的NullReferenceException是unhandles使用Windows窗體C＃

-3

我得到異常的NullReferenceException是unhandles使用Windows窗體C＃

NullReferenceException was unhandled

我已經嘗試了一次又一次之後，解決這一點，但小時，我來這裏尋求幫助。

這是我收到的錯誤：

Form1 objectForm1 = new Form1(); 
for (int i = 0; i < 1; i++) 
{ 
    objectForm1.taskBox.Items.Add(
     objectForm1.taskItems[i].TaskName + 
     objectForm1.taskItems[i].TaskDescription + 
     objectForm1.taskItems[i].TaskPriority + 
     objectForm1.taskItems[i].TaskDueDate + 
     objectForm1.taskItems[i].TaskCompletion); 
}

我知道這是不是很多與上述工作，但這裏是代碼的另一部分，我想創建對象的引用來使用列表等，這些物品是指在ListBox顯示：

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 
using System.Windows.Forms; 

namespace Programming_and_Data_Structures_ToDoList 
{ 
    public partial class Form1 : Form 
    { 
     public ObjectFile[] taskItems = new ObjectFile[10]; 
     public Form1() 
     { 
      InitializeComponent(); 
     } 

     public void FormMain() 
     { 
      //creating the form links----| 
      Form2 objectForm2 = new Form2(); 
      Form1 objectForm1 = new Form1(); 
      //---------------------------| 

      //ABOVE IS CREATING THE OBJECT REFERENCE 
      //BELOW IS SETTING THE VALUES 
      string taskName = objectForm2.TaskNameBox.Text; 
      string taskDescription = objectForm2.TaskDescBox.Text; 
      decimal taskPriority = objectForm2.PriorityUpDown.Value; 
      string taskDueDate = objectForm2.DateTimePicker.Value.ToShortDateString(); 
      string taskCompletion = objectForm2.completion; 

      for (int i = 0; i < 1; i++) 
      { 
       taskItems[i] = new ObjectFile(Convert.ToString(taskName), Convert.ToString(taskDescription), Convert.ToInt32(taskPriority), Convert.ToString(taskDueDate), taskCompletion); 
      } 
     } 

     private void newToolStripMenuItem_Click(object sender, EventArgs e) 
     { 
      Form2 Form2Object = new Form2(); //creates the object link form2 

      Form2Object.ShowDialog(); //Shows Form2 (Task input menu) 
     } 

     private void editToolStripMenuItem_Click(object sender, EventArgs e) 
     { 
      Environment.Exit(0); //exits the whole application 
     } 

     public void optionsToolStripMenuItem_Click(object sender, EventArgs e) 
     { 
     } 
    } 
    //OBJECT CLASS 
    public class ObjectFile 
    { 
     public string TaskName { get; set; } 
     public string TaskDescription { get; set; } 
     public decimal TaskPriority { get; set; } 
     public string TaskDueDate { get; set; } 
     public string TaskCompletion { get; set; } 

     public ObjectFile(string taskName, string taskDescription, decimal taskPriority, string taskDueDate, string taskCompletion) 

     { 
      TaskName = taskName; 
      TaskDescription = taskDescription; 
      TaskPriority = taskPriority; 
      TaskDueDate = taskDueDate; 
      TaskCompletion = taskCompletion; 
     } 
    } 
}

來源

2015-04-25 user4774392

？ –

什麼是「taskBox」?,此外，for循環有點冗餘..如果您已經使用字符串類型對象，則「Convert.ToString」也是多餘的。 – User2012384

您設置您的taskItems在FormMain，但在代碼中這個方法失敗沒有呼叫。

可能修復 - 你爲什麼要使用For循環..用一個單一的，硬編碼的迭代調用該方法

Form1 objectForm1 = new Form1(); 
objectForm1.FormMain(); 
for (int i = 0; i < 1; i++) ....

對於標準的措施，調查NRE退房What is a NullReferenceException, and how do I fix it?

來源

2015-04-25 01:58:49

的NullReferenceException是unhandles使用Windows窗體C＃

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