android - Alarm Manager background services not working properly -

i working on project , making reminder app. made yesterday, problem facing. if destroy app, notification doesn't come anymore. if minimize app, works correctly. if set alarm 4-5 hours longer current time, not works/not shows notification

this main activity

public class setquiz extends appcompatactivity implements     datepickerdialog.ondatesetlistener, timepickerdialog.ontimesetlistener{  toolbar toolbar; edittext title, details; button save, time; textview s_date, s_time;   quizdatabasehelper mydb;  string q_title, q_details, h, m, y, mo, d; int year, month, day, hour, minute; int yearfinal, monthfinal, dayfinal, hourfinal, minutefinal;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_set_quiz);      mydb = new quizdatabasehelper(this);       title = (edittext) findviewbyid(r.id.quiz_title);     details = (edittext) findviewbyid(r.id.quiz_details);     save = (button) findviewbyid(r.id.quiz_save);     time = (button) findviewbyid(r.id.add_time);     s_date = (textview) findviewbyid(r.id.show_date);     s_time = (textview) findviewbyid(r.id.show_time);      calendar c = calendar.getinstance();      string yy = string.valueof(c.get(calendar.year));     string mm = string.valueof(c.get(calendar.month)+1);     string dd = string.valueof(c.get(calendar.day_of_month));       int hh = c.get(calendar.hour);     int mmm = c.get(calendar.minute);      string timeset = "";     if (hh > 12) {         hh -= 12;         timeset = "pm";     } else if (hh == 0) {         hh += 12;         timeset = "am";     } else if (hh == 12){         timeset = "pm";     }else{         timeset = "am";     }      string min = "";     if (mmm < 10)         min = "0" + mmm;     else         min = string.valueof(mmm);      string hhh = string.valueof(hh);     string mmmm = string.valueof(min);      s_date.settext(yy+"-"+mm+"-"+dd);     s_time.settext(hhh+"."+mmmm+" "+timeset);        toolbar = (toolbar) findviewbyid(r.id.toolbar);     setsupportactionbar(toolbar);     getsupportactionbar().setdisplayhomeasupenabled(true);       time.setonclicklistener(new view.onclicklistener() {          @override         public void onclick(view v) {             calendar c = calendar.getinstance();              year = c.get(calendar.year);             month = c.get(calendar.month);             day = c.get(calendar.day_of_month);               datepickerdialog datepickerdialog = new datepickerdialog(setquiz.this,r.style.datepickerdialogtheme,                     setquiz.this, year,month, day);             datepickerdialog.show();         }     });       save.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view v) {              q_title = title.gettext().tostring();             q_details = details.gettext().tostring();              if(q_title.length() == 0 || q_details.length() == 0){                 toast.maketext(getapplicationcontext(), "please fill empty field!",                         toast.length_short).show();              }             else{                 int alarm_id =  mydb.insertdata(q_title, q_details, h, m, y, mo, d);                  if(integer.valueof(m) <=9){                     m = "0"+m;                 }                  // code alarm manager                  calendar calendar2 = calendar.getinstance();                  calendar2.set(calendar.hour_of_day, integer.parseint(h));                 calendar2.set(calendar.minute, integer.parseint(m));                 calendar2.set(calendar.year, integer.parseint(y));                 calendar2.set(calendar.month, integer.parseint(mo)-1);                 calendar2.set(calendar.day_of_month, integer.parseint(d)-1);                   intent intent = new intent(getapplicationcontext(), notificationreceiver.class);                 intent.putextra("id", alarm_id);                  pendingintent pendingintent = pendingintent.getbroadcast(getapplicationcontext(), alarm_id, intent,                         pendingintent.flag_update_current);                  alarmmanager alarmmanager = (alarmmanager) getsystemservice(alarm_service);                  alarmmanager.setrepeating(alarmmanager.rtc_wakeup, calendar2.gettimeinmillis(),                         alarmmanager.interval_fifteen_minutes, pendingintent);                  // code alarm manager finish                  intent intent2 = new intent(setquiz.this, quizreminder.class);                 startactivity(intent2);                 finish();             }           }     });  }  @override public void ondateset(datepicker view, int year, int month, int dayofmonth) {     yearfinal = year;     monthfinal = month + 1;     dayfinal = dayofmonth;      y = string.valueof(yearfinal);     mo = string.valueof(monthfinal);     d = string.valueof(dayfinal);      s_date.settext(d+"-"+mo+"-"+y);      calendar c = calendar.getinstance();      hour = c.get(calendar.hour_of_day);     minute = c.get(calendar.minute);      timepickerdialog timepickerdialog = new timepickerdialog( setquiz.this,             r.style.timepickerdialogtheme, setquiz.this,             hour, minute , false);      timepickerdialog.show(); }  @override public void ontimeset(timepicker view, int hourofday, int minute) {      hourfinal = hourofday;     minutefinal = minute;      h = string.valueof(hourfinal);     m = string.valueof(minutefinal);      string timeset = "";     if (hourfinal > 12) {         hourfinal -= 12;         timeset = "pm";     } else if (hourfinal == 0) {         hourfinal += 12;         timeset = "am";     } else if (hourfinal == 12){         timeset = "pm";     }else{         timeset = "am";     }      string min = "";     if (minutefinal < 10)         min = "0" + minute ;     else         min = string.valueof(minutefinal);      string hh = string.valueof(hourfinal);     string mm = string.valueof(min);      string final_time = hh + ":"+mm+" "+timeset;      s_time.settext(final_time);  }  } 

this receiver class

public class notificationreceiver extends broadcastreceiver{  quizdatabasehelper mydb; string title, details;  @override public void onreceive(context context, intent intent) {      int id= intent.getintextra("id", 1);      mydb = new quizdatabasehelper(context);     cursor data = mydb.getquiztitle(string.valueof(id));      while(data.movetonext()) {         title = data.getstring(1);         details = data.getstring(2);     }       notificationmanager notificationmanager = (notificationmanager)             context.getsystemservice(context.notification_service);      intent repeating_intent = new intent(context, quizreminder.class);     repeating_intent.setflags(intent.flag_activity_clear_top);      pendingintent pendingintent = pendingintent.getactivity(context, id , repeating_intent,             pendingintent.flag_update_current);      android.support.v4.app.notificationcompat.builder builder = new notificationcompat.builder(context)             .setcontentintent(pendingintent)             .setsmallicon(r.drawable.notepad)             .setcontenttitle(" ' "+title+" ' "+" quiz tomorrow")             .setdefaults(android.support.v4.app.notificationcompat.default_sound| notification.default_vibrate)             .setcontenttext("syllabus: "+details)             .setautocancel(true);      notificationmanager.notify(id, builder.build());  }   }