Hi!

I have a class that derives from TreeNode. I've got a wierd NullPointerException from the Invoke method of the TreeView until I discovered that I had to add "new object()" to the Invoke call. Here is my code:


If I remove the "new object()" parameter, the Invoke method throws a NullPointerException. If I add the parameter, the delegate is called correctly.

I just wrote this if someone has the same troubles!

Regards

Hi, confused1982,

Based on my understanding, when you invoke a method of your TreeView without the paramter part, you will get a NullPointerException, right?

Well,I am afraid that this is not a bug/issue with TreeView.

Because your InternalLoadHandlerContentsUI method has an object parameter, so you will need to pass a parameter to the delegate.

Please read this article

http://msdn2.microsoft.com/en-us/library/a1hetckb(VS.80).aspx

"method

A delegate to a method that takes parameters of the same number and type that are contained in the args parameter. "

As you are using aWaitCallBack to create the delegate, if you remove the new object(), it will lose the parameter and give you a NullPointerException.

Maybe this sample will give you a more clear concept.

Hi, confused1982,

Based on my understanding, when you invoke a method of your TreeView without the paramter part, you will get a NullPointerException, right?

Well,I am afraid that this is not a bug/issue with TreeView.

Because your InternalLoadHandlerContentsUI method has an object parameter, so you will need to pass a parameter to the delegate.

Please read this article

http://msdn2.microsoft.com/en-us/library/a1hetckb(VS.80).aspx

"method

A delegate to a method that takes parameters of the same number and type that are contained in the args parameter. "

As you are using aWaitCallBack to create the delegate, if you remove the new object(), it will lose the parameter and give you a NullPointerException.

Maybe this sample will give you a more clear concept.

You can use google to search for other answers