How to: Make an Object Variable Not Refer to Any Instance
You can disassociate an object variable from any object instance by setting it to Nothing (Visual Basic).
To disassociate an object variable from any object instance
Set the variable to Nothing in an assignment statement.
' Assume account is a defined class Dim currentAccount As account currentAccount = Nothing
Robust Programming
If your code tries to access a member of an object variable that has been set to Nothing, a NullReferenceException occurs. If you set an object variable to Nothing frequently, or if it is possible the variable is not initialized, it is a good idea to enclose member accesses in a Try...Catch...Finally block.
Security
If you use an object variable for objects that contain confidential or sensitive data, you can set the variable to Nothing when you are not actively dealing with one of those objects. This reduces the chance of malicious code gaining access to the data.
See Also
Concepts
Object Variables in Visual Basic