Converting int to string, adding to string then pointing to an url

Question

So I'm getting a null pointer exception here's a snippet of my code (theres plus signs on both sides of the a in my code):
private Image[] tiles;
public Map() {
for(int a=0; a<9; a++){
ImageIcon aa = new ImageIcon(this.getClass().getResource("mapsquares"+a+".png"));
tiles[a] = aa.getImage();
I've also tried:
private Image[] tiles;
public Map() {
for(int a=0; a<9; a++){
ImageIcon aa = new ImageIcon(this.getClass().getResource("mapsquares$s.png", String.valueOf(a)));
tiles[a] = aa.getImage();
whats wrong with either of these?
Edited by: Wub on Feb 28, 2013 3:17 PM

Answer 1

1.) You should use code tags when posting code.
2.) You should read the stacktrace closely to find out which exact line number in your code threw the exception.
My guess is that it's the line tiles[a] = aa.getImage(); because you didn't initialize the array tiles using the new operator. This is just a guess since you didn't post the full stacktrace. Also, NullpointerExceptions are one of the easiest to debug. Just adding print out lines at strategic values can show you which variables are initialized and which ones are not.