EventArgs Class
EventArgs is the base class for classes containing event data.
Assembly: mscorlib (in mscorlib.dll)
This class contains no event data; it is used by events that do not pass state information to an event handler when an event is raised. If the event handler requires state information, the application must derive a class from this class to hold the data.
For example, the System.AssemblyLoadEventArgs class is used to hold the data for assembly load events, and contains a System.Reflection.Assembly that describes the loaded assembly.
For more information about events, see the EventHandler topic.
The following code sample illustrates the use of EventArgs.
In this sample, FireEventArgs is a set of event arguments derived from EventArgs, and passed to the FireEventHandler when an event is raised by calling ActivateFireAlarm.
Imports System _ ' FireEventArgs: a custom event inherited from EventArgs. Public Class FireEventArgs Inherits EventArgs Public Sub New(room As String, ferocity As Integer) Me.room = room Me.ferocity = ferocity End Sub 'New ' The fire event will have two pieces of information-- ' 1) Where the fire is, and 2) how "ferocious" it is. Public room As String Public ferocity As Integer End Class 'FireEventArgs _ 'end of class FireEventArgs Public Class FireAlarm ' Events are handled with delegates, so we must establish a FireEventHandler ' as a delegate: Delegate Sub FireEventHandler(sender As Object, fe As FireEventArgs) ' Now, create a public event "FireEvent" whose type is our FireEventHandler delegate. Public Event FireEvent As FireEventHandler ' This will be the starting point of our event-- it will create FireEventArgs, ' and then raise the event, passing FireEventArgs. Public Sub ActivateFireAlarm(room As String, ferocity As Integer) Dim fireArgs As New FireEventArgs(room, ferocity) ' Now, raise the event by invoking the delegate. Pass in ' the object that initated the event (Me) as well as FireEventArgs. ' The call must match the signature of FireEventHandler. RaiseEvent FireEvent(Me, fireArgs) End Sub 'ActivateFireAlarm End Class 'FireAlarm ' The following event will be the EventHandler. Class FireHandlerClass ' Create a FireAlarm to handle and raise the fire events. Public Sub New(fireAlarm As FireAlarm) ' Add a delegate containing the ExtinguishFire function to the class' ' event so that when FireAlarm is raised, it will subsequently execute ' ExtinguishFire. AddHandler fireAlarm.FireEvent, AddressOf ExtinguishFire End Sub 'New ' This is the function to be executed when a fire event is raised. Sub ExtinguishFire(sender As Object, fe As FireEventArgs) Console.WriteLine() Console.WriteLine("The ExtinguishFire function was called by {0}.", sender.ToString()) ' Now, act in response to the event. If fe.ferocity < 2 Then Console.WriteLine("This fire in the {0} is no problem. I'm going to pour some water on it.", fe.room) Else If fe.ferocity < 5 Then Console.WriteLine("Using Fire Extinguisher to put out the fire in the {0}.", fe.room) Else Console.WriteLine("The fire in the {0} is out of control. I'm calling the fire department.", fe.room) End If End If 'end of class FireHandlerClass End Sub 'ExtinguishFire End Class 'FireHandlerClass Public Class FireEventTest Public Shared Sub Main() ' Create an instance of the class that will be raising the event. Dim myFireAlarm As New FireAlarm() ' Create an instance of the class that will be handling the event. Note that ' it receives the class that will fire the event as a parameter. Dim myFireHandler As New FireHandlerClass(myFireAlarm) ' Now, use the FireAlarm class to raise a few events. myFireAlarm.ActivateFireAlarm("Kitchen", 3) myFireAlarm.ActivateFireAlarm("Study", 1) myFireAlarm.ActivateFireAlarm("Porch", 5) Return End Sub 'Main 'end of main End Class 'FireEventTest ' end of FireEventTest
