问题
How do I pass a value from BackgroundWorker
DoWork
to BackgroundWorker
Completed
? Since BackgroundWorker
Completed
is not called by BackgroundWorker
DoWork
I am not sure how to do this except declare a public variable
. Essentially, I want BackgroundWorker
Completed
to accept through ByVal
a variable from BackgroundWorker
DoWork
.
回答1:
When you declare your DoWork
function, note that it has some handy arguments built in :
Private Sub backgroundWorker1_DoWork(sender As Object, e As DoWorkEventArgs) _
Handles backgroundWorker1.DoWork
and also note similar arguments for the RunWorkerCompleted
handler :
Private Sub backgroundWorker1_RunWorkerCompleted(ByVal sender As Object, _
ByVal e As RunWorkerCompletedEventArgs) _
Handles backgroundWorker1.RunWorkerCompleted
Critically, you have access to e.Result
, which can be any object, in the RunWorkerCompletedEventArgs
, and also e.Result
in your DoWorkEventArgs
- the latter is passed to the former when the method completes so at the end of your worker method just set :
e.Result = myResult
and then in your RunWorkerCompleted
handler you can access it also via :
if e.Result = (whatever) then
.... etc
Reference :
RunWorkerCompletedEventArgs.Result Property : MSDN
DoWorkEventArgs.Result Property : MSDN
来源:https://stackoverflow.com/questions/17936438/pass-values-from-backgroundworker-dowork-to-backgroundworker-completed