Multi-Threads in Java

Multi-Threads in Java

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Threads: A difficult task (sometimes to implement but (for sure) to debug) that cannot be implemented by all programming languages.

A thread is an autonomous process that runs in memory in order to perform a specific task. The threads usually created by a program.

While a tread is created, it performs its task in "parallel" with its creator (the program). Well, the word "parallel" basically depends on two main things:

1. The Operating System (multi tasking capabilities).
2. The processor (Multi threading technology, Dual Core, multi processor system etc). But, anyway, I will not go too far with the OS & hardware issues.

A program can create more than one thread: In such case we have a multithread situation.

Java is one of very few languages (for my opinion) that allow a relatively easy way of creating and processing threads. There are two basic methods to do this:

1.The easy but not always a productive way: Inherited from build-in class Tread.

2.The usual way: By executing a runnable interface. An interface is the Java method to handle multiple inheritance.

A very simple example that shows how to use threads is the following: Suppose that we have to count from 0 to… 11..!! yes… yes… don’t "lol" you lamer !!…. the example is for educational purposes. But, of course, you can extend it to handle more… complex situations.

Well,… instead of making a for loop to count from 0 to 11 we can apply the "divide and conquer" method: Creating 3 threads: Thread One will count from 0 - 3. Thread Two will count from 4 - 7. Thread Three will count from 8 - 11. Well again…. i am just thinking… if a brute force apps could be "broken down" in many such steps…. ;) ….

I provide the source code of the above example… by using both methods. I suggest you to use my code for practice. In addition, please extend my code to handle more…. "complex" situations… ;)

Note: See how the threads are asynchronously executed once they are started.

/*--------------------------------------------------------------------------------------------------*/
/*
*  (c) Thiseas 01/10/06
*  Multi threads in Java
*  1st way: extending the Thread class.
*/
public class myThreads
{

 
 public static void main(String [] args)
 {
   System.out.println(\"Begin main Function\");
   mThread Thread_One = new mThread (\"One\",0,3);
   mThread Thread_Two = new mThread (\"Two\",4,7);
   mThread Thread_Three = new mThread(\"Three\",8,11);
   
   Thread_One.start();
   Thread_Two.start();
   Thread_Three.start();
   
   System.out.println(\"End main Function\");
   
 }// main
}//myThreads


class mThread extends Thread
{
 private String ThreadName;
 private int StartFrom;
 private int FinishTo;
 
 public mThread(String name, int n1, int n2)
 {
   ThreadName = name;
   StartFrom = n1;
   FinishTo = n2;
 }

 public void run(){
   for (int i=StartFrom; i<=FinishTo; i++)
     System.out.println(ThreadName+ \"Counter:\" +i);
 }


}//mThread
/*--------------------------------------------------------------------------------------------------*/
</code> 

2nd way

[code]
/*--------------------------------------------------------------------------------------------------*/
/*
*  (c) Thiseas 01/10/06
*  Multi threads in Java
*  2nd way: Implements a Runnable Interface
*/
public class myThreads2
{

 
 public static void main(String [] args)
 {
   System.out.println(\"Begin main Function\");

   mThread Thread_One = new mThread (\"One\",0,3);
   mThread Thread_Two = new mThread (\"Two\",4,7);
   mThread Thread_Three = new mThread(\"Three\",8,11);
   
   
   System.out.println(\"End main Function\");
   
 }// main
}//myThreads2


class mThread implements Runnable
{
 private String ThreadName;
 private int StartFrom;
 private int FinishTo;
 

 public mThread(String name, int n1, int n2)
 {
   ThreadName = name;
   StartFrom = n1;
   FinishTo = n2;

   Thread t = new Thread(this);
   t.start();

 }

 public void run(){
   for (int i=StartFrom; i<=FinishTo; i++)
     System.out.println(ThreadName+ \"Counter:\" +i);
 }


}//mThread
/*--------------------------------------------------------------------------------------------------*/