用java写一个简单的计算器

好的，下面是一个简单的 Java 计算器示例代码：

import java.util.Scanner;

public class Calculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        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();
        System.out.print("请选择运算符（+、-、*、/）：");
        String operator = scanner.next();
        double result = 0.0;
        switch (operator) {
            case "+":
                result = num1 + num2;
                break;
            case "-":
                result = num1 - num2;
                break;
            case "*":
                result = num1 * num2;
                break;
            case "/":
                if (num2 == 0) {
                    System.out.println("除数不能为零！");
                    return;
                }
                result = num1 / num2;
                break;
            default:
                System.out.println("输入的运算符不正确！");
                return;
        }
        System.out.println(num1 + " " + operator + " " + num2 + " = " + result);
    }
}

运行程序后，按照提示输入两个数字和运算符，程序将输出计算结果。