Question

我尝试在C＃中使用BindingList作为DataSource，但每当我尝试将第一个项添加到BindingList时，我都会抛出ArgumentOutOfRangeException。 在我的项目中，我需要清除BindingList并在将新项目设置为DataSource后添加新项目。

BindingList<string> dataSource = new BindingList<string>();
myComboBox.DataSource = dataSource;
dataSource.Add("something"); // Exception, here.

我知道异常是由.Net框架处理的，但我需要找到一种方法来避免它。

我也试过

List<DirectoryInfo> list = aList.ToList();
list.AddRange(bList);

//set the index to -1 as suggested
var index = myComboBox.SelectedIndex;
myComboBox.SelectedIndex = -1;

myComboBox.DataSource = null;
bindingList.Clear();
bindingList.AddRange(list.Distinct());
if (bindingList.Count > 0)
{
    //internal ArgumentOutOfRangeException here when binding
    myComboBox.DataSource = bindingList;
    myComboBox.SelectedIndex = index;
}
else
    myComboBox.DataSource = null;

谢谢，这是callstack

System.Windows.Forms.dll!System.Windows.Forms.ComboBox.SelectedIndex.set(int value)
System.Windows.Forms.dll!System.Windows.Forms.ListControl.DataManager_PositionChanged(object sender, System.EventArgs e)
System.Windows.Forms.dll!System.Windows.Forms.CurrencyManager.OnPositionChanged(System.EventArgs e)
System.Windows.Forms.dll!System.Windows.Forms.CurrencyManager.ChangeRecordState(int newPosition, bool validating, bool endCurrentEdit, bool firePositionChange, bool pullData)
System.Windows.Forms.dll!System.Windows.Forms.CurrencyManager.List_ListChanged(object sender, System.ComponentModel.ListChangedEventArgs e)
System.dll!System.ComponentModel.BindingList<System.__Canon>.OnListChanged(System.ComponentModel.ListChangedEventArgs e)
System.dll!System.ComponentModel.BindingList<System.__Canon>.FireListChanged(System.ComponentModel.ListChangedType type, int index)
System.dll!System.ComponentModel.BindingList<System.__Canon>.InsertItem(int index, System.__Canon item)
######.dll!System.Collections.ObjectModel.Collection<###########>.Add(######### item)

Answer 1

尝试这样的事情这是我刚刚在评论中说明的一个例子

var blist = new BindingList<string>();
blist.Add("something");
blist.Add("something2");
comboBox1.DataSource = blist;

如果您需要先将其分配为空，请执行此类操作

if(blist.Count > 0)
{
    comboBox1.DataSource = null;
    var blist = new BindingList<string>();
    blist.Add("something");
    blist.Add("something2");
    comboBox1.DataSource = blist;
}

对List<T>.Add方法或BindingList.Add方法进行一些研究另请参阅.Clear()方法和。Count()方法

使用BindingList的替代方法是BindingSource在此处找到关于此主题的更多阅读MSDN BindingSource Class

Answer 2

最后，我摆脱了我的问题！这是我找到的解决方案

首先，我将DataSource设置为null，因为我启动时BindingList始终为空。

comboBox1.DataSource = null;

然后，当我需要更新bindingList并添加一些项目时，我会做类似的事情

List<DirectoryInfo> list = aList.ToList();
list.AddRange(bList);

BeginUpdate();
bindingList.Clear();
bindingList.AddRange(list.Distinct());
EndUpdate();

这里是BeginUpdate和EndUpdate方法

private void BeginUpdate()
{
    //if the DataSource is going to be empty, adding the first item will
    //always trigger an ArgumentOutOfRangeException on the selected index.
    //to avoid this, we must stop the binding during the modification of the list.
    _Updating = true;
    comboBox1.DataSource = null;
}

private void EndUpdate()
{
    if (bindingList.Count > 0)
    {
        //the binding will set SelectedIndex to the old index when rebinding and it's possibily the wrong one.
        //the good index is always 0 but we set the index to -1 before to be sure to be able to trigger the
        //selectedIndex_changed method after _UpdatingRecentFolders is turn to false
        comboBox1.DataSource = bindingList;
        comboBox1.SelectedIndex = -1;
        _Updating = false;
        //I always want 0 but you can place the index you want
        comboBox1.SelectedIndex = 0;
    }
    else
    {
        comboBox1.DataSource = null;
        _Updating = false;
        comboBox1.SelectedIndex = -1;
    }
}

我还有一个selectedIndex_changed事件

private void comboBoxItem_SelectedIndexChanged(object sender, EventArgs e)
{
    if (!_Updating && comboBox1.SelectedIndex != -1 )
        aControl.SelectedItem = bindingList[comboBox1.SelectedIndex];
}

我希望这能帮助别人！

将第一个项添加到BindingList DataSource时的ArgumentOutOfRangeException

2 个答案: