calculator/Calculator.java

import java.util.Scanner;

public class Calculator {

    // 加法
    public double add(double a, double b) {
        return a + b;
    }

    // 减法
    public double subtract(double a, double b) {
        return a - b;
    }

    // 乘法
    public double multiply(double a, double b) {
        return a * b;
    }

    // 除法
    public double divide(double a, double b) {
        if (b == 0) {
            throw new IllegalArgumentException("Denominator cannot be zero.");
        }
        return a / b;
    }

    // 取余
    public double remainder(double a, double b) {
        return a % b;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Calculator calc = 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("Choose operation (+, -, *, /, %):");
        char operation = scanner.next().charAt(0);

        double result;
        switch (operation) {
            case '+':
                result = calc.add(num1, num2);
                break;
            case '-':
                result = calc.subtract(num1, num2);
                break;
            case '*':
                result = calc.multiply(num1, num2);
                break;
            case '/':
                result = calc.divide(num1, num2);
                break;
            case '%':
                result = calc.remainder(num1, num2);
                break;
            default:
                System.out.println("Invalid operation");
                scanner.close();
                return;
        }

        System.out.println("Result: " + result);
        scanner.close();
    }
}