Threads

[putti don]

Hi,

class Th extends Thread
{
public void run(){System.out.println("ABC");}
public static void main(String a[])
{
Th th=new Th();
Thread t=new Thread(th);
t.start();//1
t.run();//2
}
}
output is ABC
ABC
I understood that at line 1 the run() method of the Runnable object th is called. But why is the output of line 2 ABC...should that be calling the run() method(which will not print anything) of Thread class?

Thanks.

[Henry Wong]

The default run() method of the thread class calls the run() method of the runnable object. And BTW, if you wait until the thread finishes and cleans up after itself, calling the run() method may actually not print anything as the runnable object may get reset.

One more point, you don't know that the first ABC is caused by the start() method. It may actually be the second.

Henry

[srikanth reddy]

Henry i didnt get you... could you explain once again ........

thanks
sri
[ October 12, 2005: Message edited by: srikanth reddy ]

[Abhijit Sontakey]

Hi srikant,
The run() method of the thread is being called in the method after start() method. However for the run() method to get executed standalone, the thread object must not reset or dead. If the thread object is dead, then run() method won't get executed and hence the output. You can try this by putting a join() before run() method in the code.

[Sunil Kumar Gupta]

Call to a run() method directly works same as
calling an ordinary method of a class.

calling run() does not create a thread.

Thread is always created using start() method.

The start method creates the system resources necessary to run the thread, schedules the thread to run, and calls the thread's run method.