ListBox 和 Datasource - 防止第一个项目被选中-C#/.NET问题

ListBox and Datasource - prevent first item from being selected(ListBox 和 Datasource - 防止第一个项目被选中)

本文介绍了ListBox 和 Datasource - 防止第一个项目被选中的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

嘿.我有以下代码填充我的列表框

Hey. I've got the following code that populates my list box

UsersListBox.DataSource = GrpList;

但是，在填充该框后，默认选择列表中的第一项，并触发选择的索引已更改"事件.如何防止在填充列表框后立即选择项目，或者如何防止触发事件?

However, after the box is populated, the first item in the list is selected by default and the "selected index changed" event fires. How do I prevent the item from being selected right after the list box was populated, or how do I prevent the event from firing?

谢谢

推荐答案

为了防止事件触发，这里有两个我过去使用过的选项:

To keep the event from firing, here are two options I have used in the past:

在设置 DataSource 时取消注册事件处理程序.

Unregister the event handler while setting the DataSource.

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

创建一个布尔标志以忽略该事件.

Create a boolean flag to ignore the event.

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;

这篇关于ListBox 和 Datasource - 防止第一个项目被选中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！