Writing a program with 2 threads which prints alternatively

Question

I got asked this question recently in an interview.

Write a program with two threads (A and B), where A prints 1 , B prints 2 and so on until 50 is r

Answer 1

//simply use wait and notify and and set a counter and it will do  

public class ThreadalternatePrint implements Runnable {
    static int counter =0; 
    @Override
    public synchronized void run() {
        try {
            Thread.sleep(10);
        } catch (InterruptedException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        while(counter<51)
        {   ++counter;
        notify();
        System.out.println(Thread.currentThread().getName());
            try {
                    wait();
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
        }       
    }

    public static void main(String[] args) {
        ThreadalternatePrint obj1 = new ThreadalternatePrint();
        Thread Th1 = new Thread(obj1);
        Thread Th2 = new Thread(obj1);
        Th1.setName("Thread1");
        Th2.setName("Thread2");
        Th1.start();
        Th2.start();
    }


}