public class Main {
   public static void main(String[] args) {
     final Object o1 = new Object();
     final Object o2 = new Object();
   
     new Thread() {
       public void run() {
          synchronized(o1) {
            synchronized(o2) {
            }
          }
       }
     }.start();
   
     new Thread() {
       public void run() {
          synchronized(o2) {
            synchronized(o1) {
            }
          }
       }
     }.start();
   }
}