After asking for the red number, it should ask for green number, than blue. Even if I put in an abstract character like '~,' in editing, I won't get the error message until after all three questions have popped up. Here, if I put anything in, the scenario will crash. There is no terminal, so I don't know the error. Some of my code: String r = JOptionPane.showInputDialog("Red number:"); for (int x = 0; x < r.length(); x++) { char i = r.charAt(x); if (Character.isAlphabetic(i)) { JOptionPane.showMessageDialog(null, "Must be numeric!"); return; } if (x >= 3) { JOptionPane.showMessageDialog(null, "Too long!"); return; } }

When I pressed enter and put in "32" in the red input, the scenario had a run time error (stopped), but I don't know what's the cause because it works just fine in editing.