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Advanced Visual Basic .NET Techniques for Error Handling and Graphics

Learn how to handle errors with Try-Catch statements and utilize graphic objects for drawing in Visual Basic .NET applications. Explore creating menus and multiple forms for enhanced development.

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Advanced Visual Basic .NET Techniques for Error Handling and Graphics

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  1. Chapter 12 – Advanced Topics Chapter Objectives • Explain how to properly handle errors using Try and Catch statements • Explain how to use the graphic objects to draw on other objects • Explain how to create menus • Explain how to create applications containing multiple forms The Visual Basic .NET Coach

  2. Chapter 12 – Advanced Topics 12.1 Improved Error Handling Programs are not written without errors occurring. Generic error messages will intimidate the user of the application. You should try to prevent errors from occurring by validating input and not allowing situations to arise in code where the system does not know how to react. Predicting all possible errors cannot always be accomplished. Visual Basic .NET provides the Try, Catch, Finally block structure, allowing you to code error handling in your applications. The syntax of the new structure is as follows: Try 'Code to check for error CatchWhen Err.Number = ErrorNumber 'Code to handle specific error CatchWhen Err.Number = Another ErrorNumber 'Code to handle other specific error Catch 'Code to handle all the other errors Finally 'Code to execute directly after EndTry The Visual Basic .NET Coach

  3. Chapter 12 – Advanced Topics • Code placed in a Try-Catch structure can be checked for: • individual errors with specific code written to handle each error • all errors can be handled by one set of code • specific errors and then allow all remaining errors to be handled by one set of code. • You can think of a Try-Catch structure as similar to a Select-Case structure. • Try-Catch will trap errors for is placed between the Try keyword and the first Catch statement. • Each Catch When statement can be set up to check for specific errors by checking the exact number of the error that occurred. • If the error occurs, then the code associated with the specific Catch When statement is executed. • If you create a Catch statement without a When condition, then the code associated with the Catch statement will execute whenever none of the previous Catch When statements match the error. • After Catch statements have been evaluated and possibly executed, the Finally statement allows you to specify code that will always execute. • This code will execute whether or not an error has occurred in the code you are testing. The Visual Basic .NET Coach

  4. Chapter 12 – Advanced Topics Arithmetic Error Example Imagine if you had to perform a calculation between a series of Short variables to output the average commission, to the nearest dollar, for a salesperson over the summer. The calculation might be coded as follows: shtAverageCommision = (shtJuneSales + shtJulySales + _ shtAugustSales) / shtPeriod The calculation adds the sales of the months June, July, and August and then divides them by the variable storing the number of months in the period. There are two very obvious possible sources of error. First, remember that a Short variable can have a maximum value of 32,767. If the addition of all three months is greater than 32,767, you could get an overflow error. You also have to worry that the variable shtPeriod is not equal to zero, because if it is, you will get a divide by zero error when performing the calculation. The Visual Basic .NET Coach

  5. Chapter 12 – Advanced Topics The answer to these problems is to place the code inside a Try block as follows: Try 'Code to check for error shtAverageCommission = (shtJuneSales + shtJulySales + _ shtAugustSales) \ shtPeriod CatchWhen Err.Number = 6 'Code to handle arithmetic overflow MsgBox("Computing the average commission produced a mathematical error") 'set the average commission to a valid value shtAverageCommission = 0 Catch'Code to handle all other errors MsgBox(" An " & Err.Description & _ " error occurred when computing the average summer commission") 'set the average commission to a valid value shtAverageCommission = 0 Finally 'Code to execute directly after EndTry The Visual Basic .NET Coach

  6. Chapter 12 – Advanced Topics Open File Error Errors can often occur when a resource is unavailable. A very common resource that may be unavailable is a file. Often a file path could be wrong or another user may lock the file and your application is restricted from gaining access. When you are opening a file, you should always trap for an error. Try Dim FileStreamName AsNew FileStream("C:\Log.txt", FileMode.Open, _ FileAccess.Read) CatchWhen Err.Number = 53 MsgBox(" An error occurred when opening the log file") EndTry The Visual Basic .NET Coach

