在窗體上顯示類內容

我有一個工作列表由一個類填充（或者我假設），並試圖在窗體上的一組文本框中顯示唯一的記錄。在窗體上顯示類內容

public partial class frm_people : Form 
{ 

    public frm_people() 
    { 
     // Loads the Form 
     InitializeComponent(); 

     LoadData(); 

     ShowData(); 

    } 

    // Global Variables 

    private People peopleClass; 
    private ArrayList peopleArrayList; 

    private int numberOfPeople; 
    private int currentPeopleShown; 

    private void ShowData() 
    { 
     // Add to Text Box based on current Record 
     txt_peopleName.Text = ((People)peopleArrayList[currentPeopleshown]).name;** 
    } 

    private void LoadData() 
    { 

     List<People> peopleList = new List<People>(); 

     People data = new People("James Bond", false, "Cardiff"); 

     peopleList.Add(data); 

     numberOfPeople = 1; 
     currentPeopleShown = 0; 
    } 
}

我得到一個錯誤（由**注）：「未設置爲一個對象的實例對象引用」

我知道類是通過引用工作，如何嘗試這種顯示記錄的方式？最終目標是通過使用currentPeopleShown變量，可以自由滾動多個記錄。

來源

2013-04-09 user2261755

我沒有看到peopleArrayList被設定。如果它從未設置，那麼值爲空，這就是爲什麼你會得到這個錯誤。 – atbebtg 2013-04-09 16:38:26

或者你可以消除的ArrayList一起，只是這樣做

public partial class frm_people : Form 
{ 
    List<People> peopleList; 
    public frm_people() 
    { 
     // Loads the Form 
     InitializeComponent(); 

     peopleList = new List<People>(); 
     LoadData(); 

     ShowData(); 

    } 

    // Global Variables 

    private People peopleClass; 

    private int numberOfPeople; 
    private int currentPeopleShown; 

    private void ShowData() 
    { 
     // Add to Text Box based on current Record 
     txt_peopleName.Text = (peopleList[0]).name;** 
    } 

    private void LoadData() 
    { 

     People data = new People("James Bond", false, "Cardiff"); 

     peopleList.Add(data); 

     numberOfPeople = 1; 
     currentPeopleShown = 0; 
    } 
}

來源

2013-04-09 16:42:21

我試過這個，但錯誤狀態「peopleList在當前上下文中不存在」當我將LoadData方法移動到ShowData之一時，整個事情就起作用了。我想我可能對課堂本身有問題，我會研究它。謝謝！ – user2261755 2013-04-09 20:04:48

試試這個：

private void ShowData() 
    { 
     // Add to Text Box based on current Record 
     if(peopleArrayList[currentPeopleshown]!=null) 
     txt_peopleName.Text = ((People)peopleArrayList[currentPeopleshown]).name; 
    }

來源

2013-04-09 16:35:05

相同的錯誤會在if行的結尾出現。 – user2261755 2013-04-09 16:37:13

你peopleList超出範圍。

List<People> peopleList = new List<People>(); 

private void LoadData() 
{ 
    //... 
}

數組沒有被使用，所以使用peopleList：

txt_peopleName.Text = peopleList[currentPeopleshown].name;

你不會需要numberOfPeople變量，你可以使用peopleList.Count

來源

2013-04-09 16:40:45 LarsTech

你在哪裏設置peopleArrayList ？

試試這些線路上：

private void LoadData() 
{ 
    peopleArrayList = new ArrayList(); 
    People data = new People("James Bond", false, "Cardiff"); 

    peopleArrayList.Add(data); 

    numberOfPeople = 1; 
    currentPeopleShown = 0; 
}

來源

2013-04-09 16:41:09

在窗體上顯示類內容

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