用Java写一个计算器程序

好的，我可以回答这个问题。以下是一个简单的Java计算器程序的代码：

import java.util.Scanner;

public class Calculator {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        double num1, num2, result;
        char operator;

        System.out.print("Enter first number: ");
        num1 = input.nextDouble();

        System.out.print("Enter operator (+, -, *, /): ");
        operator = input.next().charAt(0);

        System.out.print("Enter second number: ");
        num2 = input.nextDouble();

        switch(operator) {
            case '+':
                result = num1 + num2;
                break;
            case '-':
                result = num1 - num2;
                break;
            case '*':
                result = num1 * num2;
                break;
            case '/':
                result = num1 / num2;
                break;
            default:
                System.out.println("Invalid operator");
                return;
        }

        System.out.println(num1 + " " + operator + " " + num2 + " = " + result);
    }
}

这个程序可以让用户输入两个数字和一个运算符，然后计算并输出结果。