java import java.util.Scanner;

public class Calculator { public static void main { Scanner scanner = new Scanner; System.out.println; double num1 = scanner.nextDouble; System.out.println; double num2 = scanner.nextDouble; System.out.println; String operator = scanner.next; double result = 0; // 初始化后来啊为0

    switch  {
        case "+":
            result = num1 + num2;
            break;
        case "-":
            result = num1 - num2;
            break;
        case "*":
            result = num1 * num2;
            break;
        case "/":
            if  {
                System.out.println;
                return; // Ru果除数为0，则输出错误信息并收尾程序
            } else {
                result = num1 / num2;
            }
            break;
        default:
            System.out.println;
            return; // Ru果输入的运算符不是+、-、*、/中的一个，则输出错误信息并收尾程序
    }
    System.out.println;
}

}