從另一個類添加列表框項目C＃

Question

嗨，大家好我試圖從另一個類中添加值到MainForm上的列表框但是我收到錯誤NullReferenceException是未處理的。這裏是我的代碼：

public partial class MainForm : Form 
{  
    Seats currentSeat = new Seats(); 

    public MainForm() 
    { 
     InitializeComponent(); // VS' s code 

     //1. Prepare the form before it is shown to the user. 
     InitializeGUI(); 
    } 

    private void InitializeGUI() 
    {   
     currentSeat.Seat(); 
    } 

**class Seats** 
{ 

    private string customerName = "Me "; 

    MainForm mainForm; 

    public void Seat() 
    { 
     SetDefaultValues(); 
    } 

    private void SetDefaultValues(){ 

     for (int seat = 1; seat <= 60; seat++) 
     {    
      mainForm.listBoxReservations.Items.Add(string.Format("{0} {1} ", seat,costumerName)); // **HERE IS THE ERROR NullReferenceException was unhandled** 

     } 

    } 
} 

任何建議

Answer 1

您尚未創建MainForm類和拼錯客戶名稱：

私人無效SetDefaultValues（）{

for (int seat = 1; seat <= 60; seat++) 
    {    
     mainForm.listBoxReservations.Items.Add(string.Format("{0} {1} ", seat,costumerName)); // **HERE IS THE ERROR NullReferenceException was unhandled** 

    } 

你實例變量這樣說：

private string customerName = "Me "; 

但你的代碼指的是這樣的：

costumerName