  7. Chapter 12 – Advanced Topics 12.2 Graphics You are already familiar with displaying some graphics in your applications. The picture box control allows you to display only images that were previously created. With the additional built-in objects provided in Visual Basic .NET, you have the ability to draw figures in many creative ways.  Although the initial method of using the Graphics class may seem a little cumbersome, use Visual Basic .NET’s type ahead feature to help. The Visual Basic .NET Coach

  8. Chapter 12 – Advanced Topics Using graphics starts by including the System.Drawing namespace, which will give you access to numerous classes that, when used together, allow you to draw directly on a form. Any drawing that you will accomplish will require the use of at least the Graphics and Pen objects as well as Color, Point, Rectangle, and Size objects to help specify exactly how you wish to draw. The Graphics object represents the surface you will be drawing on as well as being the object that creates graphical images. The Pen object will determine how you draw on the Graphics object. We’ll introduce these features by showing you how to create a drawing of a man. The Visual Basic .NET Coach

  9. Chapter 12 – Advanced Topics Step 1: Before you can draw anything on an object, you must create a Graphics object and then instantiate it. This is done by declaring a Graphics object and then calling a CreateGraphics method of the form. You can declare the Graphics object using the following code: Dim grfGraphics As Graphics To instantiate the object, you have to call the CreateGraphics method of the form. The easiest way to do this is to refer to the form using the Me keyword. grfGraphics = Me.CreateGraphics The Visual Basic .NET Coach

  10. Chapter 12 – Advanced Topics • Step 2: A Pen object will be used to draw with the Graphics object. • There are four ways to declare a Pen object. • The simplest is just to select a color. • If you want to get fancy, you can also select a Brush object to draw with a little more style. • While the default width of a Pen object is 1, you can also specify how wide you wish your pen to draw. • To declare a Pen object, you can use the following syntax: • DimPenNameAsNew Pen(Color.ColorName, PenWidth) • PenName: The name of the pen you are declaring and instantiating. • ColorName: One of the predefined colors you can select. • PenWidth: A single value indicating the width of the pen as it draws. The Visual Basic .NET Coach

  11. Chapter 12 – Advanced Topics When you instantiate a Pen object, you will first select the color of the pen. Selecting a color is accomplished by using the Color object. The Color object gives you access to all the predefined colors in Visual Basic .NET. Type "Color." and a list of predefined colors will pop up. When you select one of these, your color use is greatly simplified. To create your Pen object to draw a red line with a width of 2, use the following code: Dim penOurPen AsNew Pen(Color.Red, 2) With the Pen object created, you can now draw with the Graphics object. The Visual Basic .NET Coach

  12. Chapter 12 – Advanced Topics Let’s start by drawing the circular head. The easiest way to do this is to use the Ellipse method of the Graphics object. It takes a Pen as the first parameter and then the X and Y locations of the upper-left corner of a rectangle that bounds the circle or ellipse that you are drawing. The syntax is as follows: GraphicsObjectName.DrawEllipse(PenName, XLocation, YLocation, Width, Height) The final two parameters are the length and width of the bounding rectangle. The code to draw the head would be as follows: grfGraphics.DrawEllipse(penOurPen, 50, 50 , 40, 40) The Visual Basic .NET Coach

  13. Chapter 12 – Advanced Topics Step 3: To draw the body, you need to draw a straight line. The Graphics object contains a method DrawLine that will allow you to do this. Switch the color of the pen by changing the Color property of your pen. PenOurPen.Color = Color.Blue Step 4: Draw the line using the following syntax: GraphicsObjectName.DrawLine(PenName, StartingXLocation, StartingYLocation, _ EndingXLocation, EndingYLocation) The code required to draw your body can then be drawn with the following code: grfGraphics.DrawLine(penOurPen, 70, 90, 70, 150) The Visual Basic .NET Coach

