I'm developing an android app and I have a fragment that contains TextView & ListView in it. The list view has custom list items that contains two buttons. I want to make 'onClickListener' for one of those two buttons in my custom adapter class to change the text of the TextView, but I can't access it by findViewById() every time I try I got null exception.
My guess is that you're trying to access the TextView from inside of the Adapter.
If so, then you won't be able to get the TextView and it's normal to get a nullpointer exception.
The findViewById inside your adapter only finds the views that you have inflated in the getView() method of your adapter.
What you can do here is probably use an interface that's implemented by your Fragment to pass the information from your adapter back to the fragment.
This answer might be a good starting point : How to create interface between Fragment and adapter?