UGC Net Answer Key December 2014

Visual Basic .Net Window Programming

Horizontal and Vertical Scroll Bar,Numeric Scroll Bar,Progress Bar and Domain Name Scroll Bar Demo

Public Class Form1

    Dim i As Integer

    Private Sub VScrollBar1_Scroll_1(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ScrollEventArgs) Handles VScrollBar1.Scroll

        lblR.Text = VScrollBar1.Value

        Me.BackColor = Color.FromArgb(VScrollBar1.Value, VScrollBar2.Value, VScrollBar3.Value)

    End Sub

C# Window Programming

Combo Box

A combo box is a commonly used graphical user interface widget (or control). Traditionally, it is a combination of a drop-down list or list box and a single-line editable textbox, allowing the user to either type a value directly or select a value from the list. The term "combo box" is sometimes used to mean "drop-down list". In both Java and .NET, "combo box" is not a synonym for "drop-down list". Definition of "drop down list" is sometimes clarified with terms such as "non-editable combo box" (or something similar) to distinguish it from "combo box".

C# Basic Concept and Tutorial

Static Classes

A class can be declared static, which indicates that it contains only static members. It is not possible to use the new keyword to create instances of a static class. Static classes are loaded automatically by the .NET Framework common language runtime (CLR) when the program or namespace that contains the class is loaded.

Use a static class to contain methods that are not associated with a particular object. For example, it is a common requirement to create a set of methods that do not act on instance data and are not associated to a specific object in your code. You could use a static class to hold those methods.

Following are the main features of a static class:

·         They only contain static members.

·         They cannot be instantiated.

·         They are sealed.

·         They cannot contain Instance Constructors (C# Programming Guide).

Creating a static class is therefore basically the same as creating a class that contains only static members and a private constructor. A private constructor prevents the class from being instantiated.

The advantage of using a static class is that the compiler can check to make sure that no instance members are accidentally added. The compiler will guarantee that instances of this class cannot be created.

Static classes are sealed and therefore cannot be inherited. They cannot inherit from any class except Object. Static classes cannot contain an instance constructor; however, they can have a static constructor. For more information

Static Members

A static method, field, property, or event is callable on a class even when no instance of the class has been created. If any instances of the class are created, they cannot be used to access the static member. Only one copy of static fields and events exists, and static methods and properties can only access static fields and static events. Static members are often used to represent data or calculations that do not change in response to object state; for example, a math library might contain static methods for calculating sine and cosine.

Static methods can be overloaded but not overridden.

Static class members are declared by using the static keyword before the return type of the member, for example: