OOPS
Concepts
Class
Object
Encapsulation
Abstraction
Inheritance
Polymorphism
Class
It
is a collection of objects. Or it is the blueprint design.
Example:
Let’s take our home
Home
is our Class
Kitchen,
bedroom, hall is our method
Kitchen,
bedroom and hall contain its own properties.
Kitchen
has set of dishes, gas etc.
Bedroom
has bed, table lamp, television etc.
Hall
have sofa, dining table etc.
public class Home
{
#region Kitchen
Properties
public int setOfDishes
= 0;
public int noOfGasCylinder
= 0;
#endregion
#region Bedroom
Properties
public int noOfBed
= 0;
public int noOfTableLamp
= 0;
public int noOfTelevision
= 0;
#endregion
#region Hall
Properties
public int noOfSofa
= 0;
public int noOfDiningTable
= 0;
public int noOfChair
= 0;
#endregion
public void Kitchen()
{
setOfDishes = 10;
noOfGasCylinder = 2;
Console.WriteLine("Set
Of Dishes = {0}", setOfDishes);
Console.WriteLine("No
Of Gas Cylinder = {0}", noOfGasCylinder);
}
public void Bedroom()
{
noOfBed = 1;
noOfTableLamp = 1;
noOfTelevision = 1;
Console.WriteLine("No
Of Bed = {0}", noOfBed);
Console.WriteLine("No
Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("No
Of Television = {0}", noOfTelevision);
}
public void Hall()
{
noOfSofa = 2;
noOfDiningTable = 1;
noOfChair = 6;
Console.WriteLine("No
Of Sofa = {0}", noOfSofa);
Console.WriteLine("No
Of Dining Table = {0}", noOfDiningTable);
Console.WriteLine("No
Of Chair = {0}", noOfChair);
}
}
Object
Object
is an instance of a class.
Instances
of classes are created by using the new operator.
Now
we want to access the Kitchen method
of Home class
So,
we can create the Instances of home class to access the Kitchen method
Home objHome = new Home();
objHome.Kitchen();
Encapsulation
In
our house example, I have already told that House security guard limitation is
the entrance of the house. The security guard doesn’t need to know about what
is happening inside the house. Therefore, the House Owner will hide from the
Security guard all the happenings for more safety for his safety. The hiding
and limitation are called as Encapsulation.
For
example, we have two Classes the first one is “Home” class and the other class
as “HomeSecurity” class Here we can see all the variables are wrap into a class
where “HomeSecurity” class is set as public, so the “Home” class can access
that, but “Home” class has both Public and private variable where the private
variable of a class cannot be accessed outside of the class.
public class HomeSecurity
{
public int NoOfSecurity;
public string SecurityName
= string.Empty;
}
public class Home
{
private int NoOfLockerInHosue
= 2;
public string OwnerName
= string.Empty;
}
Abstraction
1. Abstraction
is to show and share some common information to the user.
2. Let’s
take our House example, in our house we will have servant, servants can go to
all rooms and do cleaning and other works.
3. The
house owner can give full rights or some partial rights to the servant for
accessing his house.
4. How
to abstract: - By using Access modifiers
There
are 5 different access modifiers in c#.
1.
Private
2.
Protected
3.
Internal
4.
Protected Internal
5.
Public
Private
- Only with in containing class
Protected
- With the containing class and the class derived from the containing
class
Internal
- Anywhere within the containing assembly
Protected
Internal - Anywhere within the containing assembly, and from
within a derived class in any
another
assembly
Public
- Anywhere
Inheritance
1. In
simple word Inheritance means something we got from our ancestor.
2. Inheritance
is nothing but accessing and using all base class variable and methods in the
Derived Class.
