使用Java编写一个简易计算器

以下是一个简单的Java计算器程序：

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("请输入第一个数字：");
        num1 = input.nextDouble();

        System.out.print("请输入运算符号（+、-、*、/）：");
        operator = input.next().charAt(0);

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

        switch (operator) {
            case '+':
                result = num1 + num2;
                System.out.println(num1 + " + " + num2 + " = " + result);
                break;
            case '-':
                result = num1 - num2;
                System.out.println(num1 + " - " + num2 + " = " + result);
                break;
            case '*':
                result = num1 * num2;
                System.out.println(num1 + " * " + num2 + " = " + result);
                break;
            case '/':
                if (num2 == 0) {
                    System.out.println("除数不能为零！");
                } else {
                    result = num1 / num2;
                    System.out.println(num1 + " / " + num2 + " = " + result);
                }
                break;
            default:
                System.out.println("运算符输入有误！");
        }
        input.close();
    }
}

使用该程序，用户可以输入两个数字和一个运算符，程序将根据运算符计算结果并输出。例如，输入“3 + 5”，程序将输出“3.0 + 5.0 = 8.0”。