'This code segment implements the IContainer interface. The code segment
'containing the implementation of ISite and IComponent can be found in the documentation
'for those interfaces.
'Implement the LibraryContainer using the IContainer interface.
Class LibraryContainer
Implements IContainer
Private m_bookList As ArrayList
Public Sub New()
m_bookList = New ArrayList()
End Sub
Public Sub Add(ByVal book As IComponent) Implements IContainer.Add
'The book will be added without creation of the ISite object.
m_bookList.Add(book)
End Sub
Public Sub Add(ByVal book As IComponent, ByVal ISNDNNum As String) Implements IContainer.Add
Dim i As Integer
Dim curObj As IComponent
For i = 0 To m_bookList.Count - 1
curObj = CType(m_bookList(i), IComponent)
If curObj.Site IsNot Nothing Then
If (curObj.Site.Name.Equals(ISNDNNum)) Then
Throw New SystemException("The ISBN number already exists in the container")
End If
End If
Next i
Dim data As ISBNSite = New ISBNSite(Me, book)
data.Name = ISNDNNum
book.Site = data
m_bookList.Add(book)
End Sub
Public Sub Remove(ByVal book As IComponent) Implements IContainer.Remove
Dim i As Integer
Dim curComp As BookComponent = CType(book, BookComponent)
For i = 0 To m_bookList.Count - 1
If (curComp.Equals(m_bookList(i)) = True) Then
m_bookList.RemoveAt(i)
Exit For
End If
Next i
End Sub
Public ReadOnly Property Components() As ComponentCollection Implements IContainer.Components
Get
Dim datalist(m_bookList.Count - 1) As IComponent
m_bookList.CopyTo(datalist)
Return New ComponentCollection(datalist)
End Get
End Property
Public Overridable Sub Dispose() Implements IDisposable.Dispose
Dim i As Integer
For i = 0 To m_bookList.Count - 1
Dim curObj As IComponent = CType(m_bookList(i), IComponent)
curObj.Dispose()
Next i
m_bookList.Clear()
End Sub
Public Shared Sub Main()
Dim cntrExmpl As LibraryContainer = New LibraryContainer()
Try
Dim book1 As BookComponent = New BookComponent("Wizard's First Rule", "Terry Gooodkind")
cntrExmpl.Add(book1, "0812548051")
Dim book2 As BookComponent = New BookComponent("Stone of Tears", "Terry Gooodkind")
cntrExmpl.Add(book2, "0812548094")
Dim book3 As BookComponent = New BookComponent("Blood of the Fold", "Terry Gooodkind")
cntrExmpl.Add(book3, "0812551478")
Dim book4 As BookComponent = New BookComponent("The Soul of the Fire", "Terry Gooodkind")
'This will generate an exception, because the ISBN already exists in the container.
cntrExmpl.Add(book4, "0812551478")
Catch e As SystemException
Console.WriteLine("Error description: " + e.Message)
End Try
Dim datalist As ComponentCollection = cntrExmpl.Components
Dim denum As IEnumerator = datalist.GetEnumerator()
While (denum.MoveNext())
Dim cmp As BookComponent = CType(denum.Current, BookComponent)
Console.WriteLine("Book Title: " + cmp.Title)
Console.WriteLine("Book Author: " + cmp.Author)
Console.WriteLine("Book ISBN: " + cmp.Site.Name)
End While
End Sub
End Class