一个关于委托的例子(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 = "一个关于委托的排序算法"
        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

程序运行结果