[英]How can I create a ranked leaderboard in Firebase?
我的應用程序中有一個積分系統。 我想在零件中創建一個有序的點列表。 它將按從最高分到最低分的順序排列。 在我寫的代碼中,這個系統不能正常工作。 沒有從最高分到最低分排名。 新評價的用戶出現在頂部。 我該如何解決這個問題? 我希望它從最高分到最低分排序。
記分牌 class:
DatabaseReference UsersRef, RatingsRef;
int currentpage = 1 ;
static final int total_ITEMS = 10 ;
RecyclerView scorrecy ;
UsersRef = FirebaseDatabase.getInstance().getReference().child("Users");
RatingsRef = FirebaseDatabase.getInstance().getReference().child("Ratings");
RatingsRef.keepSynced(false);
getScor();
public void getScor(){
FirebaseRecyclerOptions<ScorModel> options =
new FirebaseRecyclerOptions.Builder<ScorModel>()
.setQuery(RatingsRef.orderByChild("puan").limitToLast(currentpage * total_ITEMS),ScorModel.class)
.build();
FirebaseRecyclerAdapter<ScorModel,ScorViewHolder> adapter
=new FirebaseