Static classes:
There are main features
of a static class-
- One is no object of static class can be created
- A static class must contain only static members
- A static class cannot have an instance constructor, it can have a static constructor.
- Static classes cannot be instantiated.
- Static classes are sealed and therefore cannot be inherited.
Benefit of static class:
We do not need to make any instance of this class, all members
can be accessible with its own name.
Declaration:
A static class is created by using keyword 'Static' as shown
here:
Static class Clasname
{
//C#
}
{
//C#
}
One more thing that is notable-within static class, all members
must be explicitly specified as static, static class does not automatically
make its members static. Static class can contain a collection of static
methods.
Example:
using System;
static class Shape
{
public static double
GetArea(double Width, double height)
{
return Width
* Height;
}
}
class Ractangle
{
private void
GetRactangleArea()
{
Double Area;
Area = Shape.GetArea(10,
5);
}
}
Shape is static class, it contain static function
GetArea.Ractangle is other class and within GetArea function can be access
without creating instance of Class Shape.
Static Method -
Static Method -
The methods in C# may or may not take parameters and they may or may not return a value. Also, a custom method that is also known as a user defined method may be declared non-static (instance level) or static (class level). When a method is static then it can be invoked directly from the class level without creating an object. This is the reason for making a main() function/method static. Another example is the WriteLine() method that is called/used without creating any object. Let's explore further using an example.
class Program
{
public static void withoutObj()
{
Console.WriteLine("Hello");
}
{
Program. withoutObj();
Console.ReadKey();
}
}
{
public static void withoutObj()
{
Console.WriteLine("Hello");
}
{
Program. withoutObj();
Console.ReadKey();
}
}
In the above example, I will be calling a method using the class name itself without an object being used for the WriteLine().
Using Static Method
Usually we define a set of data members for a class and then every object of that class will have a separate copy of each of those data members. Let's have an example.
class Program
{
public int myVar; //a non-static field
{
Program p1 = new Program(); //a object of class
p1.myVar = 10;
Console.WriteLine(p1.myVar);
Console.ReadKey();
}
}
{
public int myVar; //a non-static field
{
Program p1 = new Program(); //a object of class
p1.myVar = 10;
Console.WriteLine(p1.myVar);
Console.ReadKey();
}
}
In the above example, myVar is a non-static field so to use this field we first need to create the object of that class. On the other hand, static data is shared among all the objects of that class. That is, for all the objects of a class, there will be only one copy of static data. Let's have an example.
class Program
{
public static int myVar; //a static field
{
//Program p1 = new Program(); //a object of class
myVar = 10;
Console.WriteLine(myVar);
Console.ReadKey();
}
}
{
public static int myVar; //a static field
{
//Program p1 = new Program(); //a object of class
myVar = 10;
Console.WriteLine(myVar);
Console.ReadKey();
}
}
In the above we don't have an object of the class to use that field since the field is static.
Notable Points here are:
1. A static method can be invoked directly from the class level
2. A static method not requires any class object
3. Any main() method is shared through entire class scope so it always appears with static keyword.