  14. Chapter 12 – Advanced Topics Step 5: You can follow the same procedure to draw the arms and legs. Set the color to yellow with the following code: PenOurPen.Color = Color.Yellow Step 6: Now you can draw the left and right arms with the following code: grfGraphics.DrawLine(penOurPen, 70, 150, 55, 105) grfGraphics.DrawLine(penOurPen, 70, 150, 85, 105) Step 7: To add legs, since they are the same color, you do not have to change the Pen object. You can simply use the following code to draw the two lines representing the legs: grfGraphics.DrawLine(penOurPen, 70, 150, 45, 170) grfGraphics.DrawLine(penOurPen, 70, 150, 95, 170) The Visual Basic .NET Coach

  15. Chapter 12 – Advanced Topics Step 8: To draw the feet use the DrawRectangle method. The DrawRectangle method takes two parameters: a Pen and a Rectangle. You already have a Pen object created. To create a Rectangle object you need a Point object and a Size object. 'Draw Feet Dim rctFoot As Rectangle Dim pntFoot As Point Dim szeFoot As Size szeFoot = New Size(20, 10) 'Left Foot pntFoot = New Point(25, 160) rctFoot = New Rectangle(pntFoot, szeFoot) grfGraphics.DrawRectangle(penOurPen, rctFoot) 'Right Foot pntFoot = New Point(95, 160) rctFoot = New Rectangle(pntFoot, szeFoot) grfGraphics.DrawRectangle(penOurPen, rctFoot) The Visual Basic .NET Coach

  16. Chapter 12 – Advanced Topics Step 8 (Alternative): If you wanted to fill in the rectangle, you could use the FillRectangle method. The FillRectangle method requires a Brush object instead of a Pen object. There are many different types of brushes. You can create brushes that paint a solid color, a pattern, or even a texture using a bitmap file. For simplicity, you will create a brush with a solid color. 'Draw Feet Dim rctFoot As Rectangle Dim pntFoot As Point Dim szeFoot As Size Dim bshAdam As SolidBrush bshAdam = New SolidBrush(Color.Yellow) szeFoot = New Size(20, 10) 'Left Foot pntFoot = New Point(25, 160) rctFoot = New Rectangle(pntFoot, szeFoot) grfGraphics.FillRectangle(bshAdam, rctFoot) 'Right Foot pntFoot = New Point(95, 160) rctFoot = New Rectangle(pntFoot, szeFoot) grfGraphics.FillRectangle(bshAdam, rctFoot) The Visual Basic .NET Coach

  17. Chapter 12 – Advanced Topics • Step 9: The last step is to add text to the drawing. • You can control the font and the brush that you draw with. • The Font object can be created by specifying some or all of the parameters in the following syntax: • FontObject = New Font(FontName, FontSize, FontStyle) • FontName: Specifies the name of the font to display. • FontSize: Specifies the size of the font. • FontStyle: Specifies the style of the font (bold, italics, etc.). • To create a Font object to display the text "Adam" in a bold Times 20-point font using the previously created SolidBrush, use the following code: • Dim fntAdam As Font • bshAdam = New SolidBrush(System.Drawing.Color.Black) • fntAdam = New Font("Times", 20, FontStyle.Bold) • grfGraphics.DrawString("Adam", fntAdam, bshAdam, 32, 180) The Visual Basic .NET Coach

  18. Chapter 12 – Advanced Topics • Step 9: The last step is to add text to the drawing. • You can control the font and the brush that you draw with. • The Font object can be created by specifying some or all of the parameters in the following syntax: • FontObject = New Font(FontName, FontSize, FontStyle) • FontName: Specifies the name of the font to display. • FontSize: Specifies the size of the font. • FontStyle: Specifies the style of the font (bold, italics, etc.). • To create a Font object to display the text "Adam" in a bold Times 20-point font using the previously created SolidBrush, use the following code: • Dim fntAdam As Font • bshAdam = New SolidBrush(System.Drawing.Color.Black) • fntAdam = New Font("Times", 20, FontStyle.Bold) • grfGraphics.DrawString("Adam", fntAdam, bshAdam, 32, 180) The Visual Basic .NET Coach

