в 16:40, 26 мая 2010

2010-05-26T16:40:30Z

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2010-05-26T12:55:44Z

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==Call member method in constructor==

<source lang="vbnet">Option Strict On
Public Class Counters
Dim ctr As Integer
Public Sub New()
For ctr = 1 to 20
DoSomething()
Next
End Sub

Public Sub DoSomething()
Console.WriteLine(Me.ctr)
End Sub
End Class
Public Module modMain
Public Sub Main()
Dim obj As New Counters()
End Sub
End Module</source>
<pre class=codeResult>1
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20</pre>

==Class with constructor==

<source lang="vbnet">Option Strict On
Imports System
Public Class Time
" Private variables
Private Year As Integer
Private Month As Integer
Private mDate As Integer
Private Hour As Integer
Private Minute As Integer
Private Second As Integer
" Public methods
Public Sub DisplayCurrentTime( )
System.Console.WriteLine("{0}/{1}/{2} {3}:{4}:{5}", Month, mDate, Year, Hour, Minute, Second)
End Sub "DisplayCurrentTime
" Constructor
Public Sub New(ByVal theYear As Integer,ByVal theMonth As Integer, _
ByVal theDate As Integer, ByVal theHour As Integer, _
ByVal theMinute As Integer, ByVal theSecond As Integer)
Year = theYear
Month = theMonth
mDate = theDate
Hour = theHour
Minute = theMinute
Second = theSecond
End Sub
End Class "Time
Module Module1
Sub Main( )
Dim timeObject As New Time(2005, 3, 25, 9, 35, 20)
timeObject.DisplayCurrentTime( )
End Sub
End Module</source>
<pre class=codeResult>3/25/2005 9:35:20</pre>

==Constructor Chain==

<source lang="vbnet">Public Class YourClass
Public Address as String = "Default"
Public City As String = "Default"
Sub New()
MyBase.New()
Console.WriteLine("YourClass Created")
End Sub
Sub New(A as String, C As String)
Me.New()
Address = A
City = C
Console.WriteLine("YourClass.Address and Set")
End Sub
End Class
Module Test
Sub Main()
Dim SL As New YourClass("123 First Street", "Somewhere")
End Sub
End Module</source>
<pre class=codeResult>YourClass Created
YourClass.Address and Set</pre>

==constructor inheriting==

<source lang="vbnet">Public Class Address
Private MyState as String = "DEFAULT"
Sub New()
MyBase.New()
Console.WriteLine("Address Created")
End Sub
Public Property State As String
Get
Return MyState
End Get
Set(Value As String)
MyState = Value
End Set
End Property
End Class
Public Class MyAddress
Inherits Address
Private MyAddress as String
Sub New()
MyBase.New()
Console.WriteLine("MyAddress Created")
End Sub
Public Property Address as String
Get
Return MyAddress
End Get
Set(Value As String)
MyAddress = Value
End Set
End Property
End Class
Module Test
Sub Main()
Dim SL As New MyAddress()
SL.State = "CANADA"
SL.Address = "123"
End Sub
End Module</source>
<pre class=codeResult>Address Created
MyAddress Created</pre>

==Constructors in three levels==

<source lang="vbnet">Class A
Public Sub New()
Console.WriteLine("In class A constructor")
End Sub
End Class
Class B
Inherits A
Public Sub New()
Console.WriteLine("In class B constructor")
End Sub
End Class
Class C
Inherits B
Public Sub New()
Console.WriteLine("In class C constructor")
End Sub
End Class
Module Module1
Sub Main()
Dim objSample As New C()
End Sub
End Module</source>
<pre class=codeResult>In class A constructor
In class B constructor
In class C constructor</pre>

