如何将 Firebase 数据库中的正确数据放入我的 RecyclerView？

Question

I'm creating an app in Android Studio, which connects to Firebase realtime database. In the database I have the following structure:

First thing : I would have preferred a structure like:

users -> email -> {23, 13, 4, .., 5} but i found out that with Firebase I must have a pair key - value so I can't get this kind of structure. Am I right?!

Anyways.. I created a class like this:

public class ItemModel {

    private int itemImg;
    private int deleteFav;
    private String itemLine;

    public ItemModel(){}

    public ItemModel(String itemLine) {
        this.itemLine = itemLine;
    }

    public ItemModel(int itemImg,  String itemLine, int deleteFav) {
        this.itemImg = itemImg;
        this.deleteFav = deleteFav;
        this.itemLine = itemLine;
    }

    public int getItemImg() {
        return itemImg;
    }

    public int getDeleteFav() {
        return deleteFav;
    }

    public String getItemLine() {
        return itemLine;
    }

    @Override
    public String toString() {
        return itemLine;
    }
}

And this is my Firebase Database Helper class:

public class FirebaseDatabaseHelper {

    private FirebaseDatabase firebaseDatabase;
    private DatabaseReference databaseReferenceFavorites;
    private List<ItemModel> favouriteList = new ArrayList<>();
    private FirebaseAuth mAuth;

    // In order to link our process we need to create interface
    public interface  DataStatus {
        void DataIsLoaded(List<ItemModel> favourites, List<String> keys);
    }

    public FirebaseDatabaseHelper(){
        mAuth = FirebaseAuth.getInstance();
        firebaseDatabase = FirebaseDatabase.getInstance();
        databaseReferenceFavorites =  firebaseDatabase.getReference("users");
    }

    public void readFavoriteLines(final DataStatus dataStatus){
        databaseReferenceFavorites.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {  // asincrono
                favouriteList.clear();
                List<String> keys = new ArrayList<>();
                for (DataSnapshot keyNode : dataSnapshot.getChildren()){
                    keys.add(keyNode.getKey());
                    ItemModel favourite = keyNode.getValue(ItemModel.class);
                    favouriteList.add(favourite);
                }

                dataStatus.DataIsLoaded(favouriteList, keys);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });
    }

    static String encodeUserEmail(String userEmail) {
        return userEmail.replace(".", ",");
    }
}

When I run, from this class i get the error " No setter/field for test@email,com found on class com.example.xyItemModel ". I read other people having this error here but can't understand which part of my code is not ok. I tried to add setters and to change names of "v1" in database to "itemLine" but still having the same error.

The thing is that actually my item appear in the UI when I run but it miss one data, the itemLine. The row must be img1 - itemLine - img2 but it shows only img1 - nothing - img2. I need to take only the value of each test@email,com (itemLine) and put this value (23 for example) in my RecyclerView item. The row should look like this:

Answer 1

This will show nothing because you're trying to get value from users not test@email,com

Try this

Instead of this

databaseReferenceFavorites =  firebaseDatabase.getReference("users");
    

this should fetch your data Create database reference to the location

public FirebaseDatabaseHelper(){
        mAuth = FirebaseAuth.getInstance();
        firebaseDatabase = FirebaseDatabase.getInstance();
       DatabaseReference databaseReferenceFavorites =  
       firebaseDatabase.getReference("users");
       DatabaseReference databaseReferenceitemline = 
       databaseReferenceFavorites.child("test@gmail,com")
}
public void readFavoriteLines(final DataStatus dataStatus){
        databaseReferenceitemline.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {  // asincrono
                favouriteList.clear();
                List<String> keys = new ArrayList<>();
                for (DataSnapshot keyNode : dataSnapshot.getChildren()){
                    keys.add(keyNode.getKey());
                    ItemModel favourite = keyNode.getValue(ItemModel.class);
                    favouriteList.add(favourite);
                }

                dataStatus.DataIsLoaded(favouriteList, keys);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });
    }

    static String encodeUserEmail(String userEmail) {
        return userEmail.replace(".", ",");
    }
}

In this snippet

• databaseReferenceFavorites points to user
• databaseReferenceitemline points to test@gmail,com