public class A {
  int i;
  int j;
  void funA()
  {
    i = i+1;
    System.out.println(i);
    j = j+1;
    System.out.println(j);
  }
}

......................................................................

public class Demo<G> {
  G x;
  public static void main(String[] args) {

  Demo<A> d3 = new Demo<A>();
  try
  {
    d3.x.i = 5;//why Null pointer Exception
  }
  catch (Exception e) {
    e.printStackTrace();
  }
 }
}