Why is my context in my Fragment null?

When are you instantiating your Helper class? Make sure it's after onActivityCreated() in the lifecycle of the Fragment.

http://developer.android.com/images/fragment_lifecycle.png

The following code should work:

@Override
  public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    helper = new Helper(getActivity());
  }

You're attempting to get a Context when the Fragment is first instantiated. At that time, it is NOT attached to an Activity, so there is no valid Context.

Have a look at the Fragment Lifecycle. Everything between onAttach() to onDetach() contain a reference to a valid Context instance. This Context instance is usually retrieved via getActivity()

Code example:

private Helper mHelper;

@Override
public void onAttach(Activity activity){
   super.onAttach (activity);
   mHelper = new Helper (activity);
}

I used onAttach() in my example, @LaurenceDawson used onActivityCreated(). Note the differences. Since onAttach() gets an Activity passed to it already, I didn't use getActivity(). Instead I used the argument passed. For all other methods in the lifecycle, you will have to use getActivity().