Object-Oriented Programming (OOP) for Beginners

What is OOP?

Object-Oriented Programming (OOP) is a programming style that uses objects to structure code. These objects contain data (properties) and actions (methods).

Why Use OOP?

Four Main OOP Concepts

1. Encapsulation

Hiding details and bundling data with the methods that work on that data.

2. Inheritance

Allows one class to use the properties and methods of another class.

3. Polymorphism

Methods can behave differently depending on the object that calls them.

4. Abstraction

Shows only important features while hiding unnecessary details.

Simple Example (JavaScript)

// Creating a class
class Animal {
  constructor(name) {
    this.name = name; // property
  }

  speak() { // method
    console.log(this.name + " makes a sound.");
  }
}

// Creating an object from the class
const dog = new Animal("Buddy");
dog.speak(); // Output: Buddy makes a sound.

Run Example

You can run the JavaScript example below:



    

    
VB.NET Examples

    

      
' Creating a class
Public Class Animal
    Public Property Name As String

    Public Sub New(name As String)
        Me.Name = name
    End Sub

    Public Overridable Sub Speak()
        Console.WriteLine(Name & " makes a sound.")
    End Sub
End Class

' Inheritance example
Public Class Dog
    Inherits Animal

    Public Sub New(name As String)
        MyBase.New(name)
    End Sub

    Public Overrides Sub Speak()
        Console.WriteLine(Name & " barks.")
    End Sub
End Class

' Using the classes
Dim pet As New Dog("Buddy")
pet.Speak() ' Output: Buddy barks.
      

    


    
Run Example (Simulation)

    
VB.NET cannot run directly in a webpage, but this button simulates the expected output:

    
    


    

    
More VB.NET Examples


    
Encapsulation Example

    
Public Class BankAccount
    Private balance As Decimal

    Public Sub Deposit(amount As Decimal)
        If amount > 0 Then
            balance += amount
        End If
    End Sub

    Public Function GetBalance() As Decimal
        Return balance
    End Function
End Class

Dim acct As New BankAccount()
acct.Deposit(100)
Console.WriteLine(acct.GetBalance()) ' Output: 100
    


    
Polymorphism Example

    
Public Class Shape
    Public Overridable Function Area() As Double
        Return 0
    End Function
End Class

Public Class Circle
    Inherits Shape

    Public Property Radius As Double

    Public Sub New(r As Double)
        Radius = r
    End Sub

    Public Overrides Function Area() As Double
        Return Math.PI * Radius * Radius
    End Function
End Class

Dim c As New Circle(5)
Console.WriteLine(c.Area()) ' Output: 78.5398...
    


    
Interface Example

    
Public Interface IVehicle
    Sub Drive()
End Interface

Public Class Car
    Implements IVehicle

    Public Sub Drive() Implements IVehicle.Drive
        Console.WriteLine("The car is driving.")
    End Sub
End Class

Dim v As IVehicle = New Car()
v.Drive() ' Output: The car is driving.
    


    
Abstract Class Example

    
Public MustInherit Class Employee
    Public Property Name As String
    Public MustOverride Function Pay() As Decimal
End Class

Public Class HourlyEmployee
    Inherits Employee

    Public Property Hours As Integer
    Public Property Rate As Decimal

    Public Overrides Function Pay() As Decimal
        Return Hours * Rate
    End Function
End Class

Dim worker As New HourlyEmployee() With {.Name="Sam", .Hours=40, .Rate=20}
Console.WriteLine(worker.Pay()) ' Output: 800
    



Conclusion

    

      OOP is a powerful way to organize and manage code. Mastering it will help you write cleaner, more effective programs.
    

    

    
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