Firebase returns wrong values when addValueEventListener called

Question

I have a database on Firebase and are trying to get android to print it into a ListView. I can get the ListView to print something, but it seems like it's some ID's of the values, rather than the actual values. The point is to be able to make a search bar, which can find any data on the database. I have some commented code down in the addValueEventListener. This code should work, but when I use it, my app crashes without an error when I go to the "ExistingCustomerActivity" activity. My database structure and the output from the app, with the current code. Be aware the ListView currently prints the values just under "Buyers". Is there anyone who can help with this issue? Thanks in advance. Update: I can see the data are loaded correctly in the log, but it still displays some kind of ID I assume.

public class ExistingCustomerActivity extends AppCompatActivity {

        private DatabaseReference mDatabaseReference;
        private ListView mUserList;

        private ArrayList<Buyers> mUsernames = new ArrayList<>();

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_existing_customer);

            mDatabaseReference = FirebaseDatabase.getInstance().getReference("Buyers");

            mUserList = (ListView) findViewById(R.id.UserListView);

            final ArrayAdapter<Buyers> arrayAdapter = new ArrayAdapter<Buyers>(this, android.R.layout.simple_list_item_1, mUsernames);

            mUserList.setAdapter(arrayAdapter);

            mDatabaseReference.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    //Buyers buyerList = new Buyers(childSnapshot);

                        for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
                        Map<String, String> map = (Map<String, String>) childSnapshot.getValue();
                        Log.v("YourValue,","Map value is:" +map.toString());
                        Buyers buyerList = new Buyers(map);
                        mUsernames.add(buyerList);

                    }
                    arrayAdapter.notifyDataSetChanged();

                }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
        }
    }

Buyers class:

public class Buyers {
    private String car_Value;
    private String interest;
    private String driverLicenseNr;
    private String name;
    private String personNr;
    private String phone_Number;

public Buyers(Map<String,String> map){
    car_Value = map.get("Bil");
    interest = map.get("Interresse");
    driverLicenseNr = map.get("Kørekortnr");
    name = map.get("Navn");
    personNr = map.get("Personnr");
    phone_Number = map.get("Telefonnr");
}

Answer 1

You need to change your Buyers class variable according to firebase DB structure or use Map to get the values

Try below code to get values using Map from Buyers

mDatabaseReference.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        //Buyers buyerList = new Buyers(childSnapshot);
        for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
            Map<String,String> map=(Map<String, String>) childSnapshot.getValue();
            Buyers buyerList = new Buyers(map);
            mUsernames.add(buyerList);
        }
        arrayAdapter.notifyDataSetChanged();
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
});

Change your Constructor from DataSnapshot to Map and get the values and set into your local Buyers variable.

public class Buyers {
    private String car_Value;
    private String interest;
    private String driverLicenseNr;
    private String name;
    private String personNr;
    private String phone_Number;


    public Buyers(Map<String,String map){
       car_Value = map.get("Bil");
       interest = map.get("Interresse")
       driverLicenseNr = map.get("Korekortnr")
       name = map.get("Navn")
       personNr = map.get("Personnr")     
       phone_Number =map.get("Telefonnr")
    }
}

Answer 2

you have to do like below.

    mDatabaseReference.addValueEventListener(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        //Buyers buyerList = new Buyers(childSnapshot);

                        for (DataSnapshot childSnapshot: dataSnapshot.getChildren())
                        {
                            Buyers buyerList = childSnapshot.getValue(Buyers.class);
                            //buyerList = childSnapshot.child("PersonNumberTextField").getValue(Buyers.class);
                            //Buyers buyerList = childSnapshot.child("PersonNumberTextField").getValue(Buyers.class);
                            //Buyers buyerList = childSnapshot.getValue(Buyers.class);
                            mUsernames.add(buyerList);
                        }
                        arrayAdapter.notifyDataSetChanged();
                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {

                    }
                });