How to avoid non-default constructors in fragments?

Question

I'm currently working on an android app, and it suddenly gave me these errors (it used to work like this, which is the strange part):

Avoid non-default constructors in fragments: use a default constructor plus Fragment#setArguments(Bundle) instead

and

This fragment should provide a default constructor (a public constructor with no arguments)

This is the code:

public DatePickerFragment(ProjectOverviewFragment list){
    this.list = list;
    Calendar cal = Calendar.getInstance();

    date = cal.get(Calendar.DAY_OF_MONTH)+"-"+cal.get(Calendar.MONTH)+"-"+cal.get(Calendar.YEAR);
}

Add default constructor without arguments as: `public DatePickerFragment(){}` — My God, Jul 02 '13 at 09:36
I added a default constructor without arguments, which seems fine. But it stil gives the same error about the constructor that does take argument. — , Jul 02 '13 at 09:49
They are lint errors, which explains the "it used to work like this, which is the strange part". By default lint is only run on files you've modified, and you can clear lint warnings/errors yourself and still have a project that builds and works to some degree. Still it is a good idea to fix the underlying issues causing lint to emit errors. They are there for good reasons. — laalto, Jul 14 '13 at 08:36
@laalto how to disable this particular link check in Android Studio 1.2? — Shajeel Afzal, May 05 '15 at 03:19

score 4 · Answer 1 · edited Apr 07 '14 at 14:41

You have to call fragment something like this:

    int id;

    Fragment newFragment = CountingFragment.newInstance(id);
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    ft.replace(R.id.simple_fragment, newFragment);
    ft.addToBackStack(null);
    ft.commit();

    public static class CountingFragment extends Fragment {
    int mNum;

    static CountingFragment newInstance(int num) {
        CountingFragment f = new CountingFragment();
        Bundle args = new Bundle();
        args.putInt("num", num);
        f.setArguments(args);

        return f;
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mNum = getArguments() != null ? getArguments().getInt("num") : 1;
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment, container, false);
        View tv = v.findViewById(R.id.text);
        ((TextView)tv).setText("Hello. This is fragment example #" + mNum);
             tv.setBackgroundDrawable(getResources().getDrawable(android.R.drawable.gallery_thumb));
        return v;
    }
}

How to avoid non-default constructors in fragments?

1 Answers1