IndexOutOfBoundsException when adding to ArrayList at index

Question

I get exception Exception in thread \"main\" java.lang.IndexOutOfBoundsException: Index: 1, Size: 0 for the below code. But couldn\'t understand why.

Answer 1

If you REALLY want "Elephant" at index 1, then you can add another (e.g. null) entry at index 0.

public class App {
public static void main(String[] args) {
    ArrayList s = new ArrayList<>();

    s.add(null);
    s.add("Elephant");

    System.out.println(s.size());                
  }
}

Or change the calls to .add to specify null at index 0 and elephant at index 1.