Defines a method to release allocated resources.
Assembly: mscorlib (in mscorlib.dll)
Thetype exposes the following members.
The primary use of this interface is to release unmanaged resources. The garbage collector automatically releases the memory allocated to a managed object when that object is no longer used. However, it is not possible to predict when garbage collection will occur. Furthermore, the garbage collector has no knowledge of unmanaged resources such as window handles, or open files and streams.
Use the Dispose method of this interface to explicitly release unmanaged resources in conjunction with the garbage collector. The consumer of an object can call this method when the object is no longer needed.
It is a version-breaking change to add the interface to an existing class, because it changes the semantics of the class.
C++ programmers should read Destructors and Finalizers in Visual C++. In the .NET Framework version, the C++ compiler provides support for implementing deterministic disposal of resources and does not allow direct implementation of the Dispose method.
IDisposable and the inheritance hierarchy
A base class with subclasses that should be disposable must implement as follows:
It should provide one public non-virtual Dispose method and a protected virtual Dispose(Boolean disposing) method.
The Dispose method must call Dispose(true) and should suppress finalization for performance.
The base type should not include any finalizers.
Subclasses should implement the disposable pattern as follows:
They must override Dispose(Boolean) and call the base class Dispose(Boolean) implementation.
They can provide a finalizer if needed. The finalizer must call Dispose(false).
Calling the IDisposable interface
When calling a class that implements the interface, use the try/finally pattern to make sure that unmanaged resources are disposed of even if an exception interrupts your application.
Note that you can use the using statement (Using in Visual Basic) instead of the try/finally pattern. For more information, see the Using Statement (Visual Basic) documentation or the using Statement (C# Reference) documentation.
The following example demonstrates how to create a resource class that implements the interface.
Imports System Imports System.ComponentModel ' The following example demonstrates how to create ' a resource class that implements the IDisposable interface ' and the IDisposable.Dispose method. Public Class DisposeExample ' A class that implements IDisposable. ' By implementing IDisposable, you are announcing that ' instances of this type allocate scarce resources. Public Class MyResource Implements IDisposable ' Pointer to an external unmanaged resource. Private handle As IntPtr ' Other managed resource this class uses. Private component As component ' Track whether Dispose has been called. Private disposed As Boolean = False ' The class constructor. Public Sub New(ByVal handle As IntPtr) Me.handle = handle End Sub ' Implement IDisposable. ' Do not make this method virtual. ' A derived class should not be able to override this method. Public Overloads Sub Dispose() Implements IDisposable.Dispose Dispose(True) ' This object will be cleaned up by the Dispose method. ' Therefore, you should call GC.SupressFinalize to ' take this object off the finalization queue ' and prevent finalization code for this object ' from executing a second time. GC.SuppressFinalize(Me) End Sub ' Dispose(bool disposing) executes in two distinct scenarios. ' If disposing equals true, the method has been called directly ' or indirectly by a user's code. Managed and unmanaged resources ' can be disposed. ' If disposing equals false, the method has been called by the ' runtime from inside the finalizer and you should not reference ' other objects. Only unmanaged resources can be disposed. Protected Overridable Overloads Sub Dispose(ByVal disposing As Boolean) ' Check to see if Dispose has already been called. If Not Me.disposed Then ' If disposing equals true, dispose all managed ' and unmanaged resources. If disposing Then ' Dispose managed resources. component.Dispose() End If ' Call the appropriate methods to clean up ' unmanaged resources here. ' If disposing is false, ' only the following code is executed. CloseHandle(handle) handle = IntPtr.Zero ' Note disposing has been done. disposed = True End If End Sub ' Use interop to call the method necessary ' to clean up the unmanaged resource. <System.Runtime.InteropServices.DllImport("Kernel32")> _ Private Shared Function CloseHandle(ByVal handle As IntPtr) As [Boolean] End Function ' This finalizer will run only if the Dispose method ' does not get called. ' It gives your base class the opportunity to finalize. ' Do not provide finalize methods in types derived from this class. Protected Overrides Sub Finalize() ' Do not re-create Dispose clean-up code here. ' Calling Dispose(false) is optimal in terms of ' readability and maintainability. Dispose(False) MyBase.Finalize() End Sub End Class Public Shared Sub Main() ' Insert code here to create ' and use the MyResource object. End Sub End Class
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.