As a general rule, there are at least three threads executing in
any Java program. First there's the main thread in which
your program is running. This is the thread that includes the
main() method that started your application. In an
applet this will be the thread into which the applet viewer or web
browser was launched.
Next, there's a low priority thread that handles garbage collection and runs finalizers.
In programs that use the AWT, there's also a screen updater thread that checks to see if anything needs to be repainted about 100 times a second.
Finally there are any threads your program has explicitly
spawned. However you're program is always running in one thread or
another. You're never outside the thread system. You can determine
the currently executing thread with the static Thread.currentThread() method:
public static Thread currentThread()
For example, the following program prints the name of the primary thread of execution:
public class PrimaryThread {
public static void main(String[] args) {
System.out.println(Thread.currentThread());
}
}You use the currentThread() method to get a reference
to the current thread so you can manipulate it.