Question

(Thread) A.join() – causes current thread to wait for the thread A to complete.
I supposed then that calling this.join() from the run method will cause thread to deadlock – that it will wait for itself to complete. However it doesn’t happen – code compiles and runs just fine – without deadlock. What happens when I call this.join() then?

Answer 1

The OP uses this.join() in the provided example

Nathan in his example uses Thread.currentThread().join() instead.

By using this.join() a new thread is created which is getting joined, but the main thread is intact.

@Nathan
The following works as intended:

public class Main extends Thread {

    @Override
    public synchronized void run() {
       super.run();
       try {
           this.join();
       } catch (InterruptedException e) {
           e.printStackTrace();
       }
    } 

    public static void main(String[] args) {
        new Main().start();
        System.out.println("hello");
    }
}