C# 为什么在UWP列表框中获得双击事件而不是单个事件?
我有一个包含一些元素的列表框。在my Page.XAML页面中,我有如下内容:C# 为什么在UWP列表框中获得双击事件而不是单个事件?,c#,uwp,C#,Uwp,我有一个包含一些元素的列表框。在my Page.XAML页面中,我有如下内容: <ListBox SelectionMode="Single" SelectionChanged="SelectedIndexChanged" x:Name="myList" HorizontalAlignment="Center" Margin="0,0,0,0" Width="350" Height="900" BorderThickness="0,0,0,0" RequestedTheme="Defaul
<ListBox SelectionMode="Single" SelectionChanged="SelectedIndexChanged" x:Name="myList" HorizontalAlignment="Center" Margin="0,0,0,0" Width="350" Height="900" BorderThickness="0,0,0,0" RequestedTheme="Default" VerticalAlignment="Top" FontSize="20" IsDoubleTapEnabled="False" IsHoldingEnabled="False" IsRightTapEnabled="False" Background="Transparent">
一切似乎都是正确的,但当我单击窗口对话框的一个按钮时(在选择列表框的一个元素后),窗口对话框将再次出现两次,而不是仅仅返回主窗口
有什么我遗漏的吗
谢谢正如评论中所指出的,由于您正在从列表中删除所选项目,因此将触发第二个事件
删除当前选定的项目时,SelectedIndex
设置为默认值,即-1。因此,如果用户选择了
索引X处的项目,删除项目后,它将更改为-1,因此
触发SelectedIndexChanged
事件
-1SelectedIndex
表示列表中当前没有选定项
因此,解决此问题的最简单方法就是添加一个检查,查看所选索引是否为-1
private async void SelectedIndexChanged(object sender, SelectionChangedEventArgs e)
{
int itemIndex = myList.SelectedIndex;
//checking if the selected index is -1 (or no item is actually selected)
if (itemIndex != -1)
{
var messageDialog = new MessageDialog("What do you want to do?", "Alert!");
messageDialog.Commands.Add(new UICommand("Do It", null));
messageDialog.Commands.Add(new UICommand("Don't do it", null));
messageDialog.Commands.Add(new UICommand("Cancel", null));
var cmdClick = await messageDialog.ShowAsync();
Debug.WriteLine(itemIndex);
if (cmdClick.Label == "Do It")
{
Debug.WriteLine("Do It");
myList.Items.RemoveAt(itemIndex);
return;
}
if (cmdClick.Label == "Don't do it")
{
Debug.WriteLine("No defect");
myList.Items.RemoveAt(itemIndex);
return;
}
if (cmdClick.Label == "Cancel")
{
Debug.WriteLine("Cancel");
return;
}
}
}
希望这有帮助 您选择一个项目,将触发first SelectedIndexChanged。然后在前2个
中,如果从列表中删除当前选定的项目,则选定的索引将再次更改,第二个事件为firedso,您建议如何管理此问题?
private async void SelectedIndexChanged(object sender, SelectionChangedEventArgs e)
{
int itemIndex = myList.SelectedIndex;
//checking if the selected index is -1 (or no item is actually selected)
if (itemIndex != -1)
{
var messageDialog = new MessageDialog("What do you want to do?", "Alert!");
messageDialog.Commands.Add(new UICommand("Do It", null));
messageDialog.Commands.Add(new UICommand("Don't do it", null));
messageDialog.Commands.Add(new UICommand("Cancel", null));
var cmdClick = await messageDialog.ShowAsync();
Debug.WriteLine(itemIndex);
if (cmdClick.Label == "Do It")
{
Debug.WriteLine("Do It");
myList.Items.RemoveAt(itemIndex);
return;
}
if (cmdClick.Label == "Don't do it")
{
Debug.WriteLine("No defect");
myList.Items.RemoveAt(itemIndex);
return;
}
if (cmdClick.Label == "Cancel")
{
Debug.WriteLine("Cancel");
return;
}
}
}