Question

我正在尝试在load事件中初始化我的数组的元素（这是类的数组），但它没有被调用，也无法看到我做错了什么。

这是我的代码：

namespace Coffee_Shop_Login
{
    public partial class frmLogin : Form
    {
        public frmLogin()
        {
            InitializeComponent();
        }

        //Global Variables
        static int Maximum_Number_Of_Logins = 1;
        LoginDetails[] Employees = new LoginDetails[Maximum_Number_Of_Logins];//creating array of objects of type LoginDetails


        //method initialises the array objects when form loads
        private void frmLogin_Load(object sender, EventArgs e)
        {
            for (int i = 0; i < Employees.Length; i++)
            {
                Employees[i] = new LoginDetails(); // set up single element to a new instance of the object
            }
        }//end of frmLogin_Load() 

        private void btnLogin_Click(object sender, EventArgs e)
        {
            string username = "Johnny";
            Employees[0].Set_Employee_Username(username);
            MessageBox.Show("Username is: " + Employees[0].Get_Employee_Username());
        }
    }
}

namespace Coffee_Shop_Login
{
    class LoginDetails
    {
        //Public Mutator Functions
        //========================

        public void Set_Employee_Username(string username)
        {
            Employee_Username = username;//sets Employee_Username with value passed in
        }//end of Set_Employee_Username()


        public void Set_Employee_Password(string password)
        {
            Employee_Password = password;//sets Employee_Password with value passed in
        }//end of Set_Employee_Password()        


        //Public Accessor Functions
        //=========================

        public string Get_Employee_Username()
        {
            return Employee_Username;//returns the value of Employee_Username
        }//end of Get_Employee_Username()


        public string Get_Employee_Password()
        {
            return Employee_Password;//returns the value of Employee_Password
        }//end of Get_Employee_Password()


        //Private Member Variables
        private string Employee_Username;
        private string Employee_Password;

    }
}

当我运行应用程序时，由于未调用load事件，我收到此错误消息：

未处理的类型＆＃39; System.NullReferenceException＆＃39;发生在Coffee Shop Login.exe

附加信息：未将对象引用设置为对象的实例。

我需要添加什么才能使Load事件调用我的方法？

Answer 1

尝试在表单构造函数中实例化数组，而不是在类中实例化，如下所示：

public frmLogin()
    {
        InitializeComponent();
        Employees = new LoginDetails[Maximum_Number_Of_Logins];
    }

加载事件似乎没有被调用

1 个答案: