Wednesday, January 14, 2015

Program's Multitasking

Being multitasking is a great feature of a programming language. There are two types of multitasking: process-based and thread-based.
The process-based multitasking which allows a computer to run several programs at the same time, is mostly a function of the operating system.
The thread-based multitasking is more involved with the language-level support. Because one process can have several threads of execution.
However, many languages have no bulit-in support for multi-threading. To achieve the target, the programer has to reply on OS functions to create, begin, synchronize and end threads. It could be a nightmare, and the code won't be portable also.
Java has a easy-to-use built-in multithreading model. We can regard a program as a collection of parallel tasks (threads) that interact with one another.
The java.lang.Thread class is for creating and controlling threads.

First of all, we need create a subclass of Thread that include a run method.
  • The code within the run method performs the thread's task.
  • Each instantiation of the subclass corresponds to a single thread.
Then the controlling program invokes the java.lang.Thread.start method to start the thread.

The thread is implicitly stopped when the run method terminates.
We can also use the sleep method in the Thread class to cease execution for a desired time (ms).

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