NetworkAddressChangedEventHandler Delegate

References one or more methods to be called when the address of a network interface changes.

Namespace:  System.Net.NetworkInformation
Assembly:  System.Net (in System.Net.dll)

'Declaration
Public Delegate Sub NetworkAddressChangedEventHandler ( _
	sender As Object, _
	e As EventArgs _
)

Parameters

sender
Type: System.Object
The source of the event.
e
Type: System.EventArgs
An EventArgs object that contains data about the event.

This delegate handles NetworkAddressChanged events raised by the NetworkChange class. For detailed information on receiving notification for network interface address change events, see the NetworkChange class overview documentation

The sender parameter passed to this event handler is always Nothing. The EventArgs object in the e parameter passed to this event handler is always empty. These parameters are not needed, since an application receiving this event can call the GetIsNetworkAvailable static method to determine network availability.

The following example uses a NetworkAddressChangedEventHandler to handle NetworkAddressChanged events and detect when network availability changes.


Public class Example

    Dim Shared online As Boolean = False

    Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
        ' Initialize the online variable and set a NetworkChange handler
        SetupNetworkChange()

        outputBlock.Text &= "Network is: "
        If online Then
            outputBlock.Text &= "online"
        Else   
            outputBlock.Text &= "offline"
        End If    

        ' Now start the main work of the application        
    End Sub

    ' Subroutine that gets called when the network changes 
    Private Shared Sub OnNetworkChange (ByVal sender As object, _
       ByVale AS EventArgs)

       If NetworkInterface.GetIsNetworkAvailable() Then
           If Not online Then
              online = True
              ' do what is needed to GoOnline()
           End If
       Else 
           If online Then
               online = False
               ' do what is needed to GoOffline()
           End If
       End If
    End Sub

    Private Shared Sub SetupNetworkChange()
        ' Get current network availalable and store the 
        ' initial value for online value
        If NetworkInterface.GetIsNetworkAvailable() Then
            online = true
            ' do what is needed to GoOnline()
        Else    
            online = false
            ' do what is needed to GoOffline()
        End If    

        ' Now add a network change event handler to indicate
        ' network availability 
        AddHandler NetworkChange.NetworkAddressChanged , _
            AddressOf OnNetworkChange
    End Sub

End Class  


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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