This programs hangs after printing two lines. How can i correct it?

Question

public class ThreadTest {
     static class FirstThread implements Runnable {
          public synchronized void run() {
               try {
                    wait();
               } catch (InterruptedException e) { }
               System.out.println("First thread starts");
               System.out.println("First thread ends");
     static class SecondThread implements Runnable {
          public synchronized void run() {
               System.out.println("Second thread starts");
               System.out.println("Second thread ends");
               notifyAll();
     public static void main(String[] args){
          Thread t1 = new Thread(new FirstThread());
          Thread t2 = new Thread(new SecondThread());
          t1.start();
          t2.start();
          try {
               t1.join();
          } catch (InterruptedException e) { }
It is giving output as :
Second thread starts
Second thread ends

Answer 1

Your two synchronizations should be on a same object for the wait/notify pair to be working. The object should be the one on which both wait and notify are called.
Message was edited by:
hiwa