2nd Form Load interupted by 1st forms calling event

[bglazierjr]

Hello Everyone,

Going a little crazy looking for an answer.

There are two forms, Search and View. Search is the startup form and has a button linking to View. My problem is that my view form does not complete it's FormLoad event when called from Search, it however behaves fine when made the startup form, bypassing Search altogether. I have tried several OnClick events for my button in Search but nothing seems to make a difference. Currently I am using:
View.Show()
Me.Hide()

When I try to debug, the program counter begins cycling through all the form load events of View, calling a few Subroutines but on the last Subroutine it breaks away early and ends up at Me.Hide() in the button event. Once the button event finishes the debug stops and the form is partially loaded.

From what I can tell it has nothing to do with the subroutine that it halts on. Anyone farmiliar with this issue and have any advice?

Thanks a lot!

[4x2y]

on the last Subroutine it breaks away early and ends up at Me.Hide() in the button event.

Maybe an error occurs in that sub but you don't catch it properly.

To know what's going on,
1- Put the cursor at the first line of the last sub and press F9 to add break point.
2- Run the program
3- When the program stop, continue press F8 to see which line cause unexpected break.

[bglazierjr]

Thanks but I did step through many many times. It seems to be a matter of timing rather than a particular piece of code. If I move code around an add code, remove code, it's breaks at different places everytime, never the same place. I feels like it shows the form, activates the events, executes some of the event before it is pulled away to deal with the button event.

[Shaggy Hiker]

Wrap the code in the Load event in a Try...Catch block and see whether you are getting exceptions. Whenever anybody talks about odd behavior in the Load event, it generally indicates one thing, and this just looks like another case: On certain setups (I think it may just be 64-bit OS), exceptions thrown in the Load event handler don't do anything other than exit the handler. You won't see the exception, the event handler will just exit abruptly. That kind of sounds like what you are seeing, so the Try...Catch block will tell you whether you are getting an exception.

[bglazierjr]

Thanks Shaggy,

It is Win7 64bit. I will try that tomorrow and post my results!

[Shaggy Hiker]

That makes it virtually certain to be the case.

The odd behavior of the Load Event is technically not a bug, but a disagreement between the OS and VS divisions of MS (OS & VS in MS), and seems likely to never be resolved. The manifestations can be totally perplexing, and it is a bit hard to say whether you are really seeing a case of this or not, so the easiest test is to put in the exception trap and see if you catch anything.

[DataMiser]

I have also saw this happen in a service on the 64 bit OS, took me a while to figure out what was going on. No errors were thrown and the service continued running but sometimes was not executing the entire code before exiting the sub. I went back and added a few try catch blocks and the problem went away. I also added code to log what and where the error was but the custom has never reported back on the issue. They just said the problem was solved and that was the end of it. I am still wondering what actually was happening there.

[bglazierjr]

That did it! The Try Catch revealed an attempt to parse a null into a string. Not sure why I didn't think of this as I have had to use Try Catch for this exact same situation before.....

Thanks again guys!

[Shaggy Hiker]

That doesn't sound like a situation where Try...Catch is needed. Exception handling is slow, so if you can avoid it, do so (it's only slow if an exception is thrown, it isn't slow otherwise). If it is Null, check for that with IsDBNull rather than using the exception handling.

[bglazierjr]

I only put the try catch in there for troubleshooting purposes. I was using IsDBNull but like an idiot.

Dim Val as string
Val = result.items(0)
If ISDBNull(Val) then Val = "1"
Listbox9.Items.Add(Val)

X.x assigned value to string before checking null lol counter
productive. Fixed it though, thanks again