public class Main extends Thread {

  public static int amount = 0;

​

  public static void main(String[] args) {

    Main thread = new Main();

    thread.start();

    // Wait for the thread to finish

    while(thread.isAlive()) {

      System.out.println("Waiting...");

    }

    // Update amount and print its value

    System.out.println("Main: " + amount);

    amount++;

    System.out.println("Main: " + amount);

  }

  public void run() {

    amount++;

  }

}

​