简易计算器

//实现计算器
 public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        boolean flag=true;

        while(flag){
            System.out.println("请选择要进行的操作（+、-、*、/）,输入x代表终止运行：");
            String operator = scanner.next();

            System.out.print("请输入第一个数字：");
            double num1 = scanner.nextDouble();

            System.out.print("请输入第二个数字：");
            double num2 = scanner.nextDouble();

            switch (operator) {
                case "+":
                    System.out.printf("%.2f + %.2f = %.2f", num1, num2, num1 + num2);
                    System.out.println();
                    break;

                case "-":
                    System.out.printf("%.2f - %.2f = %.2f", num1, num2, num1 - num2);
                    System.out.println();
                    break;

                case "*":
                    System.out.printf("%.2f * %.2f = %.2f", num1, num2, num1 * num2);
                    System.out.println();
                    break;

                case "/":
                    if (num2 != 0) {
                        System.out.printf("%.2f / %.2f = %.2f", num1, num2, num1 / num2);
                        System.out.println();
                    } else {
                        System.out.println("除数不能为零！");
                    }
                    break;
                case "x":
                    flag=false;
                    System.out.println("结束运行！");
                    scanner.close();
                    break;
                default:
                    System.out.println("无效的运算符！");
                    break;
            }
        }

    }