This is a class to calculate the average of numbers
import javax.swing.JOptionPane; public class Average { public static void main(String args[]) { int sum = 0, n = 0, score; double avg; String scoreString; scoreString = JOptionPane.showInputDialog("Please input a number:"); score = Integer.parseInt(scoreString); while (score != -1) { sum = sum + score; n = n + 1; scoreString = JOptionPane .showInputDialog("Please input a number: "); score = Integer.parseInt(scoreString); } if (n > 0) { avg = (double) sum / n; JOptionPane.showMessageDialog(null, n + "Numbers' Avage: " + avg, " ", JOptionPane.INFORMATION_MESSAGE); } else JOptionPane.showMessageDialog(null, "You didn't enter any number!" + "", "You didn't enter any number!", JOptionPane.INFORMATION_MESSAGE); System.exit(0); } }