Lab 2: The Virtual Doughnut Factory

Lab 2: The Virtual Doughnut Factory

In this lab, you will create the user interface for a Virtual Doughnut Factory application in either Visual Basic .NET or Visual C#. Your application will serve as a storefront and control panel for an automated doughnut factory. You will add controls, menus, and implement validation. The solution to this lab is available on the Supplemental Course Materials CD-ROM in the \Labs\Ch02\Solution folder.

Before You Begin

There are no prerequisites to completing this lab.

Estimated lesson time: 60 minutes

Exercise 2.1: Creating the User Interface

In this exercise, you will create the user interface by adding controls to the Virtual Doughnut Factory inventory form.

To create a new project

1. Select Visual Basic .NET or Visual C# as your preference. Open a new Windows Application project, and name it Virtual Doughnut Factory.

2. The project is opened with one form. In Solution Explorer, click Form1. The Properties window displays the File properties for Form1. Change the File Name property to frmMain.vb or frmMain.cs as appropriate.

3. Set the properties listed in Table 2.5.

   Table 2-5. Properties of the Initial Form

   Object	Property	Value
   Form1	Name	frmMain
   	Text	Virtual Doughnut Factory
   	Size	480, 400 (approximately)
   Virtual Doughnut Factory (Visual Basic .NET only)	Startup Object	frmMain

4. If you are using Visual C#, locate static void Main() and change it so that it reads as follows:

   Visual C#

   static void Main() { Application.Run(new frmMain()); }

5. Add the controls listed in Table 2.6 to the form.

   Table 2-6. Controls and Properties for frmMain

   Control	Control Type	Property	Value
   Label1	Label	Name	lblTitle
   		Text	Current Inventory
   		Font.Size	14
   		Font.Bold	True
   Label2	Label	Name	lblRaised
   		Text	Raised
   Label3	Label	Name	lblCake
   		Text	Cake
   Label4	Label	Name	lblFilled
   		Text	Filled
   Label5	Label	Name	lblGlazedRaised
   		Text	Glazed
   TextBox1	TextBox	Name	txtGlazedRaised
   		Text	<blank>
   		ReadOnly	True
   Label6	Label	Name	lblSugarRaised
   		Text	Sugar
   TextBox2	TextBox	Name	txtSugarRaised
   		Text	<blank>
   		ReadOnly	True
   Label7	Label	Name	lblChocolateRaised
   		Text	Chocolate
   TextBox3	TextBox	Name	txtChocolateRaised
   		Text	<blank>
   		ReadOnly	True
   Label8	Label	Name	lblPlainCake
   		Text	Plain
   TextBox4	TextBox	Name	txtPlainCake
   		Text	<blank>
   		ReadOnly	True
   Label9	Label	Name	lblChocolateCake
   		Text	Chocolate
   TextBox5	TextBox	Name	txtChocolateCake
   		Text	<blank>
   		ReadOnly	True
   Label10	Label	Name	lblSugarCake
   		Text	Sugar
   TextBox6	TextBox	Name	txtSugarCake
   		Text	<blank>
   		ReadOnly	True
   Label11	Label	Name	lblLemonFilled
   		Text	Lemon
   TextBox7	TextBox	Name	txtLemonFilled
   		Text	<blank>
   		ReadOnly	True
   Label12	Label	Name	lblGrapeFilled
   		Text	Grape
   TextBox8	TextBox	Name	txtGrapeFilled
   		Text	<blank>
   		ReadOnly	True
   Label13	Label	Name	lblCustardFilled
   		Text	Custard
   TextBox9	TextBox	Name	txtCustardFilled
   		Text	<blank>
   		ReadOnly	True
   Label14	Label	Name	lblSale
   		Text	Current Sale
   Label15	Label	Name	lblQuantity
   		Text	Quantity
   Label16	Label	Name	lblType
   		Text	Type
   Label17	Label	Name	lblPrice
   		Text	Price
   TextBox10	TextBox	Name	txtQuantity
   		Text	0
   ComboBox1	ComboBox	Name	cmbType
   		Text	<blank>
   TextBox11	TextBox	Name	txtPrice
   		Text	<blank>
   		ReadOnly	True
   ListBox1	ListBox	Name	lstSale
   Label18	Label	Name	lblTotal
   		Text	Total
   TextBox12	TextBox	Name	txtTotal
   		Text	<blank>
   		ReadOnly	True
   Button1	Button	Name	btnAddToSale
   		Text	Add To Sale
   Button2	Button	Name	btnRemoveItem
   		Text	Remove Item
   Button3	Button	Name	btnCheckOut
   		Text	Check Out

6. In the Properties window, add the following strings to the Items collection of cmbType: Raised-Glazed, Raised-Sugar, Raised-Chocolate, Cake-Plain, Cake-Chocolate, Cake-Sugar, Filled-Lemon, Filled-Grape, Filled-Custard.

   When all of the controls have been added, position them in logical groupings according to function. Figure 2.11 represents a possible layout for your controls.

