Thread doubt

[ram shah]

 public class MyThread implements Runnable {
          public void run() {
                System.out.println("inside no args run");
                for (int i=1;i<=10;i++) {
                        System.out.println("Run by " + Thread.currentThread().getName());
                }
                try {
                Thread.sleep(1000);
                }catch (InterruptedException e) {}
          }
 
        public static void main(String args[]) {
 
                MyThread r = new MyThread();
                Thread t1 = new Thread(r);
                t1.setName("one");
                Thread t2 = new Thread(r);
                t2.setName("two");
                Thread t3 = new Thread(r);
                t3.setName("three");
                System.out.println("Pr of t1 = "+ t1.getPriority() +","+ "Pr of t2 = "+  t2.getPriority() +","+ "Pr of t3 = "+ t3.getPriority());
                t1.setPriority(3);
                t2.setPriority(5);
                t3.setPriority(7);
                System.out.println("Pr of t1 = "+ t1.getPriority() +","+ "Pr of t2 = "+  t2.getPriority() +","+ "Pr of t3 = "+ t3.getPriority());
 
                t1.start();
                t2.start();
                t3.start();
 
                if(Thread.currentThread().getPriority() == Thread.NORM_PRIORITY){
                        System.out.println("Inside  if block");                        
                        t2.yield();
                        System.out.println("Final run by " + Thread.currentThread().getName());}
             } //End of main
}//End of class
                                
                                
   

The result I got is as follows:

Pr of t1 = 5,Pr of t2 = 5,Pr of t3 = 5
Pr of t1 = 3,Pr of t2 = 6,Pr of t3 = 7
inside no args run
Run by one
�.
Run by one
Inside if block
inside no args run
Run by three
�.
Run by three
inside no args run
Run by two
�.
Run by two
Final run by main


Though t3 has max priority, t1 is run first.
value for NORM_PRORITY is 5, but I haven't given any Thread a priority of 5. Then how can the if loop execute?

Can anybody pls explain

[ahmed yehia]

I haven't given any Thread a priority of 5. Then how can the if loop execute?
if(Thread.currentThread().getPriority() == Thread.NORM_PRIORITY){

You are checking on the currentThread which is the "main Thread" which has a default priority of NORM_PRIORITY

[ram shah]

Thank for your comments Ahmed...but, I have few more doubts

(1) how thread "one" is executing before thread "three" when priority of thread "three" is greatre than priority of thread "one".

(2) If I set the priorities as below,
t1.setPriority(9)
t2.setPriority(5)
t3.setPriority(5)
How can I modify the if statement so that if the priority of the thread is 5, it yields to the other thread with same priority.

[Henry Wong]

(1) how thread "one" is executing before thread "three" when priority of thread "three" is greatre than priority of thread "one".

Threads actually takes time to start. I can't tell without running your code, but I would say thread one is running because thread three hasn't started yet.

How can I modify the if statement so that if the priority of the thread is 5, it yields to the other thread with same priority.

The way you coded it, only the main thread makes the check. You have to code it so that the threads that you want to check and yield, actually does the check and yield.

Henry