Threads

[Mubeen Shaik]

Hi All,

I am confused with the output of this code. This is from Dan's Mock Exam.Please explain this code and output.

  
 
class A5 implements Runnable {
 
  public void run() {System.out.print(Thread.currentThread().getName());}
}
 
class B5 implements Runnable {
 
  public void run() {
 
      new A5().run();
 
      new Thread(new A5(),"T2").run();      
 
      new Thread(new A5(),"T3").start();      
  }
 

}
 

class C5 {
  public static void main (String[] args) {
    new Thread(new B5(),"T1").start();
}}
 

Thanks in advance,
Mubeen.

[Tony Morris]

T1T1T3

Which bit don't you understand?

[Carol Enderlin]

What about the output confused you? What did you think it would be?

[Mubeen Shaik]

Hi All,

new Thread(new A5(),"T2").run();

I thought it will be "T1T2T3". I think my Threads concept is not clear.



Thanks,
Mubeen.

[Carol Enderlin]

It's the difference between calling the run() method and calling the start() method. It's a little tricky since you need to implement a run() method.

To start a thread running you have to call the start() method. Calling run() just executes in the same thread.

[Tony Morris]

The call to Thread.run() merely delegates to it's encapsulated Runnable.run(). No new thread is started - it all executes in the same thread.

Calling Thread.start() is a direction to the thread scheduler to start a new thread. The thread scheduler, at its own discretion, will execute by calling the Thread.run() method - this occurs in the new thread.