android - Firebase Database Exception -

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• android save object in firebase 1 answer

here class intend read location type data item firebase database , store in location type object. tried store datasnapshot in object of class had location type argument in constructor, got same error saying :

" com.google.firebase.database.databaseexception: class android.location.location missing constructor no arguments"

package com.example.aadi.sarthi_; import android.content.context; import android.content.intent; import android.location.location; import android.os.bundle; import android.support.annotation.nullable; import android.support.v4.app.fragment; import android.support.v7.widget.linearlayoutmanager; import android.support.v7.widget.recyclerview; import android.util.log; import android.view.layoutinflater; import android.view.menuitem; import android.view.view; import android.view.viewgroup; import com.google.firebase.database.childeventlistener; import com.google.firebase.database.datasnapshot; import com.google.firebase.database.databaseerror; import com.google.firebase.database.databasereference; import com.google.firebase.database.firebasedatabase; import com.google.firebase.database.valueeventlistener;  import java.util.arraylist; import java.util.list;   public class activenotifications extends fragment{     public static final string notification_msg = "notification msg";     public recyclerview recyclerview;      string user_mac;     public list<notifylistrowitem> result;     public useradapter useradapter; private     databasereference reference = firebasedatabase.getinstance().getreference(); private     databasereference eventref = reference.child("events");      // create intent send notification     public static intent makenotificationintent(context context, string msg) {         intent intent = new intent( context, activenotifications.class );         intent.putextra( notification_msg, msg );         return intent;     }      @nullable     @override     public view oncreateview(layoutinflater inflater, @nullable viewgroup container, @nullable bundle savedinstancestate) {         view view =  inflater.inflate(r.layout.activity_active_notifications, container, false);         getmac();         result = new arraylist<>();         recyclerview = (recyclerview) view.findviewbyid(r.id.notification_list);         recyclerview.sethasfixedsize(true);         linearlayoutmanager rlm = new linearlayoutmanager(getactivity());         rlm.setorientation(linearlayoutmanager.vertical);          recyclerview.setlayoutmanager(rlm);         /*         createnotifylistrowitem();*/         useradapter = new useradapter(result);         recyclerview.setadapter(useradapter);         updatelist();         return view;     }     @override     public boolean oncontextitemselected(menuitem item) {          switch (item.getitemid()){             case 0:                 break;             case 1:                 break;         }          return super.oncontextitemselected(item);     }     public void updatelist(){         final databasereference locationref = reference.child(string.valueof(user_mac)).child("location");         final location userloc = null;         final location eventloc = null;          locationref.addlistenerforsinglevalueevent(new valueeventlistener() {             @override             public void ondatachange(datasnapshot datasnapshot) {                 if(datasnapshot.exists()) {                      location location = datasnapshot.getvalue(location.class);                 userloc.set(location);                  }              }              @override             public void oncancelled(databaseerror databaseerror) {              }         });        eventref.limittofirst(2).addchildeventlistener(new childeventlistener() {             @override             public void onchildadded(datasnapshot datasnapshot, string s) {                 eventref.push().child("location");                 location location = datasnapshot.getvalue(location.class);                 eventloc.set(location);                  if(eventloc.distanceto(userloc)<=1000) {                     result.add(datasnapshot.getvalue(notifylistrowitem.class));                      useradapter.notifydatasetchanged();                  }              }              @override             public void onchildchanged(datasnapshot datasnapshot, string s) {                 log.w("asd", "in onchildchanged");                 notifylistrowitem notifylistrowitem = datasnapshot.getvalue(notifylistrowitem.class);                 int index = getitemindex(notifylistrowitem);                 result.set(index,notifylistrowitem);                 useradapter.notifyitemchanged(index);             }              @override             public void onchildremoved(datasnapshot datasnapshot) {                  log.w("in ", "onchildremoved");                 notifylistrowitem model = datasnapshot.getvalue(notifylistrowitem.class);                 int index = getitemindex(model);                 result.remove(index);                 useradapter.notifyitemremoved(index);              }              @override             public void onchildmoved(datasnapshot datasnapshot, string s) {                 log.w("in", "onchildmoved");             }              @override             public void oncancelled(databaseerror databaseerror) {                 log.w("in", "onchildcancelled");                 return;             }         });     }     private int getitemindex(notifylistrowitem item){         int index = -1;          (int i=0;i<result.size();i++){             if(result.get(i).key.equals(item.key)){                 index = i;                 break;             }         }         return index;     }     protected void getmac(){         gettingmac gettingmac = new gettingmac(getactivity());         user_mac = gettingmac.mac();     } } 

you need have empty constructor location class.

public location () {}