System.EventArgs
Microsoft.Build.Framework.BuildEventArgs
Microsoft.ManagementConsole.ActionEventArgs
Microsoft.ManagementConsole.SyncActionEventArgs
Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventArgs
Microsoft.VisualBasic.Devices.NetworkAvailableEventArgs
Microsoft.Win32.PowerModeChangedEventArgs
Microsoft.Win32.SessionEndedEventArgs
Microsoft.Win32.SessionEndingEventArgs
Microsoft.Win32.SessionSwitchEventArgs
Microsoft.Win32.TimerElapsedEventArgs
Microsoft.Win32.UserPreferenceChangedEventArgs
Microsoft.Win32.UserPreferenceChangingEventArgs
System.AssemblyLoadEventArgs
System.Collections.Specialized.NotifyCollectionChangedEventArgs
System.ComponentModel.AddingNewEventArgs
System.ComponentModel.AsyncCompletedEventArgs
System.ComponentModel.CancelEventArgs
System.ComponentModel.CollectionChangeEventArgs
System.ComponentModel.CurrentChangingEventArgs
System.ComponentModel.Design.ActiveDesignerEventArgs
System.ComponentModel.Design.ActiveDesignSurfaceChangedEventArgs
System.ComponentModel.Design.ComponentChangedEventArgs
System.ComponentModel.Design.ComponentChangingEventArgs
System.ComponentModel.Design.ComponentEventArgs
System.ComponentModel.Design.ComponentRenameEventArgs
System.ComponentModel.Design.DesignerActionListsChangedEventArgs
System.ComponentModel.Design.DesignerActionUIStateChangeEventArgs
System.ComponentModel.Design.DesignerEventArgs
System.ComponentModel.Design.DesignerTransactionCloseEventArgs
System.ComponentModel.Design.DesignSurfaceEventArgs
System.ComponentModel.Design.LoadedEventArgs
System.ComponentModel.Design.MenuCommandsChangedEventArgs
System.ComponentModel.Design.Serialization.ResolveNameEventArgs
System.ComponentModel.HandledEventArgs
System.ComponentModel.ListChangedEventArgs
System.ComponentModel.ProgressChangedEventArgs
System.ComponentModel.PropertyChangedEventArgs
System.ComponentModel.RefreshEventArgs
System.Configuration.Install.InstallEventArgs
System.Configuration.Internal.InternalConfigEventArgs
System.Configuration.SettingsLoadedEventArgs
System.ConsoleCancelEventArgs
System.Data.Common.RowUpdatedEventArgs
System.Data.Common.RowUpdatingEventArgs
System.Data.DataColumnChangeEventArgs
System.Data.DataRowChangeEventArgs
System.Data.DataTableClearEventArgs
System.Data.DataTableNewRowEventArgs
System.Data.FillErrorEventArgs
System.Data.MergeFailedEventArgs
System.Data.Odbc.OdbcInfoMessageEventArgs
System.Data.OleDb.OleDbInfoMessageEventArgs
System.Data.OracleClient.OracleInfoMessageEventArgs
System.Data.SqlClient.SqlInfoMessageEventArgs
System.Data.SqlClient.SqlNotificationEventArgs
System.Data.SqlClient.SqlRowsCopiedEventArgs
System.Data.StateChangeEventArgs
System.Data.StatementCompletedEventArgs
System.Diagnostics.DataReceivedEventArgs
System.Diagnostics.EntryWrittenEventArgs
System.Diagnostics.Eventing.Reader.EventRecordWrittenEventArgs
System.Drawing.Design.PaintValueEventArgs
System.Drawing.Design.ToolboxComponentsCreatedEventArgs
System.Drawing.Design.ToolboxComponentsCreatingEventArgs
