Creating Threads

1. Extending "java.lang.Thread" Class
A typical procedure for using the Thread class for creating threads in execution is as follows: A class extending the Thread class overrides the run() method from the Thread class. The run() method consists of the code to be executed by the thread. Notice that while overriding run() method, it must have public access specifier. Do not call run() method directly using the object of the derived class. The start() method, which is inherited from the Thread class should be invoked using the object of derived class, to make the class eligible for running and causes to execute run() method. You can assign user specific name to a thread by using setName() method of Thread class.
Implementation:
The following program shows, how to use java.lang.Thread class to create multiple threads of a class.

class Process extends Thread
   {
    int start,end;
    Process(int s,int e,String name)
      {
       start=s; end=e;
       setName(name);
      }
    public void run()
      {
        for(int i=start;i<=end;i++)
         {
           System.out.println(“thread->”+getName()+” : “+i);
           try{
               Thread.sleep(100);
              }
           catch(InterruptedException ex){ex.printStackTrace();}	
         }
        System.out.println(Thread.currentThread()+ “ : thread Finished....”);	
      }
}
public class ExtendsThread 
 {
	public static void main(String[] args)
	{
		Process thrd1=new Process(1,5,”Real”);
		Process thrd2=new Process(6,10,”Java”);
		thrd1.start();
		thrd2.start();
	}
}

Output:
	thread->Java : 6
	thread->Real : 1
	thread->Real : 2
	thread->Java : 7
	thread->Real : 3
	thread->Java : 8
	thread->Java : 9
	thread->Real : 4
	thread->Java : 10
	thread->Real : 5
	Thread[Java,5,main] : thread Finished....
	Thread[Real,5,main] : thread Finished....

Implementing java.lang.Runnable Interface

The other and most commonly used method of creating threads is by ­implementing java.lang.Runnable interface. This method is preferred, when the class already inherits other class, thus you can not extend java.lang.Thread class more because multiple inheritance is not allowed in Java. But a class can implement multiple interfaces.
Runnable interface consists of one abstract method declaration:

public interface Runnable
    {
      void run();
    }

The following program implements Runnable interface for creating threads:
For Example:

class Job implements Runnable
  {	
    int start,end;
	Job(int s,int e)
	     { start=s; 
	        end=e;   }
	public void run()
	     {
	       for(int i=start;i<=end;i++)
		{
System.out.println(“thread:”+Thread.currentThread().getName()+”:“+i);
		try{   Thread.sleep(100);	 }
		catch(InterruptedException ex){ex.printStackTrace();}	
		}
 System.out.println(Thread.currentThread()+ “ : thread Finished....”);	
	 }
}
public class RunnableInterface 
  {  public static void main(String[] args) 
	{		
	Job obj1=new Job(1,3);
	Job obj2=new Job(6,8);
	Thread thrd1=new Thread(obj1);
	thrd1.setName(“Real”);
	Thread thrd2=new Thread(obj2);
	thrd2.setName(“Java”);
	thrd1.start();
	thrd2.start();
	}
 }

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