3. The
class whose members are inherited is called the base class, and the class that
inherits those members is called the derived class.
public class Home
{
public Home()
{
Console.WriteLine("Home
class constructor");
}
public virtual void Kitchen(int setOfDishes, int noOfGasCylinder)
{
Console.WriteLine("Home
- Set Of Dishes = {0}", setOfDishes);
Console.WriteLine("Home
- No Of Gas Cylinder = {0}", noOfGasCylinder);
}
public virtual void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision)
{
Console.WriteLine("Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Home
- No Of Television = {0}", noOfTelevision);
}
public virtual void Hall(int noOfSofa, int noOfDiningTable, int noOfChair)
{
Console.WriteLine("Home
- No Of Sofa = {0}", noOfSofa);
Console.WriteLine("Home
- No Of Dining Table = {0}", noOfDiningTable);
Console.WriteLine("Home
- No Of Chair = {0}", noOfChair);
}
public virtual void RentedHome()
{
Console.WriteLine("Home
is not Rented Home.");
}
}
public class Ram_Home : Home
{
public Ram_Home()
{
Console.WriteLine("Ram_Home
class constructor");
}
public override void Kitchen(int setOfDishes, int noOfGasCylinder)
{
Console.WriteLine("Ram_Home
- Set Of Dishes = {0}", setOfDishes);
Console.WriteLine("Ram_Home
- No Of Gas Cylinder = {0}", noOfGasCylinder);
}
public override void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision)
{
Console.WriteLine("Ram_Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Ram_Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Ram_Home
- No Of Television = {0}", noOfTelevision);
}
public new void Hall(int noOfSofa, int noOfDiningTable, int noOfChair)
{
Console.WriteLine("Ram_Home
- No Of Sofa = {0}", noOfSofa);
Console.WriteLine("Ram_Home
- No Of Dining Table = {0}", noOfDiningTable);
Console.WriteLine("Ram_Home
- No Of Chair = {0}", noOfChair);
}
}
class Program
{
static void Main(string[] args)
{
Console.WriteLine("-----------------------------Home
class object");
Home objHome
= new Home();
Console.WriteLine("---------------Kitchen");
objHome.Kitchen(10, 2);
Console.WriteLine("---------------Bedroom");
objHome.Bedroom(1, 1, 1);
Console.WriteLine("---------------Hall");
objHome.Hall(1, 1, 6);
Console.WriteLine("---------------RentedHome");
objHome.RentedHome();
Console.WriteLine("-----------------------------Ram_Home
class object");
Ram_Home objRam_Home
= new Ram_Home();
Console.WriteLine("---------------Kitchen");
objRam_Home.Kitchen(20, 1);
Console.WriteLine("---------------Bedroom");
objRam_Home.Bedroom(1, 1, 1);
Console.WriteLine("---------------Hall");
objRam_Home.Hall(2, 1, 4);
Console.WriteLine("---------------RentedHome");
objRam_Home.RentedHome();
Console.WriteLine("-----------------------------Home
class object references an object of Ram_Home");
Home objHome1
= new Ram_Home();
Console.WriteLine("---------------Kitchen");
objHome1.Kitchen(10, 2);
Console.WriteLine("---------------Bedroom");
objHome1.Bedroom(1, 1, 1);
Console.WriteLine("---------------Hall");
objHome1.Hall(1, 1, 6);
Console.WriteLine("---------------RentedHome");
objHome1.RentedHome();
Console.ReadLine();
}
}
Step
1:- Home class object
1. Now
create the object of home class i.e. also called base or parent class.
Home objHome
= new Home();
Console.WriteLine("---------------Kitchen");
objHome.Kitchen(10, 2);
Console.WriteLine("---------------Bedroom");
objHome.Bedroom(1, 1, 1);
Console.WriteLine("---------------Hall");
objHome.Hall(1, 1, 6);
Console.WriteLine("---------------RentedHome");
objHome.RentedHome();
Output
Home
class constructor
---------------Kitchen
Home
- Set Of Dishes = 10
Home
- No Of Gas Cylinder = 2
---------------Bedroom
Home
- No Of Bed = 1
Home
- No Of Table Lamp = 1
Home
- No Of Television = 1
---------------Hall
Home
- No Of Sofa = 1
Home
- No Of Dining Table = 1
Home
- No Of Chair = 6
---------------RentedHome
Home
is not Rented Home.
