vb .net tutorial - 2

Creating Windows Forms

©NIIT Creating Windows Forms/Lesson 2/Slide 1 of 30

Objectives

In this lesson, you will learn to:

Identify the features of Windows Forms

Identify various language features required to work with Windows Forms

Identify various Windows Forms controls

Create Windows Forms



Understanding the User Interface

A user interface is the means by which a user interacts with an application. A well-designed user interface is an effective means of making an application user-friendly.

Types of User Interfaces

Character user interface (CUI)

Graphical user interface (GUI)



Windows Form

Is a representation of any window displayed in an application.

Is used to accept input from a user and display information.



Windows Forms (Contd.)

Windows Form properties:

Are used to determine the appearance of a Windows Form at run time.

Some commonly used properties are:

Name

BackColor

BackgroundImage

Font

Size

StartPosition

Text

WindowState




Windows Forms events:

Click

Closed

Deactivate

Load

MouseMove

MouseDown

MouseUp




Windows Forms methods:

Show()

Activate()

Close()

SetDesktopLocation()



Visual Basic.NET Language Features

Data types:

Byte

Short

Integer

Long

Single

Double

Decimal

Boolean



Visual Basic.NET Language Features (Contd.)

Data types: (Contd.)

Char

String

Date

Object



Visual Basic .NET Language Features (Contd.)

Variables

Allow you to store data.

Have a data type and a name.

Can be declared by using the Dim statement.

Arrays

Are collections of values of the same data type.

Contain elements that can be accessed using a single name and an index number representing the position of the element within the array.




Are declared using the following syntax:

Dim arrayname(Number-of-elements) as datatype

Can be resized using the Redim statement.

Operators

Are used to process the data entered by a user.

Can be categorized as follows:

Arithmetic operators such as +, -, *, /, \, and Mod

Comparison operators such as =, <, >, <=, >=, and <>

Logical operators such as And, Or, Not, and Xor

Concatenation operators such as & and +




Control flow constructs

Decision structures

If-then-else

Select case

Loop structures

While-End while

Do-Loop

For-Next

Nested control statements



Just a Minute…

1. Write a loop structure to display all odd numbers between 1 and 100.

2. Write the construct to check whether the character stored in the variable X is a vowel and display an appropriate message.



Problem Statement 2.D.1

For the Call Center application, a startup screen needs to be provided to accept the user name and password. The application should allow the user to enter the user name and password for a maximum of three times. If in all of the three attempts, a wrong user name and password is entered, the application should display an error and close.



Task List

Identify the variables required to store the values in the application.

Identify the controls to be used for accepting input from the user.

Identify the mechanism to validate the user input.

Create a Windows Form.

Add controls to the Windows Form.

Write the code to validate the user input.

Execute the application.



Task 1: Identify the variables required to store the values in the application.

Result:

The variables required for accepting the login details from a user are:

Counter

Login Name

Password



Task 2: Identify the controls to be used for accepting input from the user.

Visual Basic .NET provides a number of controls that can be added to a form:

TextBox

Is used to display text to a user or accept input from a user.

Has the following properties:

Text

Multiline

Passwordchar



Task 2: Identify the controls to be used for accepting input from the user. (Contd.)

Label

Is used to provide information or description of another control on the Windows Form.

Has the following properties: Text AutoSize




LinkLabelIs used to display the text as a link. Has the following properties:

LinkColor ActiveLinkColor DisabledLinkColor LinkVisited




ListBox

Is used to display a list of items to a user.

Can be populated by using the Add() method of the Items collection.


SelectionMode

Sorted

SelectedIndex

SelectedItem




ComboBox

Is used to display a drop-down list of items.

Can be populated by using the Add() method of the Items collection.


Text

Sorted

SelectedIndex

SelectedItem




CheckBox

Is used to set Yes/No or True/false options.


Text

Checked




RadioButton

Is used to provide a set of mutually exclusive options to the user.


Text

Checked




GroupBox

Is used to group related controls.

Button

Is used to perform an action when a user clicks it.

Has the Text property, which is used to set the text displayed on the button.

StatusBar

Is used to display the status information.


ShowPanels

Text




Some common properties found in most of the controls are:

Name

Visible

Location

Enabled




Some common events found in most of the controls are:

KeyDown KeyUp KeyPress MouseDown MouseUp MouseMove ReSize VisibleChanged




Result:

You will use the following controls for the given problem statement:

Label

TextBox

Button



Task 3: Identify the mechanism to validate the user input.

Result:

The program should use the If-Then construct to validate the user name and the password. The If‑Then construct can also be used to ensure that value of the counter is not greater than 3.



Task 4: Create a Windows Form.

Task 5: Add controls to the Windows Form.

Task 6: Write the code to validate the user input.

Task 7: Execute the application.



Just a Minute…

You have created two forms named Form1 and Form2. Write the code so that when a user clicks the OK button in Form1, Form2 should be displayed.



Problem Statement 2.P.1

Diaz Telecommunications needs an application to accept order details. The details to be accepted include order number, date, customer ID, product ID, cost, and advance. The product IDs should be displayed in a combo box. When a user clicks the Save button after entering order details, the application should verify that none of the fields is left blank and display an appropriate message.



Summary

In this lesson, you learned that:

A form is used to accept input from the user and present information to the user.

An event gets generated on performing an action such as clicking the mouse or pressing a key from the keyboard.

When an event is raised, the code within the event handler is executed.

Variables are used to store data at run time. You can declare a variable by using the Dim statement.

The decision structures supported by Visual Basic .NET include: If-Then-Else

Select-Case



Summary (Contd.)

The loop structures supported by Visual Basic .NET are:

While-End While

Do-Loop

For-Next

Controls can be added to a form to accept input from the user or display some information on the form.

Some commonly used controls are TextBox, Label, CheckBox, RadioButton, and Button.

vb .net tutorial - 2

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