VB.Net Tutorial/Development/Finalize — различия между версиями
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Текущая версия на 12:53, 26 мая 2010
Display order in which base-class and derived-class constructors and finalizers are called
Module Tester
Sub Main()
Dim circle1, circle2 As Circle
circle1 = New Circle(72, 29, 4.5) " instantiate objects
circle2 = New Circle(5, 5, 10)
circle1 = Nothing " mark objects for garbage collection
circle2 = Nothing
System.GC.Collect() " request garbage collector to execute
End Sub " Main
End Module
Public Class Point
Private mX, mY As Integer
Public Sub New()
Console.WriteLine("Point constructor: {0}", Me)
End Sub " New
Public Sub New(ByVal xValue As Integer, _
ByVal yValue As Integer)
Console.WriteLine("Point constructor: {0}", Me)
End Sub " New
Protected Overrides Sub Finalize()
Console.WriteLine("Point Finalizer: {0}", Me)
MyBase.Finalize() " call Object finalizer
End Sub
" return String representation of Point
Public Overrides Function ToString() As String
Return "[" & mX & ", " & mY & "]"
End Function " ToString
End Class
Public Class Circle
Inherits Point
Private mRadius As Double
Public Sub New()
Console.WriteLine("Circle constructor: {0}", Me)
End Sub " New
Public Sub New(ByVal xValue As Integer, _
ByVal yValue As Integer, ByVal radiusValue As Double)
MyBase.New(xValue, yValue)
Console.WriteLine("Circle constructor: {0}", Me)
End Sub " New
Protected Overrides Sub Finalize()
Console.WriteLine("Circle Finalizer: {0}", Me)
MyBase.Finalize() " call Point finalizer
End Sub " Finalize
Public Overrides Function ToString() As String
Return "Center = " & MyBase.ToString() & _
"; Radius = " & mRadius
End Function " ToString
End Class
Point constructor: Center = [0, 0]; Radius = 0 Circle constructor: Center = [0, 0]; Radius = 0 Point constructor: Center = [0, 0]; Radius = 0 Circle constructor: Center = [0, 0]; Radius = 0 Circle Finalizer: Center = [0, 0]; Radius = 0 Point Finalizer: Center = [0, 0]; Radius = 0 Circle Finalizer: Center = [0, 0]; Radius = 0 Point Finalizer: Center = [0, 0]; Radius = 0
Override Finalize method
Public Class Numbered
Private m_Number As Integer
Public Sub New(ByVal my_number As Integer)
m_Number = my_number
End Sub
" Garbage collection started.
Protected Overrides Sub Finalize()
Console.WriteLine("Finalize Number: " & m_Number)
End Sub
End Class
public class Test
public Shared Sub Main
Dim new_numbered As New Numbered(1)
new_numbered = New Numbered(2)
End Sub
End class
Finalize Number: 2 Finalize Number: 1