private Node getNodeAt(int idx) throws Exception {
  if(this.size == 0){
    throw new Exception("LinkedList is empty");
  }
  if(idx < 0 || idx >= this.size){
    throw new Exception("Invalid Index");
  }
  
  Node temp = this.head;
  
  for(int i = 1; i <= idx; i++){
    temp = temp.next;
  }
  
  return temp;
}