列表框和數據源 - 防止選擇第一項

Question

嘿。我有以下代碼填充我的列表框中

UsersListBox.DataSource = GrpList; 

然而，填充盒後，在列表中的第一項被默認選中與「選擇指數改變」事件觸發。如何防止在列表框填充後立即選擇項目，或者如何防止事件發生？

感謝

Answer 1

從點火保留的情況下，這裏是我在過去使用的兩個選項：

1. 註銷事件處理程序在設置數據源。

   UsersListBox.SelectedIndexChanged -= UsersListBox_SelectedIndexChanged; 
   UsersListBox.DataSource = GrpList; 
   UsersListBox.SelectedIndex = -1; // This optional line keeps the first item from being selected. 
   UsersListBox.SelectedIndexChanged += UsersListBox_SelectedIndexChanged; 
   

2. 創建一個布爾型標誌來忽略該事件。

   private bool ignoreSelectedIndexChanged; 
   private void UsersListBox_SelectedIndexChanged(object sender, EventArgs e) 
   { 
       if (ignoreSelectedIndexChanged) return; 
       ... 
   } 
   ... 
   ignoreSelectedIndexChanged = true; 
   UsersListBox.DataSource = GrpList; 
   UsersListBox.SelectedIndex = -1; // This optional line keeps the first item from being selected. 
   ignoreSelectedIndexChanged = false; 
   

Answer 2

也許DataSourceChanged你可以檢查的SelectedIndex的狀態，如果你的幸運，你可以再正義的力量的SelectedIndex = -1。

Answer 3

如果你只是想清除選定的值，你可以用你ClearSelected設置DataSource後。但是如果你不想讓事件發生，那麼你將不得不使用約瑟夫的方法之一。

Answer 4

好吧，它看起來像ListBox.DataSource設置後自動選擇第一個元素。其他解決方案很好，但它們不能解決問題。這是我怎麼解決這個問題：

// Get the current selection mode 
SelectionMode selectionMode = yourListBox.SelectionMode; 

// Set the selection mode to none 
yourListBox.SelectionMode = SelectionMode.None; 

// Set a new DataSource 
yourListBox.DataSource = yourList; 

// Set back the original selection mode 
yourListBox.SelectionMode = selectionMode; 

Answer 5

我使用下面，似乎爲我工作：

List<myClass> selectedItemsList = dataFromSomewhere 

//Check if the selectedItemsList and listBox both contain items 
if ((selectedItemsList.Count > 0) && (listBox.Items.Count > 0)) 
{ 
    //If selectedItemsList does not contain the selected item at 
    //index 0 of the listBox then deselect it 
    if (!selectedItemsList.Contains(listBox.Items[0] as myClass)) 
    { 
     //Detach the event so it is not called again when changing the selection 
     //otherwise you will get a Stack Overflow Exception 
     listBox.SelectedIndexChanged -= listBox_SelectedIndexChanged; 
     listBox.SetSelected(0, false); 
     listBox.SelectedIndexChanged += listBox_SelectedIndexChanged; 
    } 
} 

Answer 6

設置IsSynchronizedWithCurrentItem="False"，也SelectedIndex=-1和每一件事應該爲你