android - AlertDialog not working in a Fragment -

hello i'm doing app in button pressed , alertdialog window pops timepicker. in fragment appcompatactivity not do.

fragment itself:

public class time_change extends fragment implements  timepickerfragment.timedialoglistener { private static final string dialog_time = "mainactivity.timedialog";  private view v; private button timepickeralertdialog; private imagebutton back;  @override @nullable public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {     v = inflater.inflate(r.layout.pamokos, container, false);      timepickeralertdialog = (button) v.findviewbyid(r.id.alert_dialog_time_picker);      timepickeralertdialog.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view v) {              timepickerfragment dialog = timepickerfragment.newinstance();             dialog.show(getactivity().getfragmentmanager(), "timepickerfragment");         }     });      = (imagebutton) v.findviewbyid(r.id.back_btn1);     back.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view v) {              pamokos fr = new pamokos();             time_change fr2 = new time_change();             android.app.fragmentmanager fragmentmanager = getfragmentmanager();             fragmenttransaction fragmenttransaction = fragmentmanager.begintransaction();             fragmenttransaction.replace(r.id.activity_frag, fr);             fragmenttransaction.remove(fr2);             fragmenttransaction.addtobackstack(null);             fragmenttransaction.commit();         }      });     return v; }  @override public void onfinishdialog(string time) {     toast.maketext(getactivity(), "selected time : " + time, toast.length_short).show(); } } 

but shows error at

dialog.show(getactivity().getfragmentmanager(), "timepickerfragment"); 

saying "cannot resolve method 'show(android.app.fragmentmanager, java.lang.string)'"

full code tutorial https://www.androidtutorialpoint.com/basics/android-alert-dialog-tutorial-working-time-picker-date-picker-list-dialogs/

i'm quite lost.

replace

timepickerfragment dialog = timepickerfragment.newinstance(); dialog.show(getactivity().getfragmentmanager(), "timepickerfragment"); 

with this

 fragmentmanager fm = getactivity().getsupportfragmentmanager();  timepickerfragment dialog = new timepickerfragment ();  dialog.show(fm, "timepickerfragment");