Question

Basically Dialogs inactivates the activity at the background. So the DialogFragment does the same with increased complexity. So why should one go for DialogFragment though various subclasses of Dialog are available.

Answer 1

Fragments are used with in your activity, but to present a fragment as dialog (window) using FragmentTransaction and followup with fragment’s life-cycle, you need to use DialogFragment. However, you may do use simple Dialog too, but then it has nothing to do with the fragment’s life-cycle.

As per google docs:

A DialogFragment can still optionally be used as a normal fragment, if
desired. This is useful if you have a fragment that in some cases
should be shown as a dialog and others embedded in a larger UI.