ErrorProvider Class
Assembly: System.Windows.Forms (in system.windows.forms.dll)
'Declaration Public Class ErrorProvider Inherits Component Implements IExtenderProvider, ISupportInitialize 'Usage Dim instance As ErrorProvider
public class ErrorProvider extends Component implements IExtenderProvider, ISupportInitialize
public class ErrorProvider extends Component implements IExtenderProvider, ISupportInitialize
ErrorProvider presents a simple mechanism for indicating to the end user that a control on a form has an error associated with it. If an error description string is specified for the control, an icon appears next to the control. The icon flashes in the manner specified by BlinkStyle, at the rate specified by BlinkRate. When the mouse hovers over the icon, a ToolTip appears showing the error description string.
Typically, you use ErrorProvider in association with data-bound controls. When using ErrorProvider with data-bound controls, you must specify the ContainerControl, either in the constructor or by setting the ContainerControl property.
Note |
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| The ErrorProvider component does not provide built-in support for accessibility clients. To make your application accessible when using this component, you must provide an additional, accessible feedback mechanism. |
The following code example demonstrates using the ErrorProvider class to notify the user of a data entry error. The example creates a Form that contains a TextBox control, a NumericUpDown control, and a ComboBox control, each validating its content, and an ErrorProvider for each control. The example sets error icon options using the BlinkRate and BlinkStyle properties and the SetIconAlignment and SetIconPadding methods. The SetError method is called with or without appropriate error text during a control’s Validated event, depending upon the content in the control.
Imports System Imports System.Drawing Imports System.Windows.Forms Namespace ErrorProvider Public NotInheritable Class Form1 Inherits System.Windows.Forms.Form Private label1 As System.Windows.Forms.Label Private label2 As System.Windows.Forms.Label Private label3 As System.Windows.Forms.Label Private label4 As System.Windows.Forms.Label Private label5 As System.Windows.Forms.Label Private label6 As System.Windows.Forms.Label Friend WithEvents favoriteColorComboBox As System.Windows.Forms.ComboBox Friend WithEvents nameTextBox1 As System.Windows.Forms.TextBox Friend WithEvents ageUpDownPicker As System.Windows.Forms.NumericUpDown Private ageErrorProvider As System.Windows.Forms.ErrorProvider Private nameErrorProvider As System.Windows.Forms.ErrorProvider Private favoriteColorErrorProvider As System.Windows.Forms.ErrorProvider <System.STAThread()> _ Public Shared Sub Main() System.Windows.Forms.Application.Run(New Form1()) End Sub 'Main Public Sub New() Me.nameTextBox1 = New System.Windows.Forms.TextBox() Me.label1 = New System.Windows.Forms.Label() Me.label2 = New System.Windows.Forms.Label() Me.ageUpDownPicker = New System.Windows.Forms.NumericUpDown() Me.favoriteColorComboBox = New System.Windows.Forms.ComboBox() Me.label3 = New System.Windows.Forms.Label() Me.label4 = New System.Windows.Forms.Label() Me.label5 = New System.Windows.Forms.Label() Me.label6 = New System.Windows.Forms.Label() ' Name Label Me.label1.Location = New System.Drawing.Point(56, 32) Me.label1.Size = New System.Drawing.Size(40, 23) Me.label1.Text = "Name:" ' Age Label Me.label2.Location = New System.Drawing.Point(40, 