이거 에러 왜 생기나요?? 자바

[ㄴㅁㅇㄹㄴㅇㅁ..(211.217)]

package study;

class ParentA{
 
 public void display() throws NullPointerException{
  
 }
}

class ChildA extends ParentA{

 public void display() throws Exception{
  
 
}
public class Ex02_Exception08 {
 public static void main(String[] args){
  ParentA pa = new ChildA();
  
  try {

   
   pa.display();
   

   
  
  } catch (NullPointerException ne) {
 
   e.printStackTrace();
  }
  
  
  
 }

}