System.Drawing.Printing.PrintPageEventArgs
System.IO.ErrorEventArgs
System.IO.FileSystemEventArgs
System.IO.Log.TailPinnedEventArgs
System.IO.Packaging.SignatureVerificationEventArgs
System.IO.Ports.SerialDataReceivedEventArgs
System.IO.Ports.SerialErrorReceivedEventArgs
System.IO.Ports.SerialPinChangedEventArgs
System.Management.ManagementEventArgs
System.Messaging.PeekCompletedEventArgs
System.Messaging.ReceiveCompletedEventArgs
System.Net.NetworkInformation.NetworkAvailabilityEventArgs
System.Net.PeerToPeer.Collaboration.ApplicationChangedEventArgs
System.Net.PeerToPeer.Collaboration.NameChangedEventArgs
System.Net.PeerToPeer.Collaboration.ObjectChangedEventArgs
System.Net.PeerToPeer.Collaboration.PeerNearMeChangedEventArgs
System.Net.PeerToPeer.Collaboration.PresenceChangedEventArgs
System.Net.PeerToPeer.Collaboration.SubscriptionListChangedEventArgs
System.Printing.PrintSystemObjectPropertiesChangedEventArgs
System.Printing.PrintSystemObjectPropertyChangedEventArgs
System.ResolveEventArgs
System.ServiceModel.UnknownMessageReceivedEventArgs
System.Speech.Recognition.AudioLevelUpdatedEventArgs
System.Speech.Recognition.AudioSignalProblemOccurredEventArgs
System.Speech.Recognition.AudioStateChangedEventArgs
System.Speech.Recognition.RecognitionEventArgs
System.Speech.Recognition.RecognizerUpdateReachedEventArgs
System.Speech.Recognition.SpeechDetectedEventArgs
System.Speech.Recognition.StateChangedEventArgs
System.Speech.Synthesis.StateChangedEventArgs
System.Threading.ThreadExceptionEventArgs
System.Timers.ElapsedEventArgs
System.Transactions.TransactionEventArgs
System.UnhandledExceptionEventArgs
System.Web.ApplicationServices.AuthenticatingEventArgs
System.Web.ApplicationServices.CreatingCookieEventArgs
System.Web.ApplicationServices.SelectingProviderEventArgs
System.Web.ApplicationServices.ValidatingPropertiesEventArgs
System.Web.ClientServices.Providers.SettingsSavedEventArgs
System.Web.ClientServices.Providers.UserValidatedEventArgs
System.Web.Compilation.BuildManagerHostUnloadEventArgs
System.Web.Profile.ProfileAutoSaveEventArgs
System.Web.Profile.ProfileEventArgs
System.Web.Profile.ProfileMigrateEventArgs
System.Web.Security.AnonymousIdentificationEventArgs
System.Web.Security.DefaultAuthenticationEventArgs
System.Web.Security.FormsAuthenticationEventArgs
System.Web.Security.PassportAuthenticationEventArgs
System.Web.Security.RoleManagerEventArgs
System.Web.Security.ValidatePasswordEventArgs
System.Web.Security.WindowsAuthenticationEventArgs
System.Web.SiteMapResolveEventArgs
System.Web.TraceContextEventArgs
System.Web.UI.AsyncPostBackErrorEventArgs
System.Web.UI.Design.DesignerRegionMouseEventArgs
System.Web.UI.Design.TemplateModeChangedEventArgs
System.Web.UI.Design.ViewEventArgs
System.Web.UI.ImageClickEventArgs
System.Web.UI.MobileControls.ListDataBindEventArgs
System.Web.UI.MobileControls.LoadItemsEventArgs
System.Web.UI.MobileControls.ObjectListDataBindEventArgs
System.Web.UI.MobileControls.ObjectListSelectEventArgs
System.Web.UI.MobileControls.ObjectListShowCommandsEventArgs
System.Web.UI.ScriptReferenceEventArgs
System.Web.UI.WebControls.AdCreatedEventArgs
System.Web.UI.WebControls.AuthenticateEventArgs
System.Web.UI.WebControls.BulletedListEventArgs
System.Web.UI.WebControls.CommandEventArgs
System.Web.UI.WebControls.CreateUserErrorEventArgs
System.Web.UI.WebControls.DataGridItemEventArgs
