How come invoking a (static) method on a null reference doesn't throw NullPointerException?

I wrote this program in Java

public class Why {

  public static void test() {
    System.out.println("Passed");
  }

  public static void main(String[] args) {
    Why NULL = null;
    NULL.test();
  }

}

I read that invoking a method on a null object causes NullPointerException, and yet the above program doesn't? Why is this? Am I not understanding something correctly?