Module Module11
    Sub Main()
        Dim c As Child
        c = New Child
        c.P1()
        c.C1()
        Console.ReadLine ()
    End Sub
End Module
Public Class Parent
    Public Sub P1()
        Console.WriteLine ("Parent P1")
    End Sub
End Class
Public Class Child: Inherits Parent
    Public Sub C1()
        Console.WriteLine ("Child C1")
    End Sub
End Class

Module Module12
    Sub Main()
        Dim obj As New SubClass
        obj.DoSomething()
        Console.ReadLine()
    End Sub
End Module
Public Class Parent
    Public Overridable Sub DoSomething()
        Console.WriteLine("Hello from Parent")
    End Sub
End Class
Public Class SubClass
    Inherits Parent
    Public Overrides Sub DoSomething()
        Console.WriteLine("Hello from SubClass")
    End Sub
End Class

Module Module3
    Public Sub Main()
        Dim counter As Calculator
        counter = New Calculator
        ' pass two integers
        Console.WriteLine(counter.Add(1, 5))
        ' pass two doubles
        Console.WriteLine(counter.Add(1.3, 5.9))
        Console.ReadLine()
    End Sub
End Module

Class Calculator
    Public Overloads Function Add(ByVal a As Integer, ByVal b As Integer) As Integer
        Add = a + b
    End Function
    Public Overloads Function Add(ByVal a As Double, ByVal b As Double) As Double
        Add = a + b
    End Function
End Class

Module Module4
    Sub Main()
        Dim mc1 As New MyClass1
        Dim mc2 As New MyClass2
        mc1.Method1()
        mc2.Method1()
        mc2.Method2(10)
        mc2.Method2("Saravanan")
        Console.ReadLine()
    End Sub 'Main
End Module

Class MyClass1
        Public Overridable Sub Method1()
            Console.WriteLine("Method #1")
        End Sub
End Class 'MyClass1

Class MyClass2
        Inherits MyClass1
        Public Overloads Sub Method1()
            Console.WriteLine("Overloading No Argument")
        End Sub
        Public Overloads Sub Method2(ByVal i As Integer)
            Console.WriteLine("Overloading Integer Argument")
        End Sub
        Public Overloads Sub Method2(ByVal s As String)
            Console.WriteLine("Overloading String Argument")
        End Sub
End Class 'MyClass2

Module Module5
    Sub Main()
        Dim employee As Employee
        employee = New Manager
        employee.Work()
        employee = New Employee
        employee.Work()
        Dim manage As Manager
        manage = New Manager
        manage.Manage()
        manage.Work()
        Console.ReadLine()
    End Sub
End Module

Class Employee
    Public Overridable Sub Work()
        System.Console.WriteLine("I am an employee.")
    End Sub
End Class

Class Manager : Inherits Employee
    Public Sub Manage()
        System.Console.WriteLine("Managing ...")
    End Sub
    Public Overrides Sub Work()
        System.Console.WriteLine("I am a manager")
    End Sub
End Class

Module Module6
    Sub Main()
        Dim mc As New MyClass2
        mc.AbMethod1()
        mc.AbMethod2()
        Console.ReadLine()
    End Sub 'Main
End Module

MustInherit Class MyAbs
    Public MustOverride Sub AbMethod1()
    Public MustOverride Sub AbMethod2()
End Class 'MyAbs

'not necessary to implement all abstract methods partial implementation is possible
MustInherit Class MyClass1
    Inherits MyAbs
    Public Overrides Sub AbMethod1()
        Console.WriteLine("Abstarct method #1")
    End Sub 'AbMethod1
End Class 'MyClass1

Class MyClass2
    Inherits MyClass1
    Public Overrides Sub AbMethod2()
        Console.WriteLine("Abstarct method #2")
    End Sub 'AbMethod2
End Class 'MyClass2

Module Module7
    Sub Main()
        Dim mc As New MyClass1
        mc.AbMethod1()
        mc.AbMethod2()
        Console.ReadLine()
    End Sub 'Main
End Module

MustInherit Class MyAbs
    Public MustOverride Sub AbMethod1()
    Public MustOverride Sub AbMethod2()
End Class 'MyAbs

Class MyClass1
    Inherits MyAbs
    Public Overrides Sub AbMethod1()
        Console.WriteLine("Abstarct method #1 of MyClass1")
    End Sub 'AbMethod1
    Public Overrides Sub AbMethod2()
        Console.WriteLine("Abstarct method #2 of MyClass1")
    End Sub 'AbMethod2
End Class 'MyClass1

Module Module8
    Sub Main()
        Dim a As New A
        a.AbMethod()
        a.AA()
        a.NonAbMethod()
        Dim c As New C
        c.CC()
        Dim d As New D
        d.AbMethod()
        d.NonAbMethod()
        d.AA()
        Console.ReadLine()
    End Sub
End Module


Public Class A
    Inherits B
    Public Sub New()
        Console.WriteLine("Class A Constructor!")
    End Sub
    'Overriding refers to the methods in the child class having the same signature (name as well as ‘parameters) as of the parent class methods.

