в 16:40, 26 мая 2010

2010-05-26T16:40:30Z

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2010-05-26T12:55:41Z

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==Overrides and Shadows methods from base class==

<source lang="vbnet">Option Strict On
Imports System
Imports Microsoft.VisualBasic
Interface Printable
Sub Read( )
Sub Write( )
End Interface
Public Class Document : Implements Printable
Public Sub New(ByVal s As String)
Console.WriteLine("Creating document with: {0}", s)
End Sub
Public Overridable Sub Read( ) Implements Printable.Read
Console.WriteLine("Document Virtual Read Method for Printable")
End Sub
Public Sub Write( ) Implements Printable.Write
Console.WriteLine("Document Write Method for Printable")
End Sub
End Class
Public Class Note : Inherits Document
Public Sub New(ByVal s As String)
MyBase.New(s)
Console.WriteLine("Creating note with: {0}", s)
End Sub
Public Overrides Sub Read( )
Console.WriteLine("Overriding the Read method for Note!")
End Sub
Public Shadows Sub Write( )
Console.WriteLine("Implementing the Write method for Note!")
End Sub
End Class
Class Tester
Public Shared Sub Main( )
Dim theNote As Document = New Note("Test Note")
If TypeOf theNote Is Printable Then
Dim isNote As Printable = theNote
isNote.Read( )
isNote.Write( )
End If
Console.WriteLine(vbCrLf)
theNote.Read( )
theNote.Write( )
Console.WriteLine(vbCrLf)
Dim note2 As New Note("Second Test")
If TypeOf note2 Is Printable Then
Dim isNote2 As Printable = note2
isNote2.Read( )
isNote2.Write( )
End If
Console.WriteLine(vbCrLf)
note2.Read( )
note2.Write( )
End Sub
End Class</source>
<pre class=codeResult>Creating document with: Test Note
Creating note with: Test Note
Overriding the Read method for Note!
Document Write Method for Printable

Overriding the Read method for Note!
Document Write Method for Printable

Creating document with: Second Test
Creating note with: Second Test
Overriding the Read method for Note!
Document Write Method for Printable

Overriding the Read method for Note!
Implementing the Write method for Note!</pre>

==Overrides Overridable methods==

<source lang="vbnet">Option Strict On
Imports System
Public Class Control
Public Sub New(ByVal top As Integer, ByVal left As Integer)
Me.top = top
Me.left = left
End Sub
Public Overridable Sub DrawControl( )
Console.WriteLine("Control: drawing Control at {0}, {1}", top, left)
End Sub
Protected top As Integer
Protected left As Integer
End Class
Public Class Label
Inherits Control
Public Sub New(ByVal top As Integer, ByVal left As Integer, ByVal n As String)
MyBase.New(top, left)
text = n
End Sub
Public Overrides Sub DrawControl( )
MyBase.DrawControl( )
Console.WriteLine("Writing string to the listbox: {0}", text)
End Sub
Private text As String
End Class
Public Class Button
Inherits Control
Public Sub New(ByVal top As Integer, ByVal left As Integer)
MyBase.New(top, left)
End Sub "New
Public Overrides Sub DrawControl( )
Console.WriteLine("Drawing a button at {0}, {1}" + ControlChars.Lf, top, Left)
End Sub
End Class
Public Class Tester
Shared Sub Main( )
Dim win As New Control(1, 2)
Dim lb As New Label(3, 4, "test")
Dim b As New Button(5, 6)
win.DrawControl( )
lb.DrawControl( )
b.DrawControl( )

Dim winArray(3) As Control
winArray(0) = New Control(1, 2)
winArray(1) = New Label(3, 4, "AAA")
winArray(2) = New Button(5, 6)
Dim i As Integer
For i = 0 To 2
winArray(i).DrawControl( )
Next i
End Sub
End Class</source>
<pre class=codeResult>Control: drawing Control at 1, 2
Control: drawing Control at 3, 4
Writing string to the listbox: test
Drawing a button at 5, 6
Control: drawing Control at 1, 2
Control: drawing Control at 3, 4
Writing string to the listbox: AAA
Drawing a button at 5, 6</pre>

==ToString method overrides==

<source lang="vbnet">Module Module1
Class Phone
Public Number As String
Public Sub New(ByVal Number As String)
Me.Number = Number
End Sub
Public Overrides Function ToString() As String
ToString = Number
End Function
End Class
Sub Main()
Dim MyPhone As New Phone("555-1212")
Console.WriteLine(MyPhone)
Console.WriteLine(MyPhone.ToString())
End Sub
End Module</source>
<pre class=codeResult>555-1212
555-1212</pre>

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в 16:40, 26 мая 2010

Admin: 1 версия