  19. Chapter 12 – Advanced Topics 12.3 Creating Menus Using the Menu Editor Menus are present in almost every application. Menus make commonly used options available to the user. Observe the menu for Visual Basic .NET and the submenu and separator bars. The Visual Basic .NET Coach

  20. Chapter 12 – Advanced Topics To produce a menu, Visual Basic .NET provides the MainMenu object. When the MainMenu object is placed on the form, it will not appear on the actual form itself It will appear below it as did the objects associated with connecting to a database. When the Menu object is placed on the form, you can design your menu simply by clicking on the Menu object and then typing your menu in the Type Here boxes that appear. The Visual Basic .NET Coach

  21. Chapter 12 – Advanced Topics Once the menu name is entered, menu placeholders appear. Menu items can be placed in these placeholders, with additional placeholders appearing as each menu item is added. The Visual Basic .NET Coach

  22. Chapter 12 – Advanced Topics Once the menu name is entered, menu placeholders appear. Menu items can be placed in these placeholders, with additional placeholders appearing as each menu item is added. For each menu item, you will want to attach code to execute whenever the user selects it. To attach code, just double-click on the menu item and place the code in the Click event code that appears, in the same way you would for a button object. The Visual Basic .NET Coach

  23. Chapter 12 – Advanced Topics Example: Simple Menu Application Menus can be used to provide an easy way to access an application’s commonly used functions. To focus on your understanding of the operation of a menu, you will create an application that is as simple as possible. Your application will display a label and a picture that show a race walking competition. The application will contain two menus, one to modify the picture and one to modify the label. The application should have a menu to modify the border of the picture. It will contain menu items to add a border to the picture and another menu item to remove it. The Label menu will contain a menu item that will increase the size of the font in the label and another menu item to reduce the size of the font in the label. The menu items will be created to set the color of the text to black, blue, or red. The Visual Basic .NET Coach

  24. Chapter 12 – Advanced Topics Creating the Race Walking Application Building an Application with a Menu Step 1: Add a MainMenu object to the form. Step 2: Rename the MainMenu object to mnuRaceWalk. Step 3: Click on the MainMenu object so the window with Type Here appears. Step 4: Type "&Picture" as the title of the first menu. Step 5: Just as all controls in Visual Basic .NET have a name, so should menus. Name your Picture menu mnuPicture by typing "mnuPicture" in the Name property of the Properties window. The Visual Basic .NET Coach

  25. Chapter 12 – Advanced Topics Step 6: You need to add the menu items that belong to the Picture menu. To associate menu items with a menu, you need to first click on the Type Here box below the Picture menu so that the menu editor moves from the current menu to a space to create the menu item. Step 7: Enter the new menu item. Type "&Add Border". The Visual Basic .NET Coach

  26. Chapter 12 – Advanced Topics Step 8: Rename the menu item to mnuPictureAdd. Step 9: You can add the second menu item in the same manner. Click on the Type Here box below the mnuPictureAdd menu item and fill in &Remove Border and rename it mnuRemoveBorder. The Visual Basic .NET Coach

  27. Chapter 12 – Advanced Topics Step 10: Click to the right of the Picture menu on the MainMenu object so that you can type in the Type Here box. When you click, additional Type Here boxes will appear and the previous ones along with the Picture menu’s menu items will disappear. Step 11: Type "&Label" for the second menu. Step 12: Rename the menu to mnuLabel. The Visual Basic .NET Coach

  28. Chapter 12 – Advanced Topics Step 13: You can now specify the first menu item of the Label menu. First, you click on the Type Here box below the Label menu. Specify Text and Name properties for the menu item. In this case, the names will be &Grow and mnuLabelGrow, respectively. The Visual Basic .NET Coach

  29. Chapter 12 – Advanced Topics Step 14: You can add the remaining menu items in the same manner. Click on the Type Here box and fill in "&Shrink" and "mnuLabelShrink" for the Text and Name properties of this menu item. Repeat this process for &Black and mnuLabelBlack, &Blue and mnuLabelBlue, and &Red and mnuLabelRed. The Visual Basic .NET Coach