System.Web.UI.WebControls.DataGridPageChangedEventArgs
System.Web.UI.WebControls.DataGridSortCommandEventArgs
System.Web.UI.WebControls.DataListItemEventArgs
System.Web.UI.WebControls.DetailsViewDeletedEventArgs
System.Web.UI.WebControls.DetailsViewInsertedEventArgs
System.Web.UI.WebControls.DetailsViewUpdatedEventArgs
System.Web.UI.WebControls.FormViewDeletedEventArgs
System.Web.UI.WebControls.FormViewInsertedEventArgs
System.Web.UI.WebControls.FormViewUpdatedEventArgs
System.Web.UI.WebControls.GridViewDeletedEventArgs
System.Web.UI.WebControls.GridViewRowEventArgs
System.Web.UI.WebControls.GridViewUpdatedEventArgs
System.Web.UI.WebControls.ImageMapEventArgs
System.Web.UI.WebControls.LinqDataSourceContextEventArgs
System.Web.UI.WebControls.LinqDataSourceStatusEventArgs
System.Web.UI.WebControls.ListViewDeletedEventArgs
System.Web.UI.WebControls.ListViewInsertedEventArgs
System.Web.UI.WebControls.ListViewItemEventArgs
System.Web.UI.WebControls.ListViewUpdatedEventArgs
System.Web.UI.WebControls.LoginCancelEventArgs
System.Web.UI.WebControls.ObjectDataSourceEventArgs
System.Web.UI.WebControls.ObjectDataSourceStatusEventArgs
System.Web.UI.WebControls.PageEventArgs
System.Web.UI.WebControls.PagePropertiesChangingEventArgs
System.Web.UI.WebControls.RepeaterItemEventArgs
System.Web.UI.WebControls.SendMailErrorEventArgs
System.Web.UI.WebControls.ServerValidateEventArgs
System.Web.UI.WebControls.SiteMapNodeItemEventArgs
System.Web.UI.WebControls.SqlDataSourceStatusEventArgs
System.Web.UI.WebControls.TreeNodeEventArgs
System.Web.UI.WebControls.WebParts.WebPartAuthorizationEventArgs
System.Web.UI.WebControls.WebParts.WebPartConnectionsEventArgs
System.Web.UI.WebControls.WebParts.WebPartDisplayModeEventArgs
System.Web.UI.WebControls.WebParts.WebPartEventArgs
System.Web.UI.WebControls.WebParts.WebPartVerbsEventArgs
System.Web.UI.WebControls.WizardNavigationEventArgs
System.Windows.Annotations.AnnotationAuthorChangedEventArgs
System.Windows.Annotations.AnnotationResourceChangedEventArgs
System.Windows.Annotations.Storage.StoreContentChangedEventArgs
System.Windows.Automation.AutomationEventArgs
System.Windows.AutoResizedEventArgs
System.Windows.Controls.InkCanvasStrokesReplacedEventArgs
System.Windows.Controls.Primitives.ItemsChangedEventArgs
System.Windows.Data.FilterEventArgs
System.Windows.Documents.PagesChangedEventArgs
System.Windows.Documents.PaginationProgressEventArgs
System.Windows.Documents.Serialization.WritingCancelledEventArgs
System.Windows.Documents.Serialization.WritingPrintTicketRequiredEventArgs
System.Windows.ExitEventArgs
System.Windows.Forms.BindingManagerDataErrorEventArgs
System.Windows.Forms.CacheVirtualItemsEventArgs
System.Windows.Forms.ColumnClickEventArgs
System.Windows.Forms.ColumnWidthChangedEventArgs
System.Windows.Forms.ContentsResizedEventArgs
System.Windows.Forms.ControlEventArgs
System.Windows.Forms.ConvertEventArgs
System.Windows.Forms.DataGridViewAutoSizeColumnModeEventArgs
System.Windows.Forms.DataGridViewAutoSizeColumnsModeEventArgs
System.Windows.Forms.DataGridViewAutoSizeModeEventArgs
System.Windows.Forms.DataGridViewBindingCompleteEventArgs
System.Windows.Forms.DataGridViewCellEventArgs
System.Windows.Forms.DataGridViewCellStateChangedEventArgs
System.Windows.Forms.DataGridViewCellStyleContentChangedEventArgs
System.Windows.Forms.DataGridViewCellValueEventArgs
System.Windows.Forms.DataGridViewColumnEventArgs
