Question

以下代码生成ArgumentNullException：

Public Custom Event PlayerDetailRequested As RoutedPropertyChangedEventHandler(Of Player)

    AddHandler(ByVal value As RoutedPropertyChangedEventHandler(Of Player))
        Me.AddHandler(PlayerDetailRequestedEvent, value)
    End AddHandler

    RemoveHandler(ByVal value As RoutedPropertyChangedEventHandler(Of Player))
        Me.RemoveHandler(PlayerDetailRequestedEvent, value)
    End RemoveHandler

    RaiseEvent(ByVal sender As Object, ByVal e As RoutedPropertyChangedEventArgs(Of Player))
        Me.RaiseEvent(e)
    End RaiseEvent
End Event

Public Shared ReadOnly PlayerDetailRequestedEvent As RoutedEvent = _
                  EventManager.RegisterRoutedEvent("PlayerDetailRequested", _
                  RoutingStrategy.Bubble, _
                  GetType(RoutedPropertyChangedEventHandler(Of Player)), GetType(PlayersManagementControl))



  Private Sub Hyperlink_Click(sender As Object, e As RoutedEventArgs)
        RaiseEvent PlayerDetailRequested(Me, New RoutedPropertyChangedEventArgs(Of Player)(SelectedPlayer, SelectedPlayer))
    End Sub

调用Me.RaiseEvent(e)

时会抛出异常

很难找到VB中的工作示例和C sharp的事件处理是不同的。请帮助我保持理智！

Answer 1

问题在Exception：Value cannot be null. Parameter name: routedEvent中解释。 RoutedEvent是RoutedEventArgs的属性。您必须提供正在筹集的RoutedEvent个实例，在您的情况下，它是PlayerDetailRequestedEvent。试试这段代码：

    Private Sub Button_Click_1(sender As Object, e As RoutedEventArgs)
            Me.RaiseEvent(New RoutedPropertyChangedEventArgs(Of Player)(SelectedPlayer, SelectedPlayer, PlayerDetailRequestedEvent))
    End Sub

调用RoutedEvent时的ArgumentNullException

1 个答案: