantSum
about 2. what OO options are option, I think only option open (other options are still available by subclassing also) by using an Interface is mutliple inheritance.
Yes You have an option of inheriting the clas from other Class if you wish to as you have not blocked the single inheritance by sub classing it.
nicemothi's Avatar
Light Poster
Can any one expalin this with sample code..That could help for better understanding..

thanks for quicker respose..
MohanV's Avatar, Join Date: Apr 2012
Newbie Member
if the thread class you are creating is to be subclass of some other class, it can’t extend from the Thread class. This is because Java does not allow a class to inherit from more than one class. In such a case one can use Runnable interface to implement threads.