java - Persisting fragment state -

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i have frame layout in activity want display different fragments inside. have sliding drawer 3 options, each of lead fragment being loaded inside frame layout. use following accomplish this:

fragment nextfragment = determinefragmenttoswitchto(nextfragmenttag); transaction.replace(r.id.fragment_container, nextfragment);

the first method determines fragment need evaluating nextfragmenttag string , loading new fragment so:

if (fragmenttag.equals(constants.studentpage))      nextfragment = new studentfragment(); else if (fragmenttag.equals(constants.teacherpage))      nextfragment = new teacherfragment(); else if (fragmenttag.equals(constants.parentpage))      nextfragment = new parentfragment();

clearly approach creating new fragment each time , running through whole fragment lifecycle without saving state. if on student page , scrolling through student list , switch parent page, when go student page, reloads entire list (i fetching server) , looses place in it. how can persist state , sort of cache fragment in manager (if makes sense)?

you use fragmenttransaction's hide(fragment) , show(fragment) methods, e.g.:

// in parent activity   studentfragment studentfragment; teacherfragment teacherfragment; parentfragment parentfragment; fragment fragmentondisplay;  @override protected void oncreate(bundle savedinstancestate) {     // initialize fragmentmanager, fragmenttransaction, etc.     studentfragment = (studentfragment) fragmentmanager.findfragmentbytag(constants.studentpage);    if (studentfragment == null) {       studentfragment = new studentfragment ();       fragmenttransaction.add(r.id.your_frame_layout, studentfragment, constants.studentpage);    }     // repeat same procedure other 2 fragments          // suppose want begin teacherfragment on     // display - in case hide studentfragment ,     // parentfragment:                  fragmenttransaction.hide(studentfragment);    fragmenttransaction.hide(parentfragment);    fragmentondisplay = teacherfragment;    fragmenttransaction.commit(); }

now whenever need switch fragments, hide fragment on display, , show fragment need, e.g.:

... fragmenttransaction.hide(fragmentondisplay); fragmenttransaction.show(parentfragment); fragmentondisplay = parentfragment; fragmenttransaction.commit();

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