Validate TextBox: cannot be empty : Regular Expressions « Development « VB.Net

Validate TextBox: cannot be empty

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Public Class MainClass
    Shared Sub Main()
        Dim form1 As Form = New Form1


    End Sub
End Class

Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()

        'This call is required by the Windows Form Designer.

        '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
            End If
        End If
    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 txtLastName As System.Windows.Forms.TextBox
    Friend WithEvents txtFirstName As System.Windows.Forms.TextBox
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents GroupBox1 As System.Windows.Forms.GroupBox
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button()
        Me.txtLastName = New System.Windows.Forms.TextBox()
        Me.txtFirstName = New System.Windows.Forms.TextBox()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.Label2 = New System.Windows.Forms.Label()
        Me.GroupBox1 = New System.Windows.Forms.GroupBox()
        Me.Button1.Location = New System.Drawing.Point(152, 204)
        Me.Button1.Name = "Button1"
        Me.Button1.Size = New System.Drawing.Size(76, 24)
        Me.Button1.TabIndex = 6
        Me.Button1.Text = "OK"
        Me.txtLastName.Location = New System.Drawing.Point(84, 48)
        Me.txtLastName.Name = "txtLastName"
        Me.txtLastName.Size = New System.Drawing.Size(152, 21)
        Me.txtLastName.TabIndex = 5
        Me.txtLastName.Text = ""
        Me.txtFirstName.Location = New System.Drawing.Point(84, 24)
        Me.txtFirstName.Name = "txtFirstName"
        Me.txtFirstName.Size = New System.Drawing.Size(152, 21)
        Me.txtFirstName.TabIndex = 4
        Me.txtFirstName.Text = ""
        Me.Label1.Location = New System.Drawing.Point(16, 28)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(64, 16)
        Me.Label1.TabIndex = 7
        Me.Label1.Text = "First Name:"
        Me.Label2.Location = New System.Drawing.Point(16, 52)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(64, 16)
        Me.Label2.TabIndex = 8
        Me.Label2.Text = "Last Name:"
        Me.GroupBox1.Controls.AddRange(New System.Windows.Forms.Control() {Me.Label2, Me.Label1, Me.txtFirstName, Me.txtLastName})
        Me.GroupBox1.Location = New System.Drawing.Point(8, 8)
        Me.GroupBox1.Name = "GroupBox1"
        Me.GroupBox1.Size = New System.Drawing.Size(368, 88)
        Me.GroupBox1.TabIndex = 9
        Me.GroupBox1.TabStop = False
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 14)
        Me.CausesValidation = False
        Me.ClientSize = New System.Drawing.Size(384, 238)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.GroupBox1, Me.Button1})
        Me.Font = New System.Drawing.Font("Tahoma", 8.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Name = "SimpleValidation"
        Me.Text = "SimpleValidation"

    End Sub

#End Region

    Private Sub txtName_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtFirstName.Validating, txtLastName.Validating
        If CType(sender, TextBox).Text = "" Then
            MessageBox.Show("You have to type something.", "Invalid Input", MessageBoxButtons.OK, MessageBoxIcon.Warning)
            e.Cancel = True
        End If
    End Sub

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


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