  30. Chapter 12 – Advanced Topics You are now complete with creating the “shell” of your menu; however, you still must specify the code that will execute when the individual menu items are selected. Adding the Label and Picture Box This application would really be about nothing if you didn’t add a few controls to manipulate the menu items. Add a label and picture box control titling and showing a race walking event. Step 1: Add a label control drawn as wide as the form. Step 2: Change the Name of the label control to lblTitle. Step 3: Change the Text of the label control to Race Walking Competition. Step 4: Change the TextAlign to MiddleCenter. Step 5: Change the FontStyle to Bold. Step 6: Resize the form to fit an image 400 x 400 pixels wide. Step 7: Add a picture box control to the form and size it so that it can fit an image. Step 8: Change the Name of the picture box to picRaceWalk. Step 9: Click on the Image property and select the RaceWalk.jpg file in the bin directory. The Visual Basic .NET Coach

  31. Chapter 12 – Advanced Topics You are now complete with creating the “shell” of your menu; however, you still must specify the code that will execute when the individual menu items are selected. Adding the Label and Picture Box This application would really be about nothing if you didn’t add a few controls to manipulate the menu items. Add a label and picture box control titling and showing a race walking event. Step 1: Add a label control drawn as wide as the form. Step 2: Change the Name of the label control to lblTitle. Step 3: Change the Text of the label control to Race Walking Competition. Step 4: Change the TextAlign to MiddleCenter. Step 5: Change the FontStyle to Bold. Step 6: Resize the form to fit an image 400 x 400 pixels wide. Step 7: Add a picture box control to the form and size it so that it can fit an image. Step 8: Change the Name of the picture box to picRaceWalk. Step 9: Click on the Image property and select the RaceWalk.jpg file in the bin directory. The Visual Basic .NET Coach

  32. Chapter 12 – Advanced Topics Specifying Code to Execute Each menu item has a Click event for which you can specify code to accomplish whatever the purpose of the menu item is. Step 1: By clicking on the menu and then the menu item you desire, you will call up the Click event code for that menu item. The Visual Basic .NET Coach

  33. Chapter 12 – Advanced Topics PrivateSub mnuPictureAdd_Click(… EndSub Menu item Click event code Step 2: Now you can just add your code to set a border around your picture: PrivateSub mnuPictureAdd_Click(… 'Change the border style to a fixed 3D border picRacewalk.BorderStyle = BorderStyle.Fixed3D EndSub Step 3: To add the code to the menu item mnuRemoveBorder, you just repeat the process. PrivateSub mnuPictureRemove_Click(… 'Remove the border style by setting it to None picRacewalk.BorderStyle = BorderStyle.None EndSub The Visual Basic .NET Coach

  34. Chapter 12 – Advanced Topics Step 4: Repeat this process for the remaining menu items: mnuLabelGrow, mnuLabelShrink, mnuLabelBlack, mnuLabelBlue, and mnuLabelRed. PrivateSub mnuLabelGrow_Click(… 'Increase the Font by creating a new Font from the current Font 'with a font size of 1 greater than the font lblTitle.Font = New Font("Microsoft Sans Serif", lblTitle.Font.Size + 1, _ FontStyle.Bold) EndSub PrivateSub mnuLabelShrink_Click(… 'Increase the Font by creating a new Font from the current Font 'with a font size of 1 less than the font lblTitle.Font = New Font("Microsoft Sans Serif", lblTitle.Font.Size - 1, _ FontStyle.Bold) EndSub PrivateSub mnuLabelBlack_Click(… 'Change the font to the color black lblTitle.ForeColor = Color.Black EndSub PrivateSub mnuLabelBlue_Click(… 'Change the font to the color blue lblTitle.ForeColor = Color.Blue EndSub PrivateSub mnuLabelRed_Click(… 'Change the font to the color red lblTitle.ForeColor = Color.Red EndSub The Visual Basic .NET Coach

