class ThreadTest extends Thread{
    @Override
    public void run() {
        new ChildThread().start();
        for(int i = 1;i<10;i++){
            System.out.println("Parent: "+i);
        }
    }
}
class ChildThread extends Thread{
    @Override
    public void run() {
        for(int i = 1;i<10;i++){
            System.out.println("child: "+i);
        }
    }
}