java制作简易计算器

public class Demo08 {
    public static void main(String[] args) {
        /*制作一个简易的计算器
       思路:定义加减乘除
       添加循环
       完善程序
         */
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请输入一个数字");
            double i = scanner.nextDouble();
            System.out.println("在输入一个数字");
            double j = scanner.nextDouble();
            System.out.println("请选择将进行的操作（+ - * /）");
            String operator = scanner.next();
            switch (operator) {
                case "+":
                    double sum1 = add(i, j);
                    System.out.println("=" + sum1);
                    break;
            }
            switch (operator) {
                case "-":
                    double sum2 = substraction(i, j);
                    System.out.println("=" + sum2);
                    break;
            }
            switch (operator) {
                case "*":
                    double sum3 = multiplication(i, j);
                    System.out.println("=" + sum3);
                    break;
            }
            switch (operator) {
                case "/":
                    if (j == 0) {
                        System.out.println("被除数不能为0");
                    } else {
                        double sum4 = division(i, j);
                        System.out.println("=" + sum4);
                        break;
                    }
            }
            System.out.println("输入continue继续，输入end结束！");
            String str = scanner.next();
            if (str.equals("end")) {
                System.out.println("计算结束");
                break;
            } else if (str.equals("continue")) {
                System.out.println("计算继续");
            } else {
                System.out.println("指令错误");
                break;
            }


        }


        scanner.close();

    }


    public static double add(double i, double j) {
        return i + j;
    }

    public static double substraction(double i, double j) {
        return i - j;
    }

    public static double multiplication(double i, double j) {
        return i * j;
    }

    public static double division(double i, double j) {
        return i / j;

    }
}