Multitasking:

Process based multitasking:

Thread based multitasking:

• Run a single program in multiple threads at a time
• A thread is the smallest unit of ....
• Example, one thread is writing content on a file at the same time another thread is performing spelling check.

Threading in java:

Thread is a program's path of execution in which processor execute code of program in different part at same  time.
Multi threading extends the idea of multitasking into applications where you can subdivide specific operations within a single application into individual threads. Each of the threads can run in parallel. The OS divides processing time not only among different applications, but also among each thread within an application.


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Runnable :
             > it is interface to implement by the class that need thread execution.
               >It remains the option to extend that class by other superclasses or you can say it is flexible way to use thread execution.
              >Must handle the exception or must enclosed the thread operations in try-catch block..
     
extend thread: it is class of thread to extend by the class that need thread execution.

	implements Runnable	extends Thread
Inheritance option	extends any java class	No
Reusability	Yes	No
Object Oriented Design	Good,allows composition	Bad
Loosely Coupled	Yes	No
Function Overhead	No	Yes