android - Replace fragment in host activity from fragment -

i have container activity has framelayout storing fragment inside it.
example have activity initial framgent login page. theare 2 buttons login , register.
user can click register , in case need change current fragment fragment registration fields.
have idea make host activity implement callback interface , pass activity fragment, , when user clicks register callback method called , host activity replacing fragment.
question if there other better way this, maybe more correclty.
please leave suggestions , how deal problem.thanks

you can replace fragments follows ,

    fragmenttransaction transaction = getfragmentmanager().begintransaction();     transaction.replace(<container id>, new registerfragment());     transaction.commit(); 

//if using support library, make sure use getsupportfragmentmanager()