  35. Chapter 12 – Advanced Topics When you are done, the application will look like: The Visual Basic .NET Coach

  36. Chapter 12 – Advanced Topics Adding a Separator Line As menu controls grow in size, it is often helpful to divide them into groups of common functionality by separator lines. A separator line would be helpful to divide the menu items to change the size of the font from those that change the color of the font. To add a separator line, just place a hyphen in the Type Here box of the menu editor. The Visual Basic .NET Coach

  37. Chapter 12 – Advanced Topics Adding a Submenu Although a separator line is a good way of breaking up a large menu, at some point too many menu items under one menu becomes cumbersome. A submenu is an excellent way to combat this. The Visual Basic .NET Coach

  38. Chapter 12 – Advanced Topics Creating a Submenu Previously, you were told to ignore the Type Here box to the right of menu items. By typing in them, you can create a submenu. Step 1: Change the first Label menu item’s Name and Text properties to mnuLabelSize and Change Size, respectively. Step 2: Click on the Type Here box to the right of the mnuLabelSize menu item. Step 3: Set the Name and Text properties to mnuLabelSizeGrow. and &Grow. Step 4: Click on the Type Here box below the mnuLabelSizeGrow menu item. Step 5: Set the Name and Text properties to mnuLabelSizeShrink. and &Shrink. Step 6: To create the second submenu, click below the mnuLabelSize menu item in the Type Here box. Step 7: Set the Name and Text properties to mnuLabelColor. and Change &Color. Step 8: Click on the Type Here box to the right of the mnuLabelColor menu item. Step 9: Set the Name and Text properties to mnuLabelColorBlack. and &Black. Step 10: Repeat the process for the remaining submenu items. The Visual Basic .NET Coach

  39. Chapter 12 – Advanced Topics Creating a Submenu The Visual Basic .NET Coach

  40. Chapter 12 – Advanced Topics 12.4 Multiple Form Applications All of the applications you have developed so far have been limited to a single form or an SDI (Single Document Interface). This limits the functionality of your applications. You will first start with a simple application that does not consider the many issues that arise when you use applications with more than one form. Showing Another Form To open another form from the current form is a simple matter of using the Show method of a form. The syntax is as simple as FormName.Show The Visual Basic .NET Coach

  41. Chapter 12 – Advanced Topics Hiding or Unloading a Form Once a form has been loaded, you can make the form disappear two ways. If you want the form to merely disappear from the screen but still remain in memory, use the Hide event. The syntax for hiding a form is as follows: FormName.Hide The other option for making a form disappear is to remove it both from the screen and the computer’s memory. This is accomplished with the Unload command. When a form is unloaded, unless the information that was entered into it is saved elsewhere, it will be lost. The syntax for unloading a form is as follows: Me.Close() The Visual Basic .NET Coach

  42. Chapter 12 – Advanced Topics Example: Personnel Information Now that you can create an application with more than one form, you can increase the amount of information you can gather in a single application. For simplicity, you will create an application that gathers personnel information, but it will not save the information anywhere. The case study at the end of the chapter will demonstrate that. Your application will contain three forms: frmPersonnel, frmDemographics, and frmFinancial. Each will contain different information about a person working for a company. The first form that the user will be presented with is frmPersonnel. The Visual Basic .NET Coach

  43. Chapter 12 – Advanced Topics The Personnel form is the main form of your application. It is the form that will be presented to the user when the application starts. From it, you will be able to call both the Demographics and Financial forms. These forms will be displayed when the btnDemographics or btnFinancialbuttons are clicked. The btnProfit button will display a message box containing information from the additional forms of the application. The Visual Basic .NET Coach

  44. Chapter 12 – Advanced Topics The Demographics form will contain an individual’s demographic information. Notice that we have displayed information from the frmPersonnel form (my name) and added the btnHide button. The btnHide button will allow the user to remove the form from the computer screen without removing it from the computer’s memory. The Visual Basic .NET Coach

