notify,wait example

public class Hello extends Thread {
 
 public void run()
 {
  System.out.println("wait...");
  synchronized(this) {
   try {
    this.wait();
   } catch (Exception e) {
    System.out.println(e.getMessage());
   }
  }
  System.out.println("child");
 }
 
 public static void main(String args[]) throws Exception
 {
  Hello h = new Hello();
  h.start();
  
  System.out.println("main");
  Thread.sleep(3000);
  synchronized(h) {
   h.notify();
  }

  System.out.println("main over");
 }
}