I want to Sort from top to bottom on Firebase Database. Can anyone help me? I tried to use collections, but it didn't work.
Activity where starts the recycler view
public class activity_ranking extends AppCompatActivity {
RecyclerView rv;
List<User> users;
Adapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_ranking);
rv = (RecyclerView)findViewById(R.id.recycler);
rv.setLayoutManager(new LinearLayoutManager(this));
users = new ArrayList<>();
FirebaseDatabase database = FirebaseDatabase.getInstance();
adapter = new Adapter(users);
Collections.sort(users, new Comparator<User>(){
public int compare(User obj1, User obj2)
{
// TODO Auto-generated method stub
return (obj1.getStars() > obj2.getStars()) ? +1: (obj1.getStars() > obj2.getStars()) ? 1:0 ;
}
});
rv.setAdapter(adapter);
Query query = database.getReference().child("users").orderByChild("stars");
query.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
users.removeAll(users);
for (DataSnapshot snapshot:
dataSnapshot.getChildren()) {
User user = snapshot.getValue(User.class);
users.add(user);
}
adapter.notifyDataSetChanged();
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
MyClass user
public class User {
public User() {
}
String username;
String name;
int stars;
String id;
public User(String username, String name, int stars, String id) {
this.username = username;
this.name = name;
this.stars = stars;
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getStars() {
return stars;
}
public void setStars(int stars) {
this.stars = stars;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
}