2. Home
class constructor getting called first and then after it will print all the
method of home class as expected.
Step
2:- Ram_Home class object
1. Now
create the object of Ram_Home class i.e. also called Derived or Child class.
Ram_Home objRam_Home
= new Ram_Home();
Console.WriteLine("---------------Kitchen");
objRam_Home.Kitchen(20, 1);
Console.WriteLine("---------------Bedroom");
objRam_Home.Bedroom(1, 1, 1);
Console.WriteLine("---------------Hall");
objRam_Home.Hall(2, 1, 4);
Console.WriteLine("---------------RentedHome");
objRam_Home.RentedHome();
Output
Home class constructor
Ram_Home
class constructor
---------------Kitchen
Ram_Home
- Set Of Dishes = 20
Ram_Home
- No Of Gas Cylinder = 1
---------------Bedroom
Ram_Home
- No Of Bed = 1
Ram_Home
- No Of Table Lamp = 1
Ram_Home
- No Of Television = 1
---------------Hall
Ram_Home
- No Of Sofa = 2
Ram_Home
- No Of Dining Table = 1
Ram_Home
- No Of Chair = 4
---------------RentedHome
Home is not Rented Home.
2. Base
class constructor getting called first and then derived class constructor
getting called because Ram_Home class Inherited the Home class
3. It
will print all the method of a derived class as expected except Rented_Home()
method because we have not implemented the Rented_Home() method in derived
class.
4. In
Inheritance, when we are creating the object of Derived class it will search
respective method in derived class first and then went to base class.
5. If
any method not present in the derived class, then it will search that method in
the base class and print the base class method.
Step
3:- Home class object references an object of Ram_Home
1. Now
create the object of Home class, but it references an object of Ram_Home class.
Home objHome1 = new Ram_Home();
Console.WriteLine("---------------Kitchen");
objHome1.Kitchen(10, 2);
Console.WriteLine("---------------Bedroom");
objHome1.Bedroom(1, 1, 1);
Console.WriteLine("---------------Hall");
objHome1.Hall(1, 1, 6);
Console.WriteLine("---------------RentedHome");
objHome1.RentedHome();
Output
Home class constructor
Ram_Home
class constructor
---------------Kitchen
Ram_Home
- Set Of Dishes = 10
Ram_Home
- No Of Gas Cylinder = 2
---------------Bedroom
Ram_Home
- No Of Bed = 1
Ram_Home
- No Of Table Lamp = 1
Ram_Home
- No Of Television = 1
---------------Hall
Home - No Of Sofa = 1
Home - No Of Dining Table = 1
Home - No Of Chair = 6
---------------RentedHome
Home is not Rented Home.
2. Base
class constructor getting called first followed by the derived class
constructor.
3. It
will print the Kitchen(), Bedroom() method of a derived class because
Kitchen(), Bedroom() method overridden in derived class.
4. Hall()
method print from base class because we have use new keyword, new keyword
explicitly hides a member or method of derived class that is inherited from a
base class
5. we
have not implemented the Rented_Home() method in derived class so it will called
from base class.
Polymorphism
Using
same method name with different parameter is an example for the polymorphism.
Polymorphisms
have two types:
1. Method
Overloading is also called Compile Time Polymorphism
2. Method Overriding is also called Run time
Polymorphism
Method
Overloading (Compile Time Polymorphism) (Early Binding):
1. Method
Overloading means same method name using more than one method with different
argument in the same class.
