Visual Studio C＃中wpf应用程序中的ListBox处理 [英] ListBox handling in wpf application in visual studio C#

问题描述

任何人都可以解释一下这段代码





ListBoxItem lbi =（listbox1.SelectedItem as ListBoxItem）;

tb1.Text = lbi.Content.ToString（）;

can any one please explain me this code


ListBoxItem lbi = (listbox1.SelectedItem as ListBoxItem);
tb1.Text = lbi.Content.ToString();

推荐答案

WPF ListBox与WinForms ListBox一样，存储了一组对象，它们是通过'Items属性访问，或者，如此处，通过访问'SelectedItem属性。



因此，'SelectedItem 返回一个对象：然后，必要将该Object转换回ListBoxItem，因此可以访问其内部字段。转换是在这里使用'as运算符完成的。



ListBoxItem的'Content字段在技术上是ContentControl依赖属性：[ ^ ]。



在这种情况下，看起来程序员预计内容字段不包含字符串，并且需要使用'ToString（）来获取字符串值。

The WPF ListBox, like the WinForms ListBox, stores a collection of Objects, which are accessed through its 'Items property, or, as in the case here, via accesing the 'SelectedItem property.

So, 'SelectedItem returns an Object: then, it's necessary to convert that Object back into a ListBoxItem, so its internal fields can be accessed. The conversion is accomplished here using the 'as operator.

The 'Content field of a ListBoxItem is technically a ContentControl dependency property: [^].

In this case, it looks like the programmer anticipated that the 'Content field did not contain a string, and required the use of 'ToString() to get a string value.

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