   

   Figure 2-11. The user interface with controls added.

Exercise 2.2: Adding a Menu

In this exercise, you will use the MainMenu component to add a menu bar to your form and create an event handler for the Click event of the Exit menu item.

To add a menu to the project

1. In the Toolbox, double-click the MainMenu component. A MainMenu component is added to the component tray of the designer, and a menu box is added to the form.

2. In the menu box, type &File.

3. A menu item is added to the menu bar, and new menu boxes are added below and to the right of the menu item. The ampersand (&) provides an access key to the menu. In the Properties window, name this menu item mnuFile.

4. Repeat Step 2 to create the menu structure shown in Table 2.7. Indented items are subordinates of the item in the preceding step.

   Table 2-7. Menu Item Properties

   Menu Item	Name
   &File	mnuFile
   E&xit	mnuExit
   &Doughnuts	mnuDoughnuts
   &Make	mnuMake
   &Remove Stale	mnuRemoveStale
   &Customers	mnuCustomers
   &Add a Customer	mnuAddaCustomer
   &View Customers	mnuViewCustomers
   &Help	mnuHelp
   &About	mnuAbout
   &Contents	mnuContents

To create an event handler for the Exit menu item

1. In the designer, double-click the Exit menu item. The code window opens to the mnuExit_Click event handler.

2. Call the Close method of the form to create the event handler. For example:

   Visual Basic .NET

   Private Sub mnuExit_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles mneExit.Click Me.Close() End Sub

   Visual C#

   private void mnuExit_Click(object sender, System.EventArgs e) { this.Close(); }

3. Save and test the application.

Exercise 2.3: Creating Validation Handlers

In this exercise, you will use the ErrorProvider component to implement simple validation handlers for txtQuantity. In future labs, you will add additional validation to your form.

To create validation handlers with Visual Basic .NET

1. In the Toolbox, double-click the ErrorProvider component. An ErrorProvider is added to the component tray in the designer.

2. Right-click the designer, and choose View Code to open the code editor. In the code editor, select txtQuantity in the left drop-down menu and KeyPress in the right drop-down menu. An empty event handler for txtQuantity_KeyPress appears in the code editor.

3. Write code that will display an error if non-numeric characters are entered into the text box.

   Visual Basic .NET

   Private Sub txtQuantity_KeyPress(ByVal sender As Object, _ ByVal e As System.Windows.Forms.KeyPressEventArgs) _ Handles txtQuantity.KeyPress If Char.IsDigit(e.KeyChar) = False Then ErrorProvider1.SetError(txtQuantity, _  "Please enter a numeric value") Else ErrorProvider1.SetError(txtQuantity, "") End If End Sub

4. In the drop-down menu on the left, choose txtQuantity, and in the drop-down menu on the right, choose Validating. An empty event handler is added to the code editor.

5. Add code to validate that the txtQuantity field is not empty and has no other errors on it. For example:

   Visual Basic .NET

   Private Sub txtQuantity_Validating(ByVal sender As System.Object, _ ByVal e As System.ComponentModel.CancelEventArgs) _ Handles txtQuantity.Validating ' Tests that the textbox is not empty If txtQuantity.Text = "" Then ErrorProvider1.SetError(txtQuantity, _  "Please enter a quantity") e.Cancel = True ' Tests that there are no other errors on the textbox. ElseIf ErrorProvider1.GetError(txtQuantity) <> "" Then e.Cancel = True Else ErrorProvider1.SetError(txtQuantity, "") End If End Sub

6. Press F5 to build and test your code.

To create validation handlers with Visual C#

1. In the Toolbox, double-click the ErrorProvider component. An ErrorProvider is added to the component tray in the designer.

2. In the designer, select txtQuantity. In the Properties window, press the Events button. Double-click the entry for KeyPress. An empty event handler for txtQuantity_KeyPress appears in the code editor.

3. Write code that will display an error if non-numeric characters are entered into the text box.

   Visual C#

   private void txtQuantity_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e) { if (Char.IsDigit(e.KeyChar) == false) errorProvider1.SetError(txtQuantity,  "Please enter a numeric value"); else errorProvider1.SetError(txtQuantity, ""); }

4. In the Solution Explorer, right-click frmMain and choose View Designer. Select txtQuantity. In the Properties window, press the Events button and double-click the entry for Validating. An empty event handler is added to the code editor.

5. Add code to validate that the txtQuantity field is not empty and has no other errors on it. For example:

   Visual C#

   private void txtQuantity_Validating(object sender, System.ComponentModel.CancelEventArgs e) { // Tests that the textbox is not empty if (txtQuantity.Text == "") { errorProvider1.SetError(txtQuantity,  "Please enter a quantity"); e.Cancel = true; } // Tests that there are no other errors on the textbox. else if (errorProvider1.GetError(txtQuantity) != "") e.Cancel = true; else errorProvider1.SetError(txtQuantity, ""); } 

6. Press F5 to build and test your code.