Does the main thread get control immediately after calling some thread's start() method?

Question

For example :

public class Example1 {

    public static void main(String[] args) {
        Loop loop = new Loop();
        loop.start(); //printing "Before start"
        System.out.println("After start");
    }
}

Can be a situation that the loop's run method finishes before the execution of the last line that prints "After Start"?

Answer 1

Once you start multi-threading, you would be wise to drop all assumptions you have about the order in which threads will run.

If it's important, you can use synchronizing operations but, without them, all bets are off.

Answer 2

Yes, you have no control over how the threads are executed/scheduled by the JVM.

If you want to introduce some kind of ordering (execute the two threads in sequence) the most straightforward way to do it would be to use one of the Lock objects that Java provides.