Java Array Indexing

Question

    class anEvent{ 
  String number;
  String dueTime;
 }



public static void main(String args[]) {
      int x = args.length / 2;
      int y = args.length;
      anEvent [] order = new anEvent [x];
      for(int i=0; i<x; i++){
       if(i==0){
        order[i].number = args[0]; //Line(#)
        order[i].dueTime = args[1];
       } else if ( i % 2 == 0){
       order[i].number = args[i];
       order[i].dueTime = args[i];
       } else if ( i % 2 != 0){
        order[i].number = args[i+1];
        order[i].dueTime = args[i+1];
       } else if ( i == x -1){
        order[i].number = args[x-1];
        order[i].dueTime = args[x-1];
       }

      }

Java complains that a Null Pointer exceptuion is present at line # in the above snippet.

What's the matter?

ps: I know that the snippet can be cleaned up but there should be no problem at all on line #

Answer 1

When an array is created, all the array elements are null. In your case, you need to fill the array with new anEvent() instances.

Answer 2

Make the first line of your for-loop:

order[i] = new anEvent();

As is, you are not initializing anything in the array (they're all null), so when you try to access the fields you get that exception.