as Ian said: The thread with the // doubt in the line is actually never started. It only invokes the run method without starting as a seperate thread. And since there is no seperate thread started with "T2" as name, you'll never read this.
Something else, "smily sharma" !
Please have a look into your private messages by clicking the "My Private Messages" link near the top of this page.
I'm not sure why the line wouldn't start a new thread, as was previously mentioned. Calling a Java thread's start method initializes a thread and calls its run() method. If the line were to read , the output would be T1T1T3. As was written in the original post, the code should print T1T2T3.