VB.Net/Class/ReadOnly — различия между версиями

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Текущая версия на 12:42, 26 мая 2010

Define and use Properties: ReadOnly

Imports System
Imports System.Collections

public class MainClass
   Shared Sub Main()
        Dim obj As New MyOwnClass("Firstobject")
        Dim x As Integer
        Console.WriteLine("This object is: " & obj.Name)
        Console.WriteLine("Other objects are: ")
        For x = 0 To MyOwnClass.OtherObjectCount - 1
            If x <> obj.MyIndex Then
                Console.WriteLine(obj(x).Name)
            End If
        Next
   End Sub
End Class
    Class MyOwnClass
        Implements IDisposable
        Private Shared myclasses As New ArrayList()
        Public Name As String
        Public Sub New(ByVal myname As String)
            MyBase.New()
            MyClasses.Add(Me)
            Name = myname
        End Sub
        Default Public ReadOnly Property OtherMyClassObjects(ByVal idx As Integer) As MyClass
            Get
                Return CType(MyClasses.Item(idx), MyClass)
            End Get
        End Property
        Public Shared ReadOnly Property OtherObjectCount() As Integer
            Get
                Return myclasses.Count
            End Get
        End Property
        Public ReadOnly Property MyIndex() As Integer
            Get
                Return myclasses.IndexOf(Me)
            End Get
        End Property
        Public Sub Dispose() Implements IDisposable.Dispose
            MyClasses.Remove(Me)
        End Sub
    End Class


Define and use ReadOnly Class Property

Imports System
Imports System.IO

Public Class MainClass
  Shared Sub Main()
        Dim e As New Employee("Joe", 100000)
        Console.WriteLine(e.Name & "  has salary " & e.Salary)
        e.RaiseSalary(0.2D) "D necessary for decimal
        Console.WriteLine(e.Name & " still has salary " & e.Salary)
        Console.WriteLine()
        
  End Sub
End Class
Public Class Employee
    Private m_Name As String
    Private m_Salary As Decimal
    Private Const LIMIT As Decimal = 0.1D
    Public Sub New(ByVal theName As String, ByVal curSalary As Decimal)
        m_Name = theName
        m_Salary = curSalary
    End Sub
    ReadOnly Property Name() As String
        Get
            Return m_Name
        End Get
    End Property
    ReadOnly Property Salary() As Decimal
        Get
            Return m_Salary
        End Get
    End Property
    Public Overloads Sub RaiseSalary(ByVal Percent As Decimal)
        If Percent > LIMIT Then
            "not allowed
            Console.WriteLine("Percent > LIMIT is not allowed")
        Else
            m_Salary = (1 + Percent) * m_Salary
        End If
    End Sub
    Public Overloads Sub RaiseSalary(ByVal Percent As Decimal, _
        ByVal Password As String)
        If Password = "special" Then
            m_Salary = (1 + Percent) * m_Salary
        End If
    End Sub
End Class


Define ReadOnly Property

Imports System
Public Class MainClass
    Public Shared ReadOnly MaxEmployees As Integer = 100
    Shared Sub Main(ByVal args As String())
        Console.WriteLine(MaxEmployees)
    End Sub
End Class


Demo Const and ReadOnly

Imports System
Public Class MainClass
    Shared Sub Main(ByVal args As String())
      Dim random As Random = New Random()
      Dim circle As CircleConstants = New CircleConstants(random.Next(1, 20))
      Dim radius As String = Convert.ToString(circle.RADIUS)
      Dim output As String = "Radius = " & radius & vbCrLf _
         & "Circumference = " + String.Format("{0:N3}", _
         circle.RADIUS * 2 * CircleConstants.PI)
      Console.WriteLine(output)
      
    End Sub
End Class
" Encapsulate constants PI and radius.
Class CircleConstants
   " PI is constant data member
   Public Const PI As Double = 3.14159
   " radius is uninitialized constant
   Public ReadOnly RADIUS As Integer
   " constructor of class CircleConstants
   Public Sub New(ByVal radiusValue As Integer)
      RADIUS = radiusValue
   End Sub " New
End Class " CircleConstants