Defines a method to release allocated unmanaged resources.

For a list of all members of this type, see IDisposable Members.

[Visual Basic]
Public Interface IDisposable
[C#]
public interface IDisposable
[C++]
public __gc __interface IDisposable
[JScript]
public interface IDisposable

Classes that Implement IDisposable

Remarks

The garbage collector automatically releases the memory allocated to a managed object when that object is no longer used, however, it is unpredictable when garbage collection will occur. Furthermore, the garbage collector has no knowledge of unmanaged resources such as window handles, and 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 IDisposable interface to an existing class, as it changes the semantics of the class.

For a detailed discussion about how this interface and the Object.Finalize method are used, see the Programming for Garbage Collection and Implementing a Dispose Method topics.

Example

[Visual Basic] 
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.
      Private 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
         End If
         disposed = True
      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

[C#] 
using System;
using 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 base class that implements IDisposable.
    // By implementing IDisposable, you are announcing that 
    // instances of this type allocate scarce resources.
    public class MyResource: IDisposable
    {
        // Pointer to an external unmanaged resource.
        private IntPtr handle;
        // Other managed resource this class uses.
        private Component component = new Component();
        // Track whether Dispose has been called.
        private bool disposed = false;

        // The class constructor.
        public MyResource(IntPtr handle)
        {
            this.handle = handle;
        }

        // Implement IDisposable.
        // Do not make this method virtual.
        // A derived class should not be able to override this method.
        public void 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(this);
        }

        // 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.
        private void Dispose(bool disposing)
        {
            // Check to see if Dispose has already been called.
            if(!this.disposed)
            {
                // If disposing equals true, dispose all managed 
                // and unmanaged resources.
                if(disposing)
                {
                // Dispose managed resources.
                component.Dispose();
                }
             
                // 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;            
            }
            disposed = true;         
        }

        // Use interop to call the method necessary  
        // to clean up the unmanaged resource.
        [System.Runtime.InteropServices.DllImport("Kernel32")]
        private extern static Boolean CloseHandle(IntPtr handle);

        // Use C# destructor syntax for finalization code.
        // This destructor will run only if the Dispose method 
        // does not get called.
        // It gives your base class the opportunity to finalize.
        // Do not provide destructors in types derived from this class.
        ~MyResource()      
        {
            // Do not re-create Dispose clean-up code here.
            // Calling Dispose(false) is optimal in terms of
            // readability and maintainability.
            Dispose(false);
        }
    }
    public static void Main()
    {
        // Insert code here to create
        // and use the MyResource object.   
    }
}

[C++] 
#using <mscorlib.dll>
#using <System.dll>

using namespace System;
using namespace System::ComponentModel;

// The following example demonstrates how to create
// a resource class that implements the IDisposable interface
// and the IDisposable.Dispose method.

// A base class that implements IDisposable.
// By implementing IDisposable, you are announcing that
// instances of this type allocate scarce resources.
public __gc class MyResource : public IDisposable {
   // Pointer to an external unmanaged resource.
   IntPtr  handle;
   // Other managed resource this class uses.
   Component*  component;
   // Track whether Dispose has been called.
   bool disposed;
public:
   // The class constructor.
   MyResource(IntPtr handle) {
      this->handle = handle;
      disposed = false;
   }

   // Implement IDisposable*
   // Do not make this method virtual.
   // A derived class should not be able to  this method.
   void 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(this);
   }

private:
   // 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.
   void Dispose(bool disposing) {
      // Check to see if Dispose has already been called.
      if (!this->disposed) {
         // If disposing equals true, dispose all managed
         // and unmanaged resources.
         if (disposing) {
            // Dispose managed resources.
            component->Dispose();
         }

         // 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;
      }
      disposed = true;
   }

   // Use interop to call the method necessary
   // to clean up the unmanaged resource.
   [System::Runtime::InteropServices::DllImport(S"Kernel32")]
   static Boolean CloseHandle(IntPtr handle);

   // Use C# destructor syntax for finalization code.
   // This destructor will run only if the Dispose method
   // does not get called.
   // It gives your base class the opportunity to finalize.
   // Do not provide destructors in types derived from this class.
   ~MyResource() {
      // Do not re-create Dispose clean-up code here.
      // Calling Dispose(false) is optimal in terms of
      // readability and maintainability.
      Dispose(false);
   }
};

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button in the upper-left corner of the page.

Requirements

Namespace: System

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: Mscorlib (in Mscorlib.dll)

See Also

IDisposable Members | System Namespace