==Constructor with Optional parameter==

<source lang="vbnet">Public Class Point
Private MX as Integer
Private MY as Integer
Public Sub New(Optional X As Integer = 0, Optional Y As Integer = 0)
MX = X
MY = Y
End Sub
Public Overrides Function ToString() As String
Return "(" & MX & "," & MY & ")"
End Function
End Class
Module OptionalPoint
Sub Main
Dim P1 As New Point()
Console.WriteLine(P1.ToString())
Dim P2 As New Point(1, 1)
Console.WriteLine(P2.ToString())
Dim P3 As New Point(, 1)
Console.WriteLine(P3.ToString())
Dim P4 As New Point(9, )
Console.WriteLine(P4.ToString())
End Sub
End Module</source>
<pre class=codeResult>(0,0)
(1,1)
(0,1)
(9,0)</pre>

==Copy constructor==

<source lang="vbnet">Option Strict On
Imports System
Public Class Time
" Private variables
Private Year As Integer
Private Month As Integer
Private mDate As Integer
Private Hour As Integer
Private Minute As Integer
Private Second As Integer = 30
" Public methods
Public Sub DisplayCurrentTime( )
System.Console.WriteLine("{0}/{1}/{2} {3}:{4}:{5}", _
Month, mDate, Year, Hour, Minute, Second)
End Sub "DisplayCurrentTime
Public Sub New( _
ByVal theYear As Integer, _
ByVal theMonth As Integer, _
ByVal theDate As Integer, _
ByVal theHour As Integer, _
ByVal theMinute As Integer)
Year = theYear
Month = theMonth
mDate = theDate
Hour = theHour
Minute = theMinute
End Sub
Public Sub New(existingObject As Time)
Year = existingObject.Year
Month = existingObject.Month
mDate = existingObject.mDate
Hour = existingObject.Hour
Minute = existingObject.Minute
Second = existingObject.Second
End Sub
End Class "Time
Module Module1
Sub Main( )
Dim timeObject As New Time(2005, 3, 25, 9, 35)
Dim t2 As New Time(timeObject)
timeObject.DisplayCurrentTime( )
t2.DisplayCurrentTime( )
End Sub
End Module</source>
<pre class=codeResult>3/25/2005 9:35:30
3/25/2005 9:35:30</pre>

==Default constructor==

<source lang="vbnet">Imports System
Module Test
Sub Main()
Dim p1 as New Point()
Dim p2 as New Point()
p2.Y = 100
p2.X = 100
Console.WriteLine(p1)
Console.WriteLine(p2)
End Sub
End Module
Class Point
Public X as Integer
Public Y as Integer
Public Overrides Function ToString() as String
Return("(" & X & "," & Y & ")")
End function
End Class</source>
<pre class=codeResult>(0,0)
(100,100)</pre>

==Empty constructor==

<source lang="vbnet">Imports System
Module Test
Sub Main()
Dim p1 as New Point()
Dim p2 as New Point(100,100)
Console.WriteLine(p1)
Console.WriteLine(p2)
End Sub
End Module
Class Point
Private X as Integer
Private Y as Integer
Sub New()
End Sub
Sub New(x as integer, y as Integer)
Me.X = x
Me.Y = y
End Sub
Public Overrides Function ToString() as String
Return("(" & X & "," & Y & ")")
End function
End Class</source>
<pre class=codeResult>(0,0)
(100,100)</pre>

==Inheriting Constructors==

<source lang="vbnet">Public Class Tester
Public Shared Sub Main
Dim objJohn As New John("Walking...")
objJohn.Walk()
End Sub
End Class
Public Class Person
Private Text As String
Public Sub New(ByVal Message As String)
Text = Message
End Sub
Public Sub Walk()
Console.WriteLine(Text)
End Sub
End Class
Class John
Inherits Person
Public Sub New(ByVal Message As String)
MyBase.New(Message)
End Sub
End Class</source>
<pre class=codeResult>Walking...</pre>

