I have an app where save data and retrieve also but the problem is when I saving those data , some of those data saved successfully but some others not so it got crushed for the onDataChange method as it found data is changing but can not find some of others.


private void SaveIntoFirebase()
{
DatabaseReference reference= FirebaseDatabase.getInstance().getReference().child(DBConst.AppointmentShedule).child("01"/*FirebaseAuth.getInstance().getCurrentUser().getUid()*/).child(HospitalNameEt.getText().toString());
        reference.child(DBConst.AvailableDay).setValue(SelectDayTv.getText().toString());
        reference.child(DBConst.AppointmentTime).setValue(StartingTimeEt.getText().toString()+"~"+EndingTimeEt.getText().toString());
        reference.child(DBConst.UnavaiableSDate).setValue(StaringDateEt.getText().toString());
        reference.child(DBConst.UnavaiableEDate).setValue(EndingDateEt.getText().toString())
                .addOnCompleteListener(new OnCompleteListener<Void>() {
                    @Override
                    public void onComplete(@NonNull Task<Void> task)
                    {
                        if (task.isComplete())
                        {
                            SaveIntoHospitalDirectory();
                        }
                    }
                });

String HospitalName=dataSnapshot1.getKey();
                        String AvaialableDay=dataSnapshot.child(HospitalName).child(DBConst.AvailableDay).getValue().toString();
                        String AppointmentTime=dataSnapshot.child(HospitalName).child(DBConst.AppointmentTime).getValue().toString();
                        String UnavaiableSDate=dataSnapshot.child(HospitalName).child(DBConst.UnavaiableSDate).getValue().toString();
                        String UnavaiableEDate=dataSnapshot.child(HospitalName).child(DBConst.UnavaiableEDate).getValue().toString();
                        arrayList.add(new AppointmentDataModel("01"/*UID*/,HospitalName,AvaialableDay,AppointmentTime,UnavaiableSDate,UnavaiableEDate));


                        AppointmentDataModel dataModel=dataSnapshot1.getValue(AppointmentDataModel.class);
                        arrayList.add(dataModel);
                    }
                    adapter=new AppointmentDataAdapter(activity,arrayList);
                    listView.setAdapter(adapter);
                }
            }