Question

Here is my code

public class ThreadLearn{
private static class Check implements Runnable{
    public void run(){

        System.out.printf("\nInCheck %s", Thread.currentThread().getName());
    }
}

public static void main(String[] args){

   Thread t;
   int i=0;
   while(i<2){
      t = new Thread(new GetData());
      t.start();
      System.out.printf("\n%s: ", t.getName());
      i++;
   }

}

}

The output is:

InRun Thread-0
Thread-0:
Thread-1:
InRun Thread-1

I have two questions:

1. Should not the output be

   InRun Thread-0

   Thread-0:

   InRun Thread-1

   Thread-1:

2. Once the t.start() is done, will it wait for the run() to be executed and then create the second thread? what if i want to do the following

   while(required)

   new Thread().start();

and in my run method i can have all the stuff that i want the threads to accomplish in parallel so that it doesnt wait for one thread to complete the run method and then create the second thread.

Thanks

Answer 1

Should not the output be …

No. Threads run independently of each other. The JVM and operating system decide when which thread is running. In general, the order in which two threads are executed is unpredictable. It could very well happen that when you run the program again, the result is different.

Once the t.start() is done, will it wait for the run() to be executed and then create the second thread?

No, it will not wait. The run() method of the new thread may start immediately, or later, depending on how threads are being scheduled.