  45. Chapter 12 – Advanced Topics The Financial form will contain an individual’s financial information. Your Financial form contains text boxes to enter the number of hours and the rate at which an individual billed and worked. Typically, consultants may work more hours than they can bill. Consultants will be billed out at a higher rate than they are getting paid. The Visual Basic .NET Coach

  46. Chapter 12 – Advanced Topics Sharing Data Across Multiple Forms While the code to instantiate and open the additional forms is rather trivial, a bit more thought is required in coding your application to share data across forms. If you try to access an object on one form from another form, you will get a scoping error. Objects created on one form are scoped to Private by default. You will require the frmDemographics form’s txtTitle’s Text value to be accessible from the Personnel form. You will wish to make the txtHomePhone’s Text value accessible. The easiest way to accomplish this is to add a series of Property statements to the frmDemographics form giving access to the required properties. PublicProperty Title() AsString Get Return lblTitle.Text EndGet Set(ByVal Value AsString) lblTitle.Text = Value EndSet EndProperty PublicProperty HomePhone() AsString Get Return txtHome.Text EndGet Set(ByVal Value AsString) txtHome.Text = Value EndSet EndProperty The Visual Basic .NET Coach

  47. Chapter 12 – Advanced Topics On the frmFinancial’s form, you will require access to the txtTitle’s Text value as well as the profit amount. Create a property called Profit that is automatically calculated when accessed. PublicProperty Title() AsString Get Return lblTitle.Text EndGet Set(ByVal Value AsString) lblTitle.Text = Value EndSet EndProperty PublicProperty Profit() AsString Get 'Profit = Billables - Payables Return (FormatCurrency((Val(txtBHours.Text) * Val(txtBRate.Text)) - _ (Val(txtPHours.Text) * Val(txtPRate.Text)))) EndGet Set(ByVal Value AsString) 'Nothing happens, can't set the profit directly EndSet EndProperty The Visual Basic .NET Coach

  48. Chapter 12 – Advanced Topics Calling and Hiding Forms The frmPersonnel form is the driver of the application. It will instantiate and call an instantiation of the frmDemographic and frmFinancial forms. Since the instances of the form will be accessed from more than one place in the frmPersonnel form, it is necessary to create a property for each to prevent the developer from making them visible to the entire form. Add the following code in the form’s declaration section: Private frmDemo As frmDemographics Private frmFinance As frmFinancials The Visual Basic .NET Coach

  49. Chapter 12 – Advanced Topics While the previous code declares the objects of each form, it does not instantiate them. Each form will be instantiated when the user clicks on the button associated with each form. In addition to instantiating them, the code will also set the Title property you created for the form so that it is personalized with the name of the person specified on the frmPersonnel form. The final step is to display the newly instantiated and initialized form. The code for both buttons follows: PrivateSub btnDemographics_Click(… frmDemo = New frmDemographics() frmDemo.Title = "Demographics for " & txtFirstName.Text & _ " " & txtLastName.Text frmDemo.Show() EndSub PrivateSub btnFinancial_Click(… frmFinance = New frmFinancials() frmFinance.Title = "Financials for " & txtFirstName.Text & " " & _ txtLastName.Text frmFinance.Show() EndSub The Visual Basic .NET Coach

  50. Chapter 12 – Advanced Topics While the previous code declares the objects of each form, it does not instantiate them. Each form will be instantiated when the user clicks on the button associated with each form. In addition to instantiating them, the code will also set the Title property you created for the form so that it is personalized with the name of the person specified on the frmPersonnel form. The final step is to display the newly instantiated and initialized form. The code for both buttons follows: PrivateSub btnDemographics_Click(… frmDemo = New frmDemographics() frmDemo.Title = "Demographics for " & txtFirstName.Text & _ " " & txtLastName.Text frmDemo.Show() EndSub PrivateSub btnFinancial_Click(… frmFinance = New frmFinancials() frmFinance.Title = "Financials for " & txtFirstName.Text & " " & _ txtLastName.Text frmFinance.Show() EndSub The Visual Basic .NET Coach

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