用JAVA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 scanner = new Scanner(System.in);
        double num1, num2, result = 0;
        char operator;

        System.out.print("Enter first number: ");
        num1 = scanner.nextDouble();
        System.out.print("Enter second number: ");
        num2 = scanner.nextDouble();
        System.out.print("Enter operator (+, -, *, /): ");
        operator = scanner.next().charAt(0);

        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");
                break;
        }

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

这个程序首先要求用户输入两个数字和操作符，然后使用switch语句计算结果并输出。注意，这个程序没有进行任何错误检查，例如用户输入无效的操作符或尝试除以0。