This is a program I recently wrote  and was wondering what the default protion would be? here is the program below,

package code_improvement;import java.util.Scanner;/**
 *
 * @author Brian
 */
public class Code_improvement {    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
         int n1, n2, opt, add, sub, mul;
        double div;
        Scanner Keyboard = new Scanner(System.in);
        System.out.println("Hello this program acts as a calculator");
        System.out.print("Enter first number:");
        n1 = Keyboard.nextInt();
        System.out.print("Enter second number:");
        n2 = Keyboard.nextInt();
        while(true)
        {
            System.out.println("Enter 1 for addition");
            System.out.println("Enter 2 for subtraction");
            System.out.println("Enter 3 for multiplication");
            System.out.println("Enter 4 for division");
            System.out.println("Enter 5 to Exit");
            opt = Keyboard.nextInt();
            switch(opt)
            {
                case 1:
                add = n1 + n2;
                System.out.println("Total Calculation:"+add);
                break;                case 2:
                sub = n1 - n2;
                System.out.println("Total Calculation:"+sub);
                break;                case 3:
                mul = n1 * n2;
                System.out.println("Total Calculation:"+mul);
                break;                case 4:
                div = (double)n1 / n2;
                System.out.println("Total Calculation:"+div);
                break;                  case 5:
                System.exit(0);
                break;
            }