Firebase - Retrieve User Information from Database

问题

> I have 3 classes.

• DriverDatabase.class
• AddInfoDriver.class
• DriverProfile.class

In DriverDatabase.class I have set(fName, lName .... and other fields.). Also, put {get; and set;} for those attribtues.

In AddInfoDriver.class I have referenced FirebaseDatabase and DriverDatabase.class so that, whenever a user fills those edittexts, it saves to Firebase Database.

The Problem is: I cannot retrieve those 5 Edittext values in DriverProfile.class below is the piece of code for retrieving.

public class DriverProfile extends Fragment {

@BindView(R.id.btn_save) Button btnsave;
@BindView(R.id.edtx_DoB) EditText edtxdob;
@BindView(R.id.edtx_fname) EditText edtx_fname;
@BindView(R.id.edtx_lname) EditText edtx_lname;
@BindView(R.id.spinner_type) Spinner spn_type;
@BindView(R.id.edtx_number) EditText edtx_number;

private DatabaseReference driverfname, driverlname;


public DriverProfile() {
//Constructed is required

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_my_profile, container, false);
    ButterKnife.bind(this, view);

    driverfname = FirebaseDatabase.getInstance().getReference().child("Drivers").child("fname");
    driverlname  = FirebaseDatabase.getInstance().getReference().child("Drivers").child("lname");

    driverfname.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            edtx_fname.setText(dataSnapshot.getValue(String.class));
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

Didnt write all edittext codes, just see my ValueEventListener for fname of Driver. it is not displaying data when saved by driver in a child("Drivers")

回答1:

To get the values from all drivers please use the following code:

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference driversRef = rootRef.child("Drivers");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String cardNumber = ds.child("cardNumber").getValue(String.class);
            String cardType = ds.child("cardType").getValue(String.class);
            String dateOfBirth = ds.child("dateOfBirth").getValue(String.class);
            String name = ds.child("name").getValue(String.class);
            String surname = ds.child("surname").getValue(String.class);
            Log.d("TAG", cardNumber + " / " + cardType + " / " + dateOfBirth + " / " + name + " / " + surname);
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
driversRef.addListenerForSingleValueEvent(eventListener);

来源：https://stackoverflow.com/questions/46484046/firebase-retrieve-user-information-from-database