Hi Friend,

Difference:

1)If you want to extend the Thread class then it will make your class unable to extend other classes as java is having single inheritance feature whereas If you implement runnable interface, you can gain better object-oriented design and consistency and also avoid the single inheritance problems.

2)Extending the thread will give you simple code structure in comparison to Runnable Interface.

3)Using Runnable Interface, you can run the class several times whereas Thread have the start() method that can be called only once.

Thanks

The main difference between extending a Thread class and implementing the Runnable interface is, Extending the Thread class:When your class is extending the Thread class then your class becomes a single thread which is inheriting all the properties and characteristics of the Thread class and it becomes heavy. Implementing the Runnable interface:When your class implements the Runnable interface then you only override the run() method,but you create one or more instance(s) of the Thread class in that instance you pass the instance of your Runnable interface implemented class and then you apply the start() method on the Thread instance.So this instance(s) creates a seperate Thread(s) and every individual Thread runs seperately but not as a single heavy Thread in your program.