VB.Net Tutorial/Class Module/Object — различия между версиями

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Текущая версия на 12:55, 26 мая 2010

Assign string value to an Object variable

public class Test
   public Shared Sub Main
        Dim objMyModemSpeed As Object
        objMyModemSpeed = "28.8"
        Console.WriteLine(objMyModemSpeed)
        Console.WriteLine(objMyModemSpeed * 1000 / 8)
        objMyModemSpeed = Nothing

   End Sub
End class
28.8
3600

Object lifetime

Imports System
Imports Microsoft.VisualBasic
Module MyModule
  Sub Main()
    Dim object1 As New MyClass1(1)
    object1. CheckDisposal ()
    object1.Dispose()
    object1.CheckDisposal()
    object1.Dispose()
    Dim object2 As New MyClass1(2)
  End Sub
End Module

Class MyClass1
  Implements IDisposable
  Private name As String
  Private disposed As Boolean
  Public Sub New(ByVal n As String)
    name = n
    disposed = False
    Console.WriteLine("Constructor for {0}", name)
  End Sub
  Public Sub CheckDisposal()
    If Not disposed
       Console.WriteLine("{0} still in use", name)
    End If
  End Sub
  Public Sub Dispose() Implements IDisposable.Dispose
    If Not disposed Then
      Console.WriteLine("Dispose for {0}" & vbCrLf, name)
      disposed = True
      GC.SuppressFinalize(Me)
    End If
  End Sub
  Protected Overrides Sub Finalize()
    Console.WriteLine("Destructor for {0}", name)
    Dispose()
  End Sub
End Class
Constructor for 1
1 still in use
Dispose for 1
Constructor for 2
Destructor for 2
Dispose for 2

Reference Equality

Imports System
Module Test
  Sub Main()
    Dim f as New Class1("A", 1)
    Dim f2 as New Class1("A", 1)
    Console.WriteLine(f2.Equals(f))   
    f = f2
    Console.WriteLine(f2.Equals(f))   
  End Sub
End Module
Public Class Class1
  Private Name as String
  Private Value as Integer
  Public Sub New(Name as String, Value as Integer)
    Me.Name = Name
    Me.Value = Value
  End Sub
  Public Overrides Function ToString() as String
    Return(Name & " has the value " & Value)
  End Function
End Class
False
True