' Visual Basic 2008 9.0 .NET Examples - Collections - Introduction - Object Oriented Programming : 
Class Rectangle
    Private m_Height As Integer
    Public Property Height() As Integer
        Get
            Height = m_Height
        End Get
        Set(ByVal value As Integer)
            m_Height = value
        End Set
    End Property
    Private m_Width As Integer
    Public Property Width() As Integer
        Get
            Width = m_Width
        End Get
        Set(ByVal value As Integer)
            m_Width = value
        End Set
    End Property
    Public Function GetArea() As Integer
        GetArea = Height * Width
    End Function
End Class
Class Rectangles
    Private m_Items As Rectangle()
    Default Public ReadOnly Property Item(ByVal index As Integer) As Rectangle
        Get
            Item = m_Items(index)
        End Get
    End Property
    Private m_Count As Integer
    Public ReadOnly Property Count() As Integer
        Get
            Count = m_Count
        End Get
    End Property
    Public Sub Add(ByVal rectangle As Rectangle)
        ReDim Preserve m_Items(Count)
        m_Items(Count) = rectangle
        m_Count += 1
    End Sub
    Public Sub RemoveAt(ByVal index As Integer)
        For itemIndex As Integer = index To Count - 2
            m_Items(itemIndex) = m_Items(itemIndex + 1)
        Next
        ReDim Preserve m_Items(Count - 2)
        m_Count -= 1
    End Sub
    Public Function GetTotalArea() As Integer
        For Each item As Rectangle In m_Items
            GetTotalArea += item.GetArea()
        Next
    End Function
End Class
Module Exercise1Solution
    Sub Main()
        Dim rectangle1 As Rectangle = New Rectangle
        rectangle1.Height = 1
        rectangle1.Width = 2
        Console.WriteLine(rectangle1.GetArea())
        '
        Dim rectangle2 As Rectangle = New Rectangle
        rectangle2.Height = 3
        rectangle2.Width = 4
        Console.WriteLine(rectangle2.GetArea())
        '
        Dim rectangles1 As Rectangles = New Rectangles
        rectangles1.Add(rectangle1)
        rectangles1.Add(rectangle2)
        '
        For index As Integer = 0 To rectangles1.Count - 1
            Console.Write(rectangles1(index).GetArea() & " ")
        Next
        Console.WriteLine()
        Console.WriteLine(rectangles1.GetTotalArea())
        '
        rectangles1.RemoveAt(1)
        '
        For index As Integer = 0 To rectangles1.Count - 1
            Console.Write(rectangles1(index).GetArea() & " ")
        Next
        Console.WriteLine()
        Console.WriteLine(rectangles1.GetTotalArea())
        '
        Console.ReadLine()
    End Sub
End Module
' Visit www.studyvb.com for more examples.  Copyright 2003-2008 De Wolf.