Use Overridable Function
Imports System
Public Class MainClass
Shared Sub Main(ByVal args As String())
' instantiate object of class Cylinder
Dim cylinder As New Cylinder(12, 23, 2.5, 5.7)
' properties get initial x-y coordinate, radius and height
Console.WriteLine( "X coordinate is " & cylinder.X & vbCrLf & _
"Y coordinate is " & cylinder.Y & vbCrLf & "Radius is " & _
cylinder.Radius & vbCrLf & "Height is " & cylinder.Height )
' properties set new x-y coordinate, radius and height
cylinder.X = 2
cylinder.Y = 2
cylinder.Height = 10
cylinder.Radius = 4.25
' get new x-y coordinate and radius
Console.WriteLine( "The new location, radius " & _
"and height of cylinder are" & vbCrLf & "Center = [" & _
cylinder.ToString() )
' display Cylinder's diameter
Console.WriteLine( "Diameter is " & _
String.Format("{0:F}", cylinder.Diameter()) )
' display Cylinder's circumference
Console.WriteLine( "Circumference is " & _
String.Format("{0:F}", cylinder.Circumference()) )
' display Cylinder's area
Console.WriteLine("Area is " & _
String.Format("{0:F}", cylinder.Area()) )
' display Cylinder's volume
Console.WriteLine( "Volume is " & _
String.Format("{0:F}", cylinder.Volume()) )
End Sub
End Class
Public Class Cylinder
Inherits Circle
Private mHeight As Double
' default constructor
Public Sub New()
Height = 0
End Sub ' New
' four-argument constructor
Public Sub New(ByVal xValue As Integer, _
ByVal yValue As Integer, ByVal radiusValue As Double, _
ByVal heightValue As Double)
' explicit call to Circle constructor
MyBase.New(xValue, yValue, radiusValue)
Height = heightValue ' set Cylinder height
End Sub ' New
' property Height
Public Property Height() As Double
Get
Return mHeight
End Get
' set Cylinder height if argument value is positive
Set(ByVal heightValue As Double)
If heightValue >= 0 Then
mHeight = heightValue
End If
End Set
End Property ' Height
' override method Area to calculate Cylinder area
Public Overrides Function Area() As Double
Return 2 * MyBase.Area + MyBase.Circumference * mHeight
End Function ' Area
' calculate Cylinder volume
Public Function Volume() As Double
Return MyBase.Area * mHeight
End Function ' Volume
' convert Cylinder to String
Public Overrides Function ToString() As String
Return MyBase.ToString() & "; Height = " & mHeight
End Function ' ToString
End Class
Public Class Circle
Inherits Point ' Circle Inherits from class Point
Private mRadius As Double
' default constructor
Public Sub New()
' implicit call to Point constructor occurs here
Radius = 0
End Sub ' New
' constructor
Public Sub New(ByVal xValue As Integer, _
ByVal yValue As Integer, ByVal radiusValue As Double)
' use MyBase reference to Point constructor explicitly
MyBase.New(xValue, yValue)
Radius = radiusValue
End Sub ' New
' property Radius
Public Property Radius() As Double
Get
Return mRadius
End Get
Set(ByVal radiusValue As Double)
If radiusValue > 0 Then
mRadius = radiusValue
End If
End Set
End Property ' Radius
' calculate Circle diameter
Public Function Diameter() As Double
Return mRadius * 2
End Function ' Diameter
' calculate Circle circumference
Public Function Circumference() As Double
Return Math.PI * Diameter()
End Function ' Circumference
' calculate Circle area
Public Overridable Function Area() As Double
Return Math.PI * mRadius ^ 2
End Function ' Area
' return String representation of Circle
Public Overrides Function ToString() As String
' use MyBase reference to return Point String representation
Return "Center = " & MyBase.ToString() & _
"; Radius = " & mRadius
End Function ' ToString
End Class
Public Class Point
' implicitly Inherits Object
' point coordinate
Private mX, mY As Integer
' default constructor
Public Sub New()
' implicit call to Object constructor occurs here
X = 0
Y = 0
End Sub ' New
' constructor
Public Sub New(ByVal xValue As Integer, _
ByVal yValue As Integer)
' implicit call to Object constructor occurs here
X = xValue
Y = yValue
End Sub ' New
' property X
Public Property X() As Integer
Get
Return mX
End Get
Set(ByVal value As Integer)
mX = value
End Set
End Property ' X
' property Y
Public Property Y() As Integer
Get
Return mY
End Get
Set(ByVal value As Integer)
mY = value
End Set
End Property ' Y
' return String representation of Point
Public Overrides Function ToString() As String
Return "[" & mX & ", " & mY & "]"
End Function ' ToString
End Class
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