64) Me.label2.Size = New System.Drawing.Size(56, 23) Me.label2.Text = "Age (3-5)" ' Favorite Color Label Me.label3.Location = New System.Drawing.Point(24, 96) Me.label3.Size = New System.Drawing.Size(80, 24) Me.label3.Text = "Favorite color" ' ErrorBlinkStyle.AlwaysBlink Label Me.label4.Location = New System.Drawing.Point(264, 32) Me.label4.Size = New System.Drawing.Size(160, 23) Me.label4.Text = "ErrorBlinkStyle.AlwaysBlink" ' ErrorBlinkStyle.BlinkIfDifferentError Label Me.label5.Location = New System.Drawing.Point(264, 64) Me.label5.Size = New System.Drawing.Size(200, 23) Me.label5.Text = "ErrorBlinkStyle.BlinkIfDifferentError" ' ErrorBlinkStyle.NeverBlink Label Me.label6.Location = New System.Drawing.Point(264, 96) Me.label6.Size = New System.Drawing.Size(200, 23) Me.label6.Text = "ErrorBlinkStyle.NeverBlink" ' Name TextBox Me.nameTextBox1.Location = New System.Drawing.Point(112, 32) Me.nameTextBox1.Size = New System.Drawing.Size(120, 20) Me.nameTextBox1.TabIndex = 0 ' Age NumericUpDown Me.ageUpDownPicker.Location = New System.Drawing.Point(112, 64) Me.ageUpDownPicker.Maximum = New System.Decimal(New Integer() {150, 0, 0, 0}) Me.ageUpDownPicker.TabIndex = 4 ' Favorite Color ComboBox Me.favoriteColorComboBox.Items.AddRange(New Object() {"None", "Red", "Yellow", _ "Green", "Blue", "Purple"}) Me.favoriteColorComboBox.Location = New System.Drawing.Point(112, 96) Me.favoriteColorComboBox.Size = New System.Drawing.Size(120, 21) Me.favoriteColorComboBox.TabIndex = 5 ' Set up how the form should be displayed and add the controls to the form. Me.ClientSize = New System.Drawing.Size(464, 150) Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.label6, Me.label5, Me.label4, _ Me.label3, Me.favoriteColorComboBox, Me.ageUpDownPicker, Me.label2, _ Me.label1, Me.nameTextBox1}) Me.Text = "Error Provider Example" ' Create and set the ErrorProvider for each data entry control. nameErrorProvider = New System.Windows.Forms.ErrorProvider() nameErrorProvider.SetIconAlignment(Me.nameTextBox1, ErrorIconAlignment.MiddleRight) nameErrorProvider.SetIconPadding(Me.nameTextBox1, 2) nameErrorProvider.BlinkRate = 1000 nameErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.AlwaysBlink ageErrorProvider = New System.Windows.Forms.ErrorProvider() ageErrorProvider.SetIconAlignment(Me.ageUpDownPicker, ErrorIconAlignment.MiddleRight) ageErrorProvider.SetIconPadding(Me.ageUpDownPicker, 2) ageErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.BlinkIfDifferentError favoriteColorErrorProvider = New System.Windows.Forms.ErrorProvider() favoriteColorErrorProvider.SetIconAlignment(Me.favoriteColorComboBox, ErrorIconAlignment.MiddleRight) favoriteColorErrorProvider.SetIconPadding(Me.favoriteColorComboBox, 2) favoriteColorErrorProvider.BlinkRate = 1000 favoriteColorErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.NeverBlink End Sub 'New Private Sub nameTextBox1_Validated(sender As Object, e As System.EventArgs) Handles nameTextBox1.Validated If IsNameValid() Then ' Clear the error, if any, in the error provider. nameErrorProvider.SetError(Me.nameTextBox1, "") Else ' Set the error if the name is not valid. nameErrorProvider.SetError(Me.nameTextBox1, "Name is required.") End If End Sub Private Sub ageUpDownPicker_Validated(sender As Object, e As System.EventArgs) Handles ageUpDownPicker.Validated If IsAgeTooYoung() Then ' Set the error if the age is too young. ageErrorProvider.SetError(Me.ageUpDownPicker, "Age not old enough") ElseIf IsAgeTooOld() Then ' Set the error if the age is too