IGNOU BCA 4th sem Solved Assignment - What is multithreading? Explain the two ways of creating threads in Java programs. Also explain difference between notify() and notify All( ) methods.

What is multithreading? Explain the two ways of creating threads in Java programs. Also explain difference

between  notify() and notify All( ) methods. 

Ans

                Java provides built-in support for multithreaded programming. A multithreaded program contains two or more parts that can run concurrently. Each part of such a program is called a thread, and each thread defines a separate path of execution.

A multithreading is a specialized form of multitasking. Multithreading requires less overhead than multitasking processing.

I need to define another term related to threads: process: A process consists of the memory space allocated by the operating system that can contain one or more threads. A thread cannot exist on its own; it must be a part of a process. A process remains running until all of the non-daemon threads are done executing.

Multithreading enables you to write very efficient programs that make maximum use of the CPU, because idle time can be kept to a minimum

Creating a Thread:

Java defines two ways in which this can be accomplished:

• You can implement the Runnable interface.

• You can extend the Thread class, itself

notify(): this method should be called only when the current thread has already acquired the lock on the object. If the wait set of the object is non-empty then a thread from the set is arbitrarily chosen, removed and is re-enabled for thread scheduling. Of course, the thread will not be able to proceed unless the current thread releases the object’s lock.

notifyAll(): it’s same as the notify() method. The only difference is that in this case all the threads from the non-empty wait set of the object are removed and are re-enabled for thread scheduling in stead of only one thread from the wait set being picked arbitrarily, removed, and re-enabled for thread scheduling as is the case in notify() method.

'notify()' method wakes up a single thread waiting on the object

and passes the control of the monitor to it. So far so good and for

'notifyAll()' it says that its will wake up all the threads waiting on the object and will select a thread to pass control to it. Well as per