Threads Synchronization

[Balaji Bang]

Hi
I am talking about Devaka's Practice Exam-1 Q:72.

I made simple change in this..

public class SynchEx implements Runnable{

     static String s="ABC";

     public void run(){
          synchronized(this){
               System.out.print(s);
          }
     }

     public static void main(String args[])throws Exception{
    	 SynchEx ss=new SynchEx();
          Thread td=new Thread(ss);
          synchronized(ss)
         {
        	  System.out.println(Thread.currentThread().getName());
               td.start();
               Thread.sleep(1000);
               System.out.println("hello"+s);
               s="XYZ";
               Thread.sleep(4000);
               System.out.println("hello"+s);
               
          }
     }

In main method if the synchronized block has lock on object SynchEx that is 'ss' then synchronization works. if it is td then it will go and run method before it completes main. So in run() 'this' is the ss not 'td' ..

I understood like this. Am I Right???

[Ruben Soto]

Yes, you are correct.

[Punit Singh]

Yes, it is due to Thread.run() method in thread class.

  public void run() {
	if (target != null) {
	    target.run();
	}
    }   

It means for you:

  public void run() {
	if (ss!= null) {
	    ss.run();
	}
    }