sleep()

[ashok khetan]

hi! When i run the following code, the output is:
entered in run
entered in run
end of run
end of run
As the run() method is synchronized and the sleep() method doesn't release the lock so the second thread shouldn't get a chance to enter in run(). But her as the output shows on calling the sleep() the second thread enters in the run method and executes //1. Why is it so? Can u help me pl?
thanks.
ashok.
______
class TestThread extends Thread {
public synchronized void run() {
System.out.println("entered in run"); //1
try {
sleep(1000);
} catch(InterruptedException ie) {}
System.out.println("end of run"); //2
}
public static void main(String args[]) {
new TestThread().start();
new TestThread().start();
}
}
________

[Valentin Crettaz]

Because you create 2 different Thread instances. So declaring run as synchronized won't give you the expected behaviour,since each of the Thread object will be able to get the lock on themselves without having to care about the other thread. What you could do is a class lock on the Thread class, and it should work, let me know !
HIH
Valentin

[Thomas Paul]

That's correct. The run() method is synchronized on the object.

[galen wang]

that's right. you created 2 instance of TestThread, each has a instance method run() belong to different object.
if you change the code to
class TestThread extends Thread {
public void run() {
run_test();
}
public static synchronized void run_test() {
System.out.println("entered in run"); //1
try {
sleep(1000);
} catch(InterruptedException ie) {}
System.out.println("end of run"); //2
}
public static void main(String args[]) {
new TestThread().start();
new TestThread().start();
}
}
then the resule will be
entered in run
end of run
entered in run
end of run
this is because the method run_test() only have one entity, its belong to the class.

[ashok khetan]

Thanks a lot galen,valentin,Thomas!!
I got the point!!
ashok.