Code to Launch, Navigate, and Check for Errors

Provided by: Dan Haught, FMS Executive Vice President

Using Visual Basic .NET, you can use Start method of the System.Diagnostics.Process class to launch an external program. Additionally, you can use the new Try/Catch syntax to check for errors. The following code sample, from our Total .NET SourceBook product, shows how to do this.

Public Sub LaunchURLWithChecks()
  ' Launch the currently installed web browser, sent
  ' it to a specified page, and check the status.
  '
  Dim MyURL As String = "http://www.fmsinc.com"
  ' Use the Try keyword to set up exception (i.e. error) handling
  Try
    ' To do this, we use start a new process and pass it the URL.
    System.Diagnostics.Process.Start(MyURL)
 
    ' If an execption occurs, the Catch block will run
  Catch noBrowser As System.ComponentModel.Win32Exception _
    When noBrowser.ErrorCode = -2147467259

    MessageBox.Show(noBrowser.Message)

  Catch other As System.ComponentModel.Win32Exception
    MessageBox.Show(other.Message)

  End Try

End Sub

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