public class Home
{
public void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision)
{
Console.WriteLine("Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Home
- No Of Television = {0}", noOfTelevision);
}
public void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision, string WallColour)
{
Console.WriteLine("Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Home
- No Of Television = {0}", noOfTelevision);
Console.WriteLine("Home
- Wall Colour = {0}", WallColour);
}
static void Main(string[] args)
{
Home objHome
= new Home();
objHome.Bedroom(1, 1, 1);
objHome.Bedroom(1, 1, 1, "White");
Console.ReadLine();
}
}
Output
Method
Argument with 3 Parameter
Home
- No Of Bed = 1
Home
- No Of Table Lamp = 1
Home
- No Of Television = 1
Method
Argument with 4 Parameter
Home
- No Of Bed = 1
Home
- No Of Table Lamp = 1
Home
- No Of Television = 1
Home
- Wall Colour = White
Method
Overriding (Run time Polymorphism) (Late Binding):
1. Method
overriding occurs when child class declares a method that has the same type
arguments as a method declared by one of its superclass.
2. Method
overriding can only be used in the derived class.
3. Method
Overriding cannot be done in the same class.
4. Method
Overriding can be used in Abstract Method, Virtual Method and in Sealed Method
Note: By default
functions are not virtual in C# and so you need to write “virtual” explicitly.
What
is Virtual Method:-
By
declaring base class function as virtual, we allow the function to be
overridden in any of derived class.
public class Home
{
public virtual void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision)
{
Console.WriteLine("Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Home
- No Of Television = {0}", noOfTelevision);
}
public virtual void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision, string WallColour)
{
Console.WriteLine("Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Home
- No Of Television = {0}", noOfTelevision);
Console.WriteLine("Home
- Wall Colour = {0}", WallColour);
}
}
public class Ram_Home : Home
{
public override void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision)
{
Console.WriteLine("Ram_Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Ram_Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Ram_Home
- No Of Television = {0}", noOfTelevision);
}
public override void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision, string WallColour)
{
Console.WriteLine("Ram_Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Ram_Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Ram_Home
- No Of Television = {0}", noOfTelevision);
Console.WriteLine("Ram_Home
- Wall Colour = {0}", WallColour);
}
}
class Program
{
static void Main(string[] args)
{
Console.WriteLine("-----------------------------Home
class object references an object of Ram_Home");
Home objHome
= new Ram_Home();
Console.WriteLine("---------------Bedroom()
method with 3 argument");
objHome.Bedroom(1, 1, 1);
Console.WriteLine("---------------Bedroom()
method with 4 argument");
objHome.Bedroom(1, 1, 1, "White");
Console.ReadLine();
}
}
Abstract
class:-
1. The
Abstract class is a special type of class that should be declared with the
abstract keyword.
2. It
should contain one or more abstract methods or not abstract methods, which
should contain only method definitions.
3. It
won't have any method body (in the form of curly braces), so the method
definition is followed by a semicolon instead of a normal method block.
4. An
abstract class cannot be instantiated.
5. The
purpose of an abstract class is to provide a common definition of a base class
that multiple derived classes can share.
6. Derived
classes of the abstract class must implement all abstract methods.
public abstract class Home
{
public abstract void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision);
public abstract void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision, string WallColour);
}
public class Ram_Home : Home
{
public override void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision)
{
Console.WriteLine("Ram_Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Ram_Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Ram_Home
- No Of Television = {0}", noOfTelevision);
}
public override void Bedroom(int noOfBed, int noOfTableLamp, int noOfTelevision, string WallColour)
{
Console.WriteLine("Ram_Home
- No Of Bed = {0}", noOfBed);
Console.WriteLine("Ram_Home
- No Of Table Lamp = {0}", noOfTableLamp);
Console.WriteLine("Ram_Home
- No Of Television = {0}", noOfTelevision);
Console.WriteLine("Ram_Home
- Wall Colour = {0}", WallColour);
}
}
class Program : Ram_Home
{
static void Main(string[] args)
{
Program objHome
= new Program();
Console.WriteLine("---------------Bedroom()
method with 3 argument");
objHome.Bedroom(1, 1, 1);
Console.WriteLine("---------------Bedroom()
method with 4 argument");
objHome.Bedroom(1, 1, 1, "White");
Console.ReadLine();
}
}