System.Windows.Forms.DataGridViewColumnStateChangedEventArgs
System.Windows.Forms.DataGridViewEditingControlShowingEventArgs
System.Windows.Forms.DataGridViewRowContextMenuStripNeededEventArgs
System.Windows.Forms.DataGridViewRowErrorTextNeededEventArgs
System.Windows.Forms.DataGridViewRowEventArgs
System.Windows.Forms.DataGridViewRowHeightInfoNeededEventArgs
System.Windows.Forms.DataGridViewRowPostPaintEventArgs
System.Windows.Forms.DataGridViewRowsAddedEventArgs
System.Windows.Forms.DataGridViewRowsRemovedEventArgs
System.Windows.Forms.DataGridViewRowStateChangedEventArgs
System.Windows.Forms.DateBoldEventArgs
System.Windows.Forms.DateRangeEventArgs
System.Windows.Forms.Design.Behavior.BehaviorDragDropEventArgs
System.Windows.Forms.DragEventArgs
System.Windows.Forms.DrawItemEventArgs
System.Windows.Forms.DrawListViewColumnHeaderEventArgs
System.Windows.Forms.DrawListViewItemEventArgs
System.Windows.Forms.DrawListViewSubItemEventArgs
System.Windows.Forms.DrawToolTipEventArgs
System.Windows.Forms.DrawTreeNodeEventArgs
System.Windows.Forms.FormClosedEventArgs
System.Windows.Forms.GiveFeedbackEventArgs
System.Windows.Forms.HelpEventArgs
System.Windows.Forms.HtmlElementErrorEventArgs
System.Windows.Forms.HtmlElementEventArgs
System.Windows.Forms.InputLanguageChangedEventArgs
System.Windows.Forms.Integration.ChildChangedEventArgs
System.Windows.Forms.Integration.IntegrationExceptionEventArgs
System.Windows.Forms.InvalidateEventArgs
System.Windows.Forms.ItemChangedEventArgs
System.Windows.Forms.ItemCheckedEventArgs
System.Windows.Forms.ItemCheckEventArgs
System.Windows.Forms.ItemDragEventArgs
System.Windows.Forms.KeyEventArgs
System.Windows.Forms.KeyPressEventArgs
System.Windows.Forms.LabelEditEventArgs
System.Windows.Forms.LayoutEventArgs
System.Windows.Forms.LinkClickedEventArgs
System.Windows.Forms.LinkLabelLinkClickedEventArgs
System.Windows.Forms.ListViewItemMouseHoverEventArgs
System.Windows.Forms.ListViewItemSelectionChangedEventArgs
System.Windows.Forms.ListViewVirtualItemsSelectionRangeChangedEventArgs
System.Windows.Forms.MaskInputRejectedEventArgs
System.Windows.Forms.MeasureItemEventArgs
System.Windows.Forms.MouseEventArgs
System.Windows.Forms.NavigateEventArgs
System.Windows.Forms.NodeLabelEditEventArgs
System.Windows.Forms.PaintEventArgs
System.Windows.Forms.PreviewKeyDownEventArgs
System.Windows.Forms.PropertyTabChangedEventArgs
System.Windows.Forms.PropertyValueChangedEventArgs
System.Windows.Forms.QueryAccessibilityHelpEventArgs
System.Windows.Forms.QueryContinueDragEventArgs
System.Windows.Forms.QuestionEventArgs
System.Windows.Forms.RetrieveVirtualItemEventArgs
System.Windows.Forms.ScrollEventArgs
System.Windows.Forms.SearchForVirtualItemEventArgs
System.Windows.Forms.SelectedGridItemChangedEventArgs
System.Windows.Forms.SplitterEventArgs
System.Windows.Forms.TabControlEventArgs
System.Windows.Forms.ToolBarButtonClickEventArgs
System.Windows.Forms.ToolStripArrowRenderEventArgs
System.Windows.Forms.ToolStripContentPanelRenderEventArgs
System.Windows.Forms.ToolStripDropDownClosedEventArgs
System.Windows.Forms.ToolStripItemClickedEventArgs
System.Windows.Forms.ToolStripItemEventArgs
System.Windows.Forms.ToolStripItemRenderEventArgs
System.Windows.Forms.ToolStripPanelRenderEventArgs
System.Windows.Forms.ToolStripRenderEventArgs
System.Windows.Forms.TreeNodeMouseHoverEventArgs
System.Windows.Forms.TreeViewEventArgs
System.Windows.Forms.TypeValidationEventArgs
