java做个简易计算器

在Java中，创建一个简易计算器可以通过控制台输入和基本的算术运算实现。以下是一个简单的步骤和代码示例：

1. 首先，定义一个Calculator类，包含两个方法：`add`用于加法，`subtract`用于减法，`multiply`用于乘法，`divide`用于除法。

public class Calculator {
    public double add(double num1, double num2) {
        return num1 + num2;
    }

    public double subtract(double num1, double num2) {
        return num1 - num2;
    }

    public double multiply(double num1, double num2) {
        return num1 * num2;
    }

    public double divide(double num1, double num2) throws ArithmeticException {
        if (num2 != 0) {
            return num1 / num2;
        } else {
            throw new ArithmeticException("Division by zero is not allowed.");
        }
    }
}

2. 接着，创建一个`main`方法来获取用户的输入，并调用Calculator类的方法进行计算。

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Calculator calculator = new Calculator();

        System.out.println("Enter first number: ");
        double num1 = scanner.nextDouble();
        System.out.println("Enter second number: ");
        double num2 = scanner.nextDouble();
        System.out.println("Enter an operator (+, -, *, /): ");
        String operator = scanner.next();

        double result;
        switch (operator) {
            case "+":
                result = calculator.add(num1, num2);
                break;
            case "-":
                result = calculator.subtract(num1, num2);
                break;
            case "*":
                result = calculator.multiply(num1, num2);
                break;
            case "/":
                result = calculator.divide(num1, num2);
                break;
            default:
                System.out.println("Invalid operator. Please try again.");
                return;
        }

        System.out.printf("Result: %.2f\n", result);
        scanner.close();
    }
}