Windows Form VB 2010

[BobbyStrain]

I have a windows form with code in VB 2010, developed with VS 2010. I upgraded it from an earlier VB version. There is a message box in a procedure that runs with a button click. But this message box shows on form load before the form is visible. If I remove the message box, the form loads as expected. What can be wrong? Bobby

[Lost User]

BobbyStrain wrote:

What can be wrong?

Anything at all. But you need to show the code that has the problem if we are to help you.

[BobbyStrain]

Here is the form load and button click code. Only relevant code shown on button click.

Private Sub HoSepForm_Load(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load

    'Plug in default values when the form loads
    txtVaporViscosity.Text = CStr(0.01)
    txtLiquidViscosity.Text = 0.5
    ddlVesselConfig.SelectedIndex = 0
    ddlVesselTypes.SelectedIndex = 0
    spnLiquidSurge.Value = 10
    txtDesignPressure.Text = CStr(250)
    cmdKOType.Text = "Process Separator"
    cmdConfig.Text = "1 Inlet & 1 Outlet"
    cmdMaterial.Text = "CS"
    cmdDiameterIncrease.Visible = False
    cmdDiameterDecrease.Visible = False
    txtVaporFlow.Text = 300000
    txtLiquidFlow.Text = 100000
    txtVaporDensity.Text = 0.5
    txtLiquidDensity.Text = 50
    txtTemperature.Text = 110
    txtOperatingPressure.Text = 200
    txtWaterFlow.Text = 10000
    ckDemister.Checked = False
    lstDropSize.SelectedIndex = 0
    ddlDemister\_h.SelectedIndex = 0
    ddlDemister\_h.Visible = False
    ddlDemisterDim.Visible = False
    Label23.Visible = False

End Sub

Sub cmdSize_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdSize.Click
(dim and some code)
'Capture all the input parameters & values
SepType = cmdKOType.Text
Material = cmdMaterial.Text
DesignPressure = Val(txtDesignPressure.Text)
VaporMassFlow = Val(txtVaporFlow.Text)
LiquidMassFlow = Val(txtLiquidFlow.Text)
VaporDensity = Val(txtVaporDensity.Text)
LiquidDensity = Val(txtLiquidDensity.Text)
VaporVisc = Val(txtVaporViscosity.Text)
'LiquidVis = Val(txtLiquidViscosity.Text)
DropSize = Val(lstDropSize.Text)
HoldTime = Val(lblLiquidSurge.Text)
OpTemperature = Val(txtTemperature.Text)
WaterRate = Val(txtWaterFlow.Text)

    'Validate that the input is complete
    If VaporDensity \* LiquidDensity \* VaporVisc \* DropSize > 0 Then
        'Input complete, so calculate drop settling velocity
        DropSpeed = Calculate\_Drop\_V(DropSize, VaporDensity, LiquidDensity, VaporVisc)
        'Then stick it in the output label on the form
        lblDropSpeed.Text = CStr(System.Math.Round(DropSpeed, 2))
        'Calculate vapor/liquid volumetric flow & holdup volume
        CFSV = VaporMassFlow / Va

[Dave Kreskowiak]

...and? That's the expected behavior. Form_Load fires before the form is rendered on screen. Are you perhaps looking for the Form_Shown event?

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Dave Kreskowiak

[BobbyStrain]

Dave, Looking at the code you will see that the message box is not in the form load event, but in a button click event. The button is on the form. I have lots of projects like this one and have never before encountered this behavior. Bobby

[Dave Kreskowiak]

Your code doesn't make any sense. Is the button Click event and the Load event handles in the same form? If so, what are you doing to call the Click handler without the form being visible? Unless you've done something very f'ed up in your code it is not possible for THAT messagebox line to be executed when you say it is.

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Dave Kreskowiak

[BobbyStrain]

Dave, Your question is exactly the one I am looking to answer. There is no call to the button click event. So, I wonder where the call might be coming from. When I remove the message box from the button click event everything works as it should and the form loads. Bobby

[Dave Kreskowiak]

We can't see your code so it's up to you to find the problem. I'd start by putting a breakpoint in the top of the button Click event handler and running the code. Look at the Call Stack to see where the call came from.

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Dave Kreskowiak

[BobbyStrain]

Dave, The call is from a radio button, but I have no idea where the call originates. It must be buried somewhere within the VS generated code. So I will give up and simply remove the message box. Thanks for your advice. Bobby

[Dave Kreskowiak]

Yeah I seriously doubt it's in the designer generated code. It won't reference anything in your event handlers, ever. This is a sign you've got something really messed up in your code and the stack trace is your best bet for finding it. I'd take a careful look at every method listed in the stack trace.

A guide to posting questions on CodeProject

Click this: Asking questions is a skill. Seriously, do it.
Dave Kreskowiak

[Lost User]

BobbyStrain wrote:

The call is from a radio button

Whereabouts on the form is this button, and does it get initialised somewhere? You should go back to the designer and check all the properties and events of the button, it is obviously firing for some reason. And, as Dave K. says, breakpoints and stack traces should find the issue fairly quickly.

[BobbyStrain]

Richard, I have replaced the radio buttons with checkboxes. The checkboxes are not linked, but they are located within a group box. I modified things such that the checkbox is disabled and unchecked initially. It is activated and checked at the end of the form load code. I don't get the message anymore because the form load fills in all the input data. The checkbox checked change event is still firing on form load which fires the calculation, too. I don't have a clue as to how to run a stack trace, but I guess I will need to learn. We have come a long way since I started using Microsoft basic in 1982 with an 8-bid Z-80 4 mh processor. I have lots of small applications using VB.net and this is the first time I have encountered such mysterious behavior. It probably is related to upgrading with VS 2010. Thanks for your help. And you, too, Dave. Bobby

[Lost User]

BobbyStrain wrote:

I don't have a clue as to how to run a stack trace, but I guess I will need to learn.

Set a breakpoint in the source code window (click in the margin by the first line of code) of Visual Studio and press F5 to run the program in the debugger. When it stops at the debug point you can single step through the code, line by line, and inspect and change the variables, so you can see exactly what is happening. The debugger is probably the most useful tool at your disposal, so you should really get familiar with it. MSDN has some help information about it at https://msdn.microsoft.com/en-us/library/ms172744.aspx[^].

[BobbyStrain]

After further study, the checkbox change event is triggered during form load. So its handler is executed. I didn't realize that this is normal behavior. I already have a hidden label on the form that is used for another purpose, so I set the text during form load before enabling the checkbox, then skipped the message box display in the handler based on the value. I don't understand enough about senders and sender arguments, but this is probably the professional approach. So I learned a few new things. Thank you both. Bobby