自定义事件在调用时始终显示为空

本文介绍了自定义事件在调用时始终显示为空的处理方法，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

我在C Sharp(Silverlight)中编写了一个自定义事件.这是代码.

Hi, I wrote a custom event in C sharp(Silverlight).Here is the code.

public delegate void MyEvent(object sender, TreeGridEventArgs e); public event MyEvent SLTreeGridSelectionChanged; void RaiseSLTreeGridSelectionChanged(TreeGridEventArgs e) { if (SLTreeGridSelectionChanged != null) { SLTreeGridSelectionChanged(this, e); } }

在这里我将调用它(在DataGrid的SelectionChanged事件期间) ..

and here I will invoke it( during the SelectionChanged event of DataGrid) ..

private void SLDataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e) { if (CurrentSELedNode != null) { TreeGridRow row = (TreeGridRow)CurrentSELedNode.Tag; RaiseSLTreeGridSelectionChanged(new TreeGridEventArgs(row)); } }

但是在引发事件时，"SLTreeGridSelectionChanged"始终显示为null.为什么会这样呢?任何的想法..?请帮助我..

but while raising the event "SLTreeGridSelectionChanged" always shows null. Why this is happening? Any idea..? Please help me..

推荐答案

只要没有订阅者，事件为null.如果您创建事件处理程序并使用+ =语法订阅事件，它将不再是null. The event is null as long as there are no subscribers. If you create an event handler and use the += syntax to subscribe for the event, it won''t be null any more.