C# - 从其他类中的其他类访问方法？

Question

我最近开始学习C#,所以我绝不是专家.无论如何,我试图创建一个面向对象的计算器,但我遇到了一个问题,似乎我无法从某些类中的其他类访问方法.我没有得到错误代码但是当我放下断点并调试应用程序时,变量的值为0.

如果我从DisplayUserData中删除该方法并将代码粘贴到我的主程序文件中,它运行正常.看起来DisplayUserData类似乎无法传递变量或从其他类中检索变量,为什么会这样呢？

哦,原谅可怕的方法,类和变量名称.

这是我的主程序文件:

namespace Calculator
{
    class Program
    {
        static void Main(string[] args)
        {
            GetUserInput userInput = new GetUserInput();
            Calculator calculator = new Calculator();
            DisplayUserData displayUserCalculation = new DisplayUserData();


            userInput.MethodOfCalculation();
            userInput.UserNumberInput();
            displayUserCalculation.DisplayCalculatedUserData();

        }
    }
}

接下来是我的GetUserInput类:

namespace Calculator
{
    public class GetUserInput
    {
        public char Choice;
        public decimal ValueOne;
        public decimal ValueTwo;

        public void MethodOfCalculation()
        {
            Console.WriteLine("Welcome to Calculator v.1!");
            Console.WriteLine("Please choose a method of calculation below.");
            Console.WriteLine("1: Addition");
            Console.WriteLine("2: Subtraction");
            Console.Write("Your choice: ");
            Choice = Console.ReadKey().KeyChar;
        }

        public void UserNumberInput()
        {
            Console.Clear();
            Console.WriteLine("Please enter two numbers for calculation!");
            Console.Write("Number One: ");
            ValueOne = Convert.ToDecimal(Console.ReadLine());
            Console.Write("Number Two: ");
            ValueTwo = Convert.ToDecimal(Console.ReadLine());
        }

    }
}

而Calculator类:

namespace Calculator
{
    public class Calculator
    {
        public decimal CalculateUserInput(char userChoice, decimal valueOne, decimal valueTwo)
        {
            decimal calculatedValue = 0;

            switch (userChoice)
            {
                case '1':
                    calculatedValue = valueOne + valueTwo;
                    break;
                case '2':
                    calculatedValue = valueOne - valueTwo;
                    break;
            }

            return calculatedValue;
        }
    }
}

最后是DisplayUserData类:

namespace Calculator
{
    class DisplayUserData
    {
        GetUserInput _userInput = new GetUserInput();
        Calculator _calculator = new Calculator();

        public void DisplayCalculatedUserData()
        {
            decimal calculatedValue = _calculator.CalculateUserInput(_userInput.Choice, _userInput.ValueOne, _userInput.ValueTwo);

            switch (_userInput.Choice)
            {
                case '1':
                    Console.WriteLine("Addition: " + _userInput.ValueOne + " + " + _userInput.ValueTwo + " = " + calculatedValue);
                    break;
                case '2':
                    Console.WriteLine("Subtraction: " + _userInput.ValueOne + " - " + _userInput.ValueTwo + " = " + calculatedValue);
                    break;
            }
        }
    }
}

Answer 1

您正在创建类中的类UserInput和Calculator类的新版本(实例)DisplayUserData.由于您使用的是新实例,因此这些实例无法访问main方法中使用的实例中包含的数据.不是在类中创建新实例,而是通过构造函数传递现有实例以供类使用.

namespace Calculator
{
    class DisplayUserData
    {
        private readonly GetUserInput _userInput;
        private readonly Calculator _calculator;

        DisplayUserData(GetUserInput userInput, Calculator calculator)
        {
            _userInput = userInput;
            _calculator = calculator;
        }

        public void DisplayCalculatedUserData()
        {
            decimal calculatedValue = _calculator.CalculateUserInput(_userInput.Choice, _userInput.ValueOne, _userInput.ValueTwo);

            switch (_userInput.Choice)
            {
                case '1':
                    Console.WriteLine("Addition: " + _userInput.ValueOne + " + " + _userInput.ValueTwo + " = " + calculatedValue);
                    break;
                case '2':
                    Console.WriteLine("Subtraction: " + _userInput.ValueOne + " - " + _userInput.ValueTwo + " = " + calculatedValue);
                    break;
            }
        }
    }
}

然后称之为

displayUserCalculation.DisplayCalculatedUserData(userInput, calculator);