I am really new to programming so take it easy on  me :)

Here is the code.  Basically what I want it to do is whenever the user
enters in 1 2 or 3 to say good job.  When the user enters 4 to quit
and anything else display an error message.  This code works fine as
long as the user enters in a int if anything else is entered it
crashes.  How can i fix this?  Thanks

  import javax.swing.*;
   public  class Input123
  {
      public static void main(String[] args)
     {
        String input;
        int selection = 0;
        while (selection != 4) {
           input = JOptionPane.showInputDialog(null,"Enter in either
1, 2, 3, or 4 to quit");
           selection = Integer.parseInt(input);
           if(selection == 1 || selection == 2 || selection == 3) {
              JOptionPane.showMessageDialog(null,"Good Job");
           }
           else if(selection == 4){
              System.exit(0);
           }
           else  {
              JOptionPane.showMessageDialog(null,"You have entered an
invalid character, Please try again.");
           }

        }

        System.exit(0);
     }
  }