Question

I understand mostly everything in this code, except when newIstance() is being used. Could anyone please explain. Much appreciated.

public class DateDialogFragment extends DialogFragment {

public static String TAG = "DateDialogFragment";

static Context sContext;
static Calendar sDate;
static DateDialogFragmentListener sListener;

public static DateDialogFragment newInstance(Context context, int titleResource, Calendar date){
    DateDialogFragment dialog  = new DateDialogFragment();

sContext = context;
    sDate = date;

Bundle args = new Bundle();
args.putInt("title", titleResource);
dialog.setArguments(args);
return dialog;
   }
}

I made an edit, I guess its working differently when its static. I assume thats why I am confused. How is the method changed when its static? I don’t really see why not do it in the constructor?

Answer 1

When using fragments (any class that extends Fragment) you frequently need to pass some data. That’s achieved by using the setArguments method which receives a Bundle. Since doing so requires a lot of code (create the bundle, take into account key names, etc.), it is common to pass the data to a static method (usually called newInstance). The idea of that method is to create the arguments bundle and pass it to the Fragment; then it returns the fragment and you can put it where ever you want.

Another advantage of using fragments that way is that when you are inserting a fragment directly in an XML layout, there must be an empty constructor (or nothing at all). If you create a fragment with a constructor (to pass its necessary data) you could get some errors regarding the missing empty constructor.