System.Windows.Forms.UICuesEventArgs
System.Windows.Forms.UpDownEventArgs
System.Windows.Forms.WebBrowserDocumentCompletedEventArgs
System.Windows.Forms.WebBrowserNavigatedEventArgs
System.Windows.Forms.WebBrowserProgressChangedEventArgs
System.Windows.Ink.DrawingAttributesReplacedEventArgs
System.Windows.Ink.LassoSelectionChangedEventArgs
System.Windows.Ink.PropertyDataChangedEventArgs
System.Windows.Ink.StrokeCollectionChangedEventArgs
System.Windows.Ink.StrokeHitEventArgs
System.Windows.Ink.StylusPointsReplacedEventArgs
System.Windows.Input.AccessKeyEventArgs
System.Windows.Input.InputLanguageEventArgs
System.Windows.Input.InputMethodStateChangedEventArgs
System.Windows.Input.NotifyInputEventArgs
System.Windows.Markup.Localizer.BamlLocalizerErrorNotifyEventArgs
System.Windows.Media.ExceptionEventArgs
System.Windows.Media.Imaging.DownloadProgressEventArgs
System.Windows.Media.MediaScriptCommandEventArgs
System.Windows.Media.RenderingEventArgs
System.Windows.Navigation.FragmentNavigationEventArgs
System.Windows.Navigation.NavigationEventArgs
System.Windows.Navigation.NavigationFailedEventArgs
System.Windows.Navigation.NavigationProgressEventArgs
System.Windows.Navigation.ReturnEventArgs(Of T)
System.Windows.RoutedEventArgs
System.Windows.StartupEventArgs
System.Windows.Threading.DispatcherEventArgs
System.Windows.Threading.DispatcherHookEventArgs
System.Windows.Xps.Packaging.PackagingProgressEventArgs
System.Windows.Xps.Serialization.XpsSerializationPrintTicketRequiredEventArgs
System.Workflow.Activities.ConditionalEventArgs
System.Workflow.Activities.ExternalDataEventArgs
System.Workflow.Activities.InvokeWebServiceEventArgs
System.Workflow.Activities.OperationValidationEventArgs
System.Workflow.Activities.ReplicatorChildEventArgs
System.Workflow.Activities.SendActivityEventArgs
System.Workflow.Activities.SetStateEventArgs
System.Workflow.ComponentModel.ActivityCollectionChangeEventArgs
System.Workflow.ComponentModel.ActivityExecutionStatusChangedEventArgs
System.Workflow.ComponentModel.Design.ActivityChangedEventArgs
System.Workflow.ComponentModel.Design.ActivityDesignerLayoutEventArgs
System.Workflow.ComponentModel.Design.ActivityDesignerPaintEventArgs
System.Workflow.ComponentModel.Design.ActivityDesignerResizeEventArgs
System.Workflow.ComponentModel.Design.ConnectorEventArgs
System.Workflow.ComponentModel.QueueEventArgs
System.Workflow.Runtime.CorrelationTokenEventArgs
System.Workflow.Runtime.ServicesExceptionNotHandledEventArgs
System.Workflow.Runtime.Tracking.ProfileRemovedEventArgs
System.Workflow.Runtime.Tracking.ProfileUpdatedEventArgs
System.Workflow.Runtime.Tracking.TrackingWorkflowChangedEventArgs
System.Workflow.Runtime.Tracking.TrackingWorkflowExceptionEventArgs
System.Workflow.Runtime.Tracking.TrackingWorkflowSuspendedEventArgs
System.Workflow.Runtime.Tracking.TrackingWorkflowTerminatedEventArgs
System.Workflow.Runtime.WorkflowEventArgs
System.Workflow.Runtime.WorkflowRuntimeEventArgs
System.Xml.Linq.XObjectChangeEventArgs
System.Xml.Schema.ValidationEventArgs
System.Xml.Serialization.UnreferencedObjectEventArgs
System.Xml.Serialization.XmlAttributeEventArgs
System.Xml.Serialization.XmlElementEventArgs
System.Xml.Serialization.XmlNodeEventArgs
System.Xml.XmlNodeChangedEventArgs
System.Xml.Xsl.XsltMessageEncounteredEventArgs
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The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.