android - Start Fragment from Activity -

android - Start Fragment from Activity -

i'm able start fragment activity. im worried potential problems implementation.

i have 2 fragments, fragmenta , fragmentb , have 3 activity classes, activity1, activity2, resultactivity

public class navigationtabs extends fragmentactivity { @override protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.simple_tabs_2); fragmentstatepageradapter adapter = new mytabs(getsupportfragmentmanager()); .... .... } static class mytabs extends fragmentstatepageradapter { public mytabs(fragmentmanager fm) { super(fm); } @override public fragment getitem(int position) { switch(position) { case 0: fragmenta fraga = new fragmenta(); homecoming fraga; case 1: fragmentb fragb = new fragmentb(); homecoming fragb; ...... ...... } }

^how phone call fragmenta , fragmentb

fragmenta starts activity1 via intent.

intent intent = new intent(getactivity(), activity1.class); startactivity(intent);

activity1 passes results of counter resultactivity

resultactivity starts(or returns to) fragmenta , sets sharedpreferences via onclick this

public void onclick(view v) { if(v.getid()== r.id.button_1){ sharedpreferences sp = preferencemanager.getdefaultsharedpreferences(this); editor edit = sp.edit(); edit.putint(passedsavepref, counter); edit.commit(); finish(); } }

fragmentb starts activity2 via intent.

intent intent = new intent(getactivity(), activity2.class); startactivity(intent);

activity2 passes results of counter resultactivity

resultactivity starts(returns to) fragmentb , sets sharedpreferences via onclick this

public void onclick(view v) { if(v.getid()== r.id.button_1){ sharedpreferences sp = preferencemanager.getdefaultsharedpreferences(this); editor edit = sp.edit(); edit.putint(passedsavepref, counter); edit.commit(); finish(); } }

this works needs. gc seems fine, freeing , allocating memory.

resultactivty returns right fragment, , sets savedpreferences correctly.

yet seems bad implementation. starters, while searching through other questions i've read, "don't start activity straight fragment" poster linked proper implementation here https://developer.android.com/guide/components/fragments.html#eventcallbacks

i've tried calling activity1 fragmenta this, don't see difference in behavior or performance

intent intent = new intent(getactivity(), activity1.class); startactivity(intent); getactivity().getsupportfragmentmanager().popbackstack();

so question is, need finish/remove fragmenta when start activity1, start fragmenta 1 time again resultactivityusing like

fragmenttransaction transaction = getfragmentmanager().begintransaction();

thanks in advance.

edit trying either kill/finish/pop fragmenta re-start resultactivity. reason tying because savedpreferences not loading when going fragmenta resultactivity.(well saving , loading correctly, couldn't see them)

as understand docs,fragments go on pause. calling loadpreferences method onresume(); loaded savedpreferences.

not marking answer, because did not implement of standard/proper practices of dealing fragments popbackstack(); fragmenttransactions etc

quote: "don't start activity straight fragment"

i read poster wrote this, , disagree. rationale reduces modularity of fragment, , believes should impelment interface phone call activity.

i disagree. doesn't cut down modularity, in fact increases it. why implement layer of abstraction fragment intended in every implementation? why re-write same code in every activity, when can modularized in fragment? in fact fragments wouldn't have own specialized functions starting activities if against design principles.

for instance, if start activity using fragment.startacitivtyforresult(), fragment set straight onactivityresult receiver. not if utilize activity instance straight start new activity.

you not need remove framgents before starting new activity

android pause/stop fragments, , potentially destroy them , underlying activity if need be. android destroying , recreating activities , fragments, every time alter orientation on screen - default settings has activity , fragments commit mass suicide.

this why functions onsaveinstancestate() important, because allow activities , fragments homecoming saved state. general rule of android programming activity / fragments should able respond spontaneous death gracefully.

android android-intent android-fragments fragmenttransaction