Attempt to invoke virtual method ' 'on a null object reference

Question

I am getting the following error

Attempt to invoke virtual method \'void android.widget.StackView.setAdapter(android.widget.Adapter)\' on a null

Answer 1

You are doing:

stackView = (StackView) getActivity().findViewById(R.id.stackView1);

Your stackView is null. getActivity().findViewById returns null.

Why are you using getActivity()?

Where is the stackView? You should load it from the right xml.

as @Tauqir mentioned, you need to inflate the right xml like this:

View view = inflater.inflate(R.layout.events_layout, null);
stackView = (StackView) view.findViewById(R.id.stackView1);
return view;

Answer 2

R.id.stackView1 is not found when you try to assign stackView, so it is null

Answer 3

Try this inside onCreateView

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.events_layout, null);

        -------------some codes ------------

        stackView = (StackView) view.findViewById(R.id.stackView1);

        -------------some codes ------------
        return view;

    }

Answer 4

Do this

View rootView = inflater.inflate(R.layout.events, container, false);
stackView = (StackView) rootview.findViewById(R.id.stackView1);
.
.
.
return rootview

You first need to inflate the layout and call findViewById() on the View it returns, thus getActivity().findViewById should be rootView.findViewByID.

There are some other issues with your code as well. Like getctivity().getApplicationContext, just getActivity() is fine.

Answer 5

change container and false to null

Do this:

View rootView = inflater.inflate(R.layout.events, null);