一個關于委托的例子(排序)

Public Class frmDelegate

    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()

        MyBase.New()

        'This call is required by the Windows Form Designer.

        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.

    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)

        If disposing Then

            If Not (components Is Nothing) Then

                components.Dispose()

            End If

        End If

        MyBase.Dispose(disposing)

    End Sub

    'Required by the Windows Form Designer

    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer

    'It can be modified using the Windows Form Designer. 

    'Do not modify it using the code editor.

    Friend WithEvents Button1 As System.Windows.Forms.Button

    Friend WithEvents Button2 As System.Windows.Forms.Button

    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox

    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

        Me.Button1 = New System.Windows.Forms.Button

        Me.Button2 = New System.Windows.Forms.Button

        Me.TextBox1 = New System.Windows.Forms.TextBox

        Me.SuspendLayout()

        '

        'Button1

        '

        Me.Button1.Location = New System.Drawing.Point(16, 24)

        Me.Button1.Name = "Button1"

        Me.Button1.Size = New System.Drawing.Size(328, 23)

        Me.Button1.TabIndex = 0

        Me.Button1.Text = "降序排列"

        '

        'Button2

        '

        Me.Button2.Location = New System.Drawing.Point(16, 56)

        Me.Button2.Name = "Button2"

        Me.Button2.Size = New System.Drawing.Size(328, 23)

        Me.Button2.TabIndex = 1

        Me.Button2.Text = "升序排列"

        '

        'TextBox1

        '

        Me.TextBox1.BackColor = System.Drawing.SystemColors.HighlightText

        Me.TextBox1.Location = New System.Drawing.Point(16, 96)

        Me.TextBox1.Name = "TextBox1"

        Me.TextBox1.ReadOnly = True

        Me.TextBox1.Size = New System.Drawing.Size(328, 21)

        Me.TextBox1.TabIndex = 2

        Me.TextBox1.Text = "TextBox1"

        '

        'frmDelegate

        '

        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)

        Me.ClientSize = New System.Drawing.Size(360, 130)

        Me.Controls.Add(Me.TextBox1)

        Me.Controls.Add(Me.Button2)

        Me.Controls.Add(Me.Button1)

        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedToolWindow

        Me.Name = "frmDelegate"

        Me.Text = "一個關于委托的排序算法"

        Me.ResumeLayout(False)

    End Sub

#End Region

    Dim c As New Class1

    Dim i As Object

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        TextBox1.Text = ""

        c.DESCArray()

        For Each i In c.arr1

            TextBox1.Text &= i.ToString & ", "

        Next

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        TextBox1.Text = ""

        c.ASCArray()

        For Each i In c.arr1

            TextBox1.Text &= i.ToString & ", "

        Next

    End Sub

    Private Sub frmDelegate_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        TextBox1.Text = ""

        For Each i In c.arr1

            TextBox1.Text &= i.ToString & ", "

        Next

    End Sub

End Class

Class Class1

    Public arr1() As Object = {1, 86, 5, 3, 2, 7, 23, 12, 0, 55, 5, 25, 99, 51}

    'Public arr1() As Object = {"E", "B", "e", "D", "EE", "F", "CC", "DD", "A", "AA", "BCD", "a", "bb"}

    Private sort As New SortClass

    Sub DESCArray()

        sort.sort(AddressOf sort.greaterThan, arr1)

    End Sub

    Sub ASCArray()

        sort.sort(AddressOf sort.lessThan, arr1)

    End Sub

    Private Class SortClass

        Delegate Function Compare(ByVal x, ByVal y) As Boolean

        Function greaterThan(ByVal X, ByVal Y) As Boolean

            If X > Y Then

                Return True

            Else

                Return False

            End If

        End Function

        Function lessThan(ByVal X, ByVal Y) As Boolean

            If X > Y Then

                Return False

            Else

                Return True

            End If

        End Function

        Sub sort(ByVal isCompare As Compare, ByVal array() As Object)

            Dim tmp As Object

            Dim i, j As Integer

            For i = 0 To array.Length - 1

                For j = (i + 1) To array.Length - 1

                    If isCompare.Invoke(array(j), array(i)) Then

                        tmp = array(i)

                        array(i) = array(j)

                        array(j) = tmp

                    End If

                Next j

            Next i

        End Sub

    End Class

End Class

程式運作結果