' 导入命名空间
Imports System.Windows.Forms

Public Class Form1
    Inherits Form

    Public Sub New()
        ' Create a TextBox control.
        Dim tb As New TextBox()
        Me.Controls.Add(tb)
        AddHandler tb.KeyPress, AddressOf keypressed
    End Sub

    Private Sub keypressed(ByVal o As [Object], ByVal e As KeyPressEventArgs)
        ' The keypressed method uses the KeyChar property to check 
        ' whether the ENTER key is pressed. 

        ' If the ENTER key is pressed, the Handled property is set to true, 
        ' to indicate the event is handled.

        If e.KeyChar = Microsoft.VisualBasic.ChrW(Keys.Return) Then
            e.Handled = True
        End If
    End Sub

    Public Shared Sub Main()
        Application.Run(New Form1())
    End Sub
End Class

' 导入命名空间
Imports System
Imports System.Collections
Imports System.Data
Imports System.IO
Imports System.Xml.Serialization
Imports System.Windows.Forms
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Drawing.Text
Imports System.Drawing.Printing


Public Class MainClass
    Shared Sub Main()
       Dim form1 As Form = New Form1()
       Application.Run(form1) 
    End Sub
End Class




Public Class Form1
    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
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
    Friend WithEvents Label1 As System.Windows.Forms.Label

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.Container

    '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.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.TextBox1 = New System.Windows.Forms.TextBox()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.SuspendLayout()
        '
        'TextBox1
        '
        Me.TextBox1.Font = New System.Drawing.Font("Microsoft Sans Serif", 10.2!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.TextBox1.Location = New System.Drawing.Point(48, 104)
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.Size = New System.Drawing.Size(192, 27)
        Me.TextBox1.TabIndex = 1
        Me.TextBox1.Text = ""
        '
        'Label1
        '
        Me.Label1.Font = New System.Drawing.Font("Microsoft Sans Serif", 10.2!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Label1.Location = New System.Drawing.Point(24, 24)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(232, 48)
        Me.Label1.TabIndex = 2
        Me.Label1.Text = "Type somthing"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 15)
        Me.ClientSize = New System.Drawing.Size(292, 268)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.Label1, Me.TextBox1})
        Me.Name = "Form1"
        Me.Text = "Key Event Examples"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub

    Private Sub TextBox1_KeyPress(ByVal sender As Object, _
            ByVal e As System.Windows.Forms.KeyPressEventArgs) _
            Handles TextBox1.KeyPress
        If e.KeyChar < "0" Or e.KeyChar > "9" Then
            MessageBox.Show("only digits allowed")
            e.Handled = True
        End If
    End Sub
    
End Class