计算器原理

public class Demo02 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入第一个数据");
        double result = scanner.nextDouble();
        double num2;
        int numCount = 1;

        System.out.println("请输入运算符，结束输入 = ");
        String sign = scanner.next();
        while(!sign.equals("=")) {
            numCount++;
            System.out.println("请输入第" + numCount + "个数据");
            num2 = scanner.nextDouble();

            switch (sign) {
                case "+":
                    result = add(result, num2);
                    break;

                case "-":
                    result = minus(result, num2);
                    break;

                case "*":
                    result = multiply(result, num2);
                    break;

                case "/":
                    result = divide(result, num2);
                    break;
            }

            System.out.println("请输入运算符，结束输入 = ");
            sign = scanner.next();
        }
        scanner.close();
        System.out.println("结果为：" + result);
    }


    public static double add(double num1, double num2) {
        return num1 + num2;
    }

    public static double minus(double num1, double num2) {
        return num1 - num2;
    }

    public static double multiply(double num1, double num2) {
        return num1 * num2;
    }

    public static double divide(double num1, double num2) {
        return num1 / num2;
    }


}