==Overloaded constructors==

<source lang="vbnet">Module Tester
Sub Main()
" use overloaded constructors
Dim time1 As New MyTime()
Dim time2 As New MyTime(2)
Dim time3 As New MyTime(21, 34)
Dim time4 As New MyTime(12, 25, 42)
Dim time5 As New MyTime(27, 74, 99)
Dim time6 As New MyTime(time4) " use time4 as initial value
Console.WriteLine(time1.ToUniversalString() )
Console.WriteLine(time2.ToUniversalString() )
Console.WriteLine(time3.ToUniversalString())
Console.WriteLine(time4.ToUniversalString())
Console.WriteLine(time5.ToUniversalString())
Console.WriteLine(time6.ToUniversalString())
End Sub " Main
End Module
Class MyTime
Inherits Object
Private mHour As Integer " 0 - 23
Private mMinute As Integer " 0 - 59
Private mSecond As Integer " 0 - 59
Public Sub New()
SetTime()
End Sub " New
Public Sub New(ByVal hourValue As Integer)
SetTime(hourValue)
End Sub " New
Public Sub New(ByVal hourValue As Integer, _
ByVal minuteValue As Integer)
SetTime(hourValue, minuteValue)
End Sub " New
Public Sub New(ByVal hourValue As Integer, _
ByVal minuteValue As Integer, ByVal secondValue As Integer)
SetTime(hourValue, minuteValue, secondValue)
End Sub " New
Public Sub New(ByVal timeValue As MyTime)
SetTime(timeValue.mHour, timeValue.mMinute, timeValue.mSecond)
End Sub " New
Public Sub SetTime(Optional ByVal hourValue As Integer = 0, _
Optional ByVal minuteValue As Integer = 0, _
Optional ByVal secondValue As Integer = 0)
If (hourValue >= 0 AndAlso hourValue < 24) Then
mHour = hourValue
Else
mHour = 0
End If
If (minuteValue >= 0 AndAlso minuteValue < 60) Then
mMinute = minuteValue
Else
mMinute = 0
End If
If (secondValue >= 0 AndAlso secondValue < 60) Then
mSecond = secondValue
Else
mSecond = 0
End If
End Sub " SetTime
Public Function ToUniversalString() As String
Return String.Format("{0}:{1:D2}:{2:D2}", _
mHour, mMinute, mSecond)
End Function " ToUniversalString
End Class</source>
<pre class=codeResult>0:00:00
2:00:00
21:34:00
12:25:42
0:00:00
12:25:42</pre>

==Private Constructor==

<source lang="vbnet">Public Class Util
Private Sub New()
End Sub
Public Shared Function QuoteIt(ToQuote as String, Author As String) As String
Return ToQuote + " - " + Author
End Function

Public Shared Function UpperLower(ToChange as String) As String
Dim i as Integer
Dim stringBuilder as New Text.StringBuilder(ToChange)
For i = 0 To ToChange.Length - 1
stringBuilder.Chars(i) = Char.ToUpper(stringBuilder.Chars(i))
Next
Return stringBuilder.ToString()
End Function
End Class
Module Test
Sub Main
Console.WriteLine(Util.QuoteIt("A", "B"))
Console.WriteLine(Util.UpperLower("AAaa"))
End Sub
End Module</source>
<pre class=codeResult>A - B
AAAA</pre>

==Shared Constructor==

<source lang="vbnet">Public Class YourClass
Private Shared ID as Integer = 10
Public Shared ReadOnly Property CurrentID as Integer
Get
Return ID
End Get
End Property
Public Shared Function GetID() as Integer
ID += 1
Return ID
End Function
Shared Sub New()
Console.WriteLine("Before init: " & ID)
ID = 100
Console.WriteLine("After init: " & ID)
End Sub
End Class
Module Test
Sub Main()
Dim CountValue As Integer
For CountValue = 1 to 10
Console.WriteLine(YourClass.GetID())
Next
End Sub
End Module</source>
<pre class=codeResult>Before init: 10
After init: 100
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VB.Net Tutorial/Class Module/Constructor - История изменений

в 16:40, 26 мая 2010

Admin: 1 версия