old. ageErrorProvider.SetError(Me.ageUpDownPicker, "Age is too old") Else ' Clear the error, if any, in the error provider. ageErrorProvider.SetError(Me.ageUpDownPicker, "") End If End Sub Private Sub favoriteColorComboBox_Validated(sender As Object, e As System.EventArgs) Handles favoriteColorComboBox.Validated If Not IsColorValid() Then ' Set the error if the favorite color is not valid. favoriteColorErrorProvider.SetError(Me.favoriteColorComboBox, "Must select a color.") Else ' Clear the error, if any, in the error provider. favoriteColorErrorProvider.SetError(Me.favoriteColorComboBox, "") End If End Sub ' Functions to verify data. Private Function IsNameValid() As Boolean ' Determine whether the text box contains a zero-length string. Return nameTextBox1.Text.Length > 0 End Function Private Function IsAgeTooYoung() As Boolean ' Determine whether the age value is less than three. Return ageUpDownPicker.Value < 3 End Function Private Function IsAgeTooOld() As Boolean ' Determine whether the age value is greater than five. Return ageUpDownPicker.Value > 5 End Function Private Function IsColorValid() As Boolean ' Determine whether the favorite color has a valid value. If Not (favoriteColorComboBox.SelectedItem Is Nothing) Then If Not(favoriteColorComboBox.SelectedItem.ToString().Equals("None")) Then Return true End If End If Return false End Function End Class 'Form1 End Namespace 'ErrorProvider
package ErrorProvider;
import System.*;
import System.Drawing.*;
import System.Windows.Forms.*;
public class Form1 extends System.Windows.Forms.Form
{
private System.Windows.Forms.Label label1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.Label label4;
private System.Windows.Forms.Label label5;
private System.Windows.Forms.Label label6;
private System.Windows.Forms.Label label3;
private System.Windows.Forms.TextBox nameTextBox1;
private System.Windows.Forms.NumericUpDown ageUpDownPicker;
private System.Windows.Forms.ComboBox favoriteColorComboBox;
private System.Windows.Forms.ErrorProvider ageErrorProvider;
private System.Windows.Forms.ErrorProvider nameErrorProvider;
private System.Windows.Forms.ErrorProvider favoriteColorErrorProvider;
/** @attribute STAThread()
*/
public static void main(String[] args)
{
Application.Run(new Form1());
} //main
public Form1()
{
this.nameTextBox1 = new System.Windows.Forms.TextBox();
this.label1 = new System.Windows.Forms.Label();
this.label2 = new System.Windows.Forms.Label();
this.ageUpDownPicker = new System.Windows.Forms.NumericUpDown();
this.favoriteColorComboBox = new System.Windows.Forms.ComboBox();
this.label3 = new System.Windows.Forms.Label();
this.label4 = new System.Windows.Forms.Label();
this.label5 = new System.Windows.Forms.Label();
this.label6 = new System.Windows.Forms.Label();
// Name Label
this.label1.set_Location(new System.Drawing.Point(56, 32));
this.label1.set_Size(new System.Drawing.Size(40, 23));
this.label1.set_Text("Name:");
// Age Label
this.label2.set_Location(new System.Drawing.Point(40, 64));
this.label2.set_Size(new System.Drawing.Size(56, 23));
this.label2.set_Text("Age (3-5)");
// Favorite Color Label
this.label3.set_Location(new System.Drawing.Point(24, 96));
this.label3.set_Size(new System.Drawing.Size(80, 24));
this.label3.set_Text("Favorite color");
// ErrorBlinkStyle.AlwaysBlink Label
this.label4.set_Location(new System.Drawing.Point(264, 32));
this.label4.set_Size(new System.Drawing.Size(160, 23));
this.label4.set_Text("ErrorBlinkStyle.AlwaysBlink");
// ErrorBlinkStyle.BlinkIfDifferentError Label