    Public Overrides Sub AbMethod()
        Console.WriteLine("Abstarct Method!")
    End Sub
    Public Overridable Sub AA()
        Console.WriteLine("Class A Overridable AA!")
    End Sub
End Class

Public MustInherit Class B
    'Note : MustInherit means that the class cannot be instantiated 
    '(DerivedObjAs New BaseObj) but rather must be inherited. 
    Public Sub New()
        Console.WriteLine("Abstract Class!")
    End Sub
    Public MustOverride Sub AbMethod()    ' An abstract method
    Public Sub NonAbMethod()              ' NonAbMethod
        Console.WriteLine("Non-Abstract Method")
    End Sub
End Class

Public NotInheritable Class C
    'Note : NotInheritable means that the class cannot be inherited 
    '(DerivedObjInherits BaseObj) but rather must be instantiated. 
    Public Sub New()
        Console.WriteLine("Class C Constructor!")
    End Sub
    Public Sub CC()
        Console.WriteLine("Class C Method CC")
    End Sub
End Class

Public Class D
    Inherits A
    Public Overrides Sub AA()
        Console.WriteLine("Overriding AA!")
    End Sub
End Class

Module Module9
    Sub Main()
        Dim obj As New Calculator
        Console.WriteLine("Add      (567+234) :" & obj.Add(567, 234))
        Console.WriteLine("Substract(567-234) :" & obj.Subtract(567, 234))
        Console.ReadLine()
    End Sub 'Main
End Module

Public Interface IAdd
    Function Execute(ByVal i As Integer, ByVal j As Integer) As Integer
End Interface

Public Interface ISubtract
    Function Execute(ByVal i As Integer, ByVal j As Integer) As Integer
End Interface

Public Class Calculator
    Implements IAdd, ISubtract
    Public Function Add(ByVal i As Integer, ByVal j As Integer) As Integer Implements IAdd.Execute
        Return i + j
    End Function
    Public Function Subtract(ByVal i As Integer, ByVal j As Integer) As Integer Implements ISubtract.Execute
        Return i - j
    End Function
End Class

Module Module10
    Sub Main()
        Dim mc As New MyClass1
        mc.Method()
        Console.ReadLine()
    End Sub 'Main
End Module
Public Class MyAbs
    Public Sub Method()
        Console.WriteLine("Method")
    End Sub
End Class 'MyAbs

Class MyClass1
    Inherits MyAbs
    Public Shadows Sub Method()
        Console.WriteLine("Shadow Method")
    End Sub
End Class 'MyClass1

Module Module11
    Sub Main()
        Dim mc1 As New MyClass1
        mc1.Method()
        Console.ReadLine()
    End Sub 'Main
End Module

Public Class MyAbs
    Protected Class MyClass2
        Public Shared Name As String = "MyAbs - NestedClass"
    End Class

    Public Sub Method()
        Console.WriteLine(MyClass2.Name)
    End Sub
End Class 'MyAbs

Public Class MyClass1
    Inherits MyAbs
    Protected Shadows Class MyClass2
        Public Shared Name As String = "MyClass1 - NestedClass"
    End Class
    Public Shadows Sub Method()
        Console.WriteLine(MyClass2.Name)
    End Sub
End Class 'MyClass1

Module Module12
    Sub Main()
        Dim p As Parent
        Dim c As Child
        p = New Parent
        p.P1()
        p.P2()
        p = New Child
        p.P1()
        Console.ReadLine()
    End Sub
End Module

Public Class Parent
    Public Overridable Sub P1()
        Console.WriteLine("Parent P1")
    End Sub
    Public Sub P2()
        MyClass.P1()
        'Implementing keyword MyClass here tells all derived classes to refer to the 
        'base / abstract class wherein the keyword MyClass appears
    End Sub
End Class

Public Class Child : Inherits Parent
    Public Overrides Sub P1()
        Console.WriteLine("Child P1")
        MyBase.P2()
    End Sub
End Class

Module Module13
    Sub Main()
        Dim ball As Sphere = New Sphere
        ball.ShowCharacteristics()
        Console.ReadLine()
    End Sub
End Module
Public Class Circle
    Public Radius As Double
    Public Function CalculateDiameter() As Double
        Return Radius * 2
    End Function
    Public Function CalculateCircumference() As Double
        Return CalculateDiameter() * 3.14159
    End Function
End Class

Public Class Sphere
    Inherits Circle
    Public Sub ShowCharacteristics()
        Me.Radius = 35.84
        Console.WriteLine("Circle Characteristics")
        Console.WriteLine("===================================")
        Console.WriteLine("Radius:        {0}", Me.Radius)
        Console.WriteLine("Diameter:      {0}", Me.CalculateDiameter())
        Console.WriteLine("Circumference: {0}", Me.CalculateCircumference())
        Console.WriteLine("===================================")
    End Sub
End Class