ObjectDisposedException Class (System) (original) (raw)
Definition
The exception that is thrown when an operation is performed on a disposed object.
public ref class ObjectDisposedException : InvalidOperationException
public class ObjectDisposedException : InvalidOperationException
[System.Serializable]
public class ObjectDisposedException : InvalidOperationException
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public class ObjectDisposedException : InvalidOperationException
type ObjectDisposedException = class
inherit InvalidOperationException
[<System.Serializable>]
type ObjectDisposedException = class
inherit InvalidOperationException
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type ObjectDisposedException = class
inherit InvalidOperationException
Public Class ObjectDisposedException
Inherits InvalidOperationException
Inheritance
Inheritance
Attributes
Examples
The following example demonstrates an error that causes the ObjectDisposedException
exception to be thrown.
using System;
using System.IO;
public class ObjectDisposedExceptionTest
{
public static void Main()
{
MemoryStream ms = new MemoryStream(16);
ms.Close();
try
{
ms.ReadByte();
}
catch (ObjectDisposedException e)
{
Console.WriteLine("Caught: {0}", e.Message);
}
}
}
open System
open System.IO
let ms = new MemoryStream 16
ms.Close()
try
ms.ReadByte()
|> ignore
with :? ObjectDisposedException as e ->
printfn $"Caught: {e.Message}"
Imports System.IO
Public Class ObjectDisposedExceptionTest
Public Shared Sub Main()
Dim ms As New MemoryStream(16)
ms.Close()
Try
ms.ReadByte()
Catch e As ObjectDisposedException
Console.WriteLine("Caught: {0}", e.Message)
End Try
End Sub
End Class
This code produces the following output:
Caught:
Cannot access a closed Stream.
An ObjectDisposedException is thrown when you try to access a member of an object that implements the IDisposable interface or IAsyncDisposable interface, and that object has been disposed. Typically, this exception is caused by one of the following conditions:
- You've called an
IDisposable
object'sDispose
method (or anIDisposableAsync
object'sDisposeAsync
method), and you're trying to access an instance member that gets or sets the object's state. The following example illustrates the ObjectDisposedException that is thrown when you try to reset the frequency of timer notifications after you call the Timer.Dispose method.
using System;
using System.Threading;
public class Example
{
public static void Main()
{
Timer t = new Timer(TimerNotification, null,
100, Timeout.Infinite);
Thread.Sleep(2000);
t.Dispose();
t.Change(200, 1000);
Thread.Sleep(3000);
}
private static void TimerNotification(Object obj)
{
Console.WriteLine("Timer event fired at {0:F}", DateTime.Now);
}
}
// The example displays output like the following:
// Timer event fired at Monday, July 14, 2014 11:54:08 AM
//
// Unhandled Exception: System.ObjectDisposedException: Cannot access a disposed object.
// at System.Threading.TimerQueueTimer.Change(UInt32 dueTime, UInt32 period)
// at Example.Main()
open System
open System.Threading
let timerNotification _ =
printfn $"Timer event fired at {DateTime.Now:F}"
let t = new Timer(timerNotification, null, 100, Timeout.Infinite)
Thread.Sleep 2000
t.Dispose()
t.Change(200, 1000)
|> ignore
Thread.Sleep 3000
// The example displays output like the following:
// Timer event fired at Monday, July 14, 2014 11:54:08 AM
//
// Unhandled Exception: System.ObjectDisposedException: Cannot access a disposed object.
// at System.Threading.TimerQueueTimer.Change(UInt32 dueTime, UInt32 period)
// at <StartupCode$fs>.main()
Imports System.Threading
Module Example
Public Sub Main()
Dim t As New Timer(AddressOf TimerNotification, Nothing,
100, Timeout.Infinite)
Thread.Sleep(2000)
t.Dispose()
t.Change(200, 1000)
Thread.Sleep(3000)
End Sub
Private Sub TimerNotification(obj As Object)
Console.WriteLine("Timer event fired at {0:F}", Date.Now)
End Sub
End Module
' The example displays output like the following:
' Timer event fired at Monday, July 14, 2014 11:54:08 AM
'
' Unhandled Exception: System.ObjectDisposedException: Cannot access a disposed object.
' at System.Threading.TimerQueueTimer.Change(UInt32 dueTime, UInt32 period)
' at Example.Main()
- You've called an object's
Close
method, and you're trying to access an instance member that gets or sets the object's state. Often, theClose
method provides a type's public implementation of the IDisposable.Dispose method. The same is true forCloseAsync
and<xref:System.IAsyncDisposable.DisposeAsync%2A?displayProperty=nameWithType>
. - You've called an object's
Dispose
orDisposeAsync
methods multiple times. Typically, this doesn't throw an exception. However, depending on how a type implements IDisposable.Dispose or IAsyncDisposable.DisposeAsync, it may not allow multiple calls to that method.
In most cases, this exception results from developer error. Instead of handling the error in a try
/catch
block, you should correct the error, typically by reinstantiating the object.