사칙연산계산기(모듈화)

import java.util.Scanner;
 
public class MyTest {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        MyTest mt = new MyTest();
        int num;
        float f;
        char calculation_opt;
        String choice = null;
        do {
            num = mt.printQt_integer(sc);
            f = mt.printQt_float(sc);
            calculation_opt = mt.printQt_calculation(sc);
            mt.printSwitch(calculation_opt, num, f);
            choice = mt.choice_opt(sc);
        } while (choice.equals("y") || choice.equals("Y"));
    }// main
 
    public int printQt_integer(Scanner sc) {
        System.out.print("정수를 입력 : ");
        int num = sc.nextInt();
        return num;
    }
 
    public float printQt_float(Scanner sc) {
        System.out.print("실수를 입력 : ");
        float f = sc.nextFloat();
        return f;
    }
 
    public char printQt_calculation(Scanner sc) {// 연산 종류 메서드
        System.out.print("+,-,*,/ => 연산을 입력 :  ");
        char calculation_opt = sc.next().charAt(0);
        return calculation_opt;
    }
 
    public void printSwitch(char calculation_opt, int num, float f) {// 연산기능
 
        switch (calculation_opt) {
        case '+':
            System.out.println(num + f);
            break;
        case '-':
            System.out.println(num - f);
            break;
        case '*':
            System.out.println(num * f);
            break;
        case '/':
            System.out.println(num / f);
            break;
        default:
            System.out.println("연산을 잘못입력하셨습니다");
            break;
        }
    }
 
    public String choice_opt(Scanner sc) {// 반복여부확인 메서드
        System.out.print("추가로 계산하시겠습니까? y or n : ");
        String choice = sc.next();
        while (!(choice.equals("y") || choice.equals("Y") || choice.equals("n") || choice.equals("N"))) {
            System.out.print("다시 입력하시오 : ");
            choice = sc.next();
        }
        return choice;
    }
}