public class Point {
     public Point(int x, int y) {
       this.x = x; this.y = y;
     }
     public double getDist() {
       return Math.sqrt(x*x + y*y);
     }
  }

1. Is the above class thread-safe? If so explain why; if not, rewrite it to make it thread-safe.
2. Write a program in Java that can deadlock.
3. Extra credi: Given a Set s, write a class SetLock patterned after DoubleLock, so that you could write:

     new SetLock(s).lockInvoke(r)
   

   The above line would hold a lock on every Object in s and only then run the supplied Runnable. Hint: see Hint.