this.label5.set_Location(new System.Drawing.Point(264, 64));
this.label5.set_Size(new System.Drawing.Size(200, 23));
this.label5.set_Text("ErrorBlinkStyle.BlinkIfDifferentError");
// ErrorBlinkStyle.NeverBlink Label
this.label6.set_Location(new System.Drawing.Point(264, 96));
this.label6.set_Size(new System.Drawing.Size(200, 23));
this.label6.set_Text("ErrorBlinkStyle.NeverBlink");
// Name TextBox
this.nameTextBox1.set_Location(new System.Drawing.Point(112, 32));
this.nameTextBox1.set_Size(new System.Drawing.Size(120, 20));
this.nameTextBox1.set_TabIndex(0);
this.nameTextBox1.add_Validated(new System.EventHandler(
this.nameTextBox1_Validated));
// Age NumericUpDown
this.ageUpDownPicker.set_Location(new System.Drawing.Point(112, 64));
this.ageUpDownPicker.set_Maximum(new System.Decimal(new int[] {
150, 0, 0, 0 }));
this.ageUpDownPicker.set_TabIndex(4);
this.ageUpDownPicker.add_Validated(new System.EventHandler(
this.ageUpDownPicker_Validated));
// Favorite Color ComboBox
this.favoriteColorComboBox.get_Items().AddRange(new Object[] {
"None", "Red", "Yellow", "Green", "Blue", "Purple" });
this.favoriteColorComboBox.set_Location(
new System.Drawing.Point(112, 96));
this.favoriteColorComboBox.set_Size(new System.Drawing.Size(120, 21));
this.favoriteColorComboBox.set_TabIndex(5);
this.favoriteColorComboBox.add_Validated(new System.EventHandler(
this.favoriteColorComboBox_Validated));
// Set up how the form should be displayed and add the controls to
// the form.
this.set_ClientSize(new System.Drawing.Size(464, 150));
this.get_Controls().AddRange(new System.Windows.Forms.Control[] {
this.label6, this.label5, this.label4, this.label3,
this.favoriteColorComboBox, this.ageUpDownPicker, this.label2,
this.label1, this.nameTextBox1 });
this.set_Text("Error Provider Example");
// Create and set the ErrorProvider for each data entry control.
nameErrorProvider = new System.Windows.Forms.ErrorProvider();
nameErrorProvider.SetIconAlignment(this.nameTextBox1,
ErrorIconAlignment.MiddleRight);
nameErrorProvider.SetIconPadding(this.nameTextBox1, 2);
nameErrorProvider.set_BlinkRate(1000);
nameErrorProvider.set_BlinkStyle(
System.Windows.Forms.ErrorBlinkStyle.AlwaysBlink);
nameErrorProvider.set_ContainerControl(this);
ageErrorProvider = new System.Windows.Forms.ErrorProvider();
ageErrorProvider.SetIconAlignment(this.ageUpDownPicker,
ErrorIconAlignment.MiddleRight);
ageErrorProvider.SetIconPadding(this.ageUpDownPicker, 2);
ageErrorProvider.set_BlinkStyle(
System.Windows.Forms.ErrorBlinkStyle.BlinkIfDifferentError);
ageErrorProvider.set_ContainerControl(this);
favoriteColorErrorProvider = new System.Windows.Forms.ErrorProvider();
favoriteColorErrorProvider.SetIconAlignment(this.favoriteColorComboBox,
ErrorIconAlignment.MiddleRight);
favoriteColorErrorProvider.SetIconPadding(this.favoriteColorComboBox, 2);
favoriteColorErrorProvider.set_BlinkRate(1000);
favoriteColorErrorProvider.set_BlinkStyle(
System.Windows.Forms.ErrorBlinkStyle.NeverBlink);
favoriteColorErrorProvider.set_ContainerControl(this);
} //Form1
private void nameTextBox1_Validated(Object sender, System.EventArgs e)
{
if (IsNameValid()) {
// Clear the error, if any, in the error provider.
nameErrorProvider.SetError(this.nameTextBox1, "");
}
else {
// Set the error if the name is not valid.
nameErrorProvider.SetError(this.nameTextBox1, "Name is required.");
}
} //nameTextBox1_Validated
private void ageUpDownPicker_Validated(Object sender, System.EventArgs e)
{
if (IsAgeTooYoung()) {
// Set the error if the age is too young.
ageErrorProvider.SetError(this.ageUpDownPicker,
"Age not old enough");
}
else {
if (IsAgeTooOld()) {
// Set the error if the age is too old.
ageErrorProvider.SetError(this.ageUpDownPicker,
"Age is too old");
}
else {
// Clear the error, if any, in the error provider.
ageErrorProvider.SetError(this.ageUpDownPicker, "");
}
}
} //ageUpDownPicker_Validated
private void favoriteColorComboBox_Validated(Object sender,
System.EventArgs e)
{
if (!(IsColorValid())) {
// Set the error if the favorite color is not valid.
favoriteColorErrorProvider.SetError(this.favoriteColorComboBox,
"Must select a color.");
}
else {
// Clear the error, if any, in the error provider.
favoriteColorErrorProvider.SetError(
this.favoriteColorComboBox, "");
}
} //favoriteColorComboBox_Validated
// Functions to verify data.
private boolean IsNameValid()
{
// Determine whether the text box contains a zero-length string.
return ((nameTextBox1.get_Text().get_Length()) > 0);
} //IsNameValid
private boolean IsAgeTooYoung()
{
// Determine whether the age value is less than three.
return (System.Convert.ToInt32(ageUpDownPicker.get_Value()) < 3);
} //IsAgeTooYoung
private boolean IsAgeTooOld()
{
// Determine whether the age value is greater than five.
return (System.Convert.ToInt32(ageUpDownPicker.get_Value()) > 5);
} //IsAgeTooOld
private boolean IsColorValid()
{
// Determine whether the favorite color has a valid value.
return (favoriteColorComboBox.get_SelectedItem() != null)
&& (!(favoriteColorComboBox.get_SelectedItem().
ToString().Equals("None")));
} //IsColorValid
} //Form1
The following code example shows how to use the ErrorProvider with a DataSource and DataMember to indicate a data error to the user.
Private Sub InitializeComponent() ' Standard control setup. '.... ' You set the DataSource to a data set, and the DataMember to a table. errorProvider1.DataSource = dataSet1 errorProvider1.DataMember = dataTable1.TableName errorProvider1.ContainerControl = Me errorProvider1.BlinkRate = 200 End Sub 'InitializeComponent '... ' Since the ErrorProvider control does not have a visible component, ' it does not need to be added to the form. Private Sub buttonSave_Click(ByVal sender As Object, ByVal e As System.EventArgs) ' Checks for a bad post code. Dim CustomersTable As DataTable CustomersTable = customersDataSet1.Tables("Customers") Dim row As DataRow For Each row In CustomersTable.Rows If Convert.ToBoolean(row("PostalCodeIsNull")) Then row.RowError = "The Customer details contain errors" row.SetColumnError("PostalCode", "Postal Code required") End If Next row End Sub 'buttonSave_Click
private void InitializeComponent()
{
// Standard control setup.
//....
// You set the DataSource to a data set, and the DataMember
// to a table.
errorProvider1.set_DataSource(dataSet1);
errorProvider1.set_DataMember(dataTable1.get_TableName());
errorProvider1.set_ContainerControl(this);
errorProvider1.set_BlinkRate(200);
//...
// Since the ErrorProvider control does not have a visible component,
// it does not need to be added to the form.
} //InitializeComponent
protected void buttonSave_Click(Object sender, System.EventArgs e)
{
// Checks for a bad post code.
DataTable customersTable;
customersTable = customersDataSet1.get_Tables().get_Item("Customers");
for (int iCtr = 0; iCtr < customersTable.get_Rows().get_Count();
iCtr++) {
DataRow row = customersTable.get_Rows().get_Item(iCtr);
if (Convert.ToBoolean(row.get_Item("PostalCodeIsNull"))) {
row.set_RowError("The Customer details contain errors");
row.SetColumnError("PostalCode", "Postal Code required");
}
}
} //buttonSave_Click
System.MarshalByRefObject
System.ComponentModel.Component
System.Windows.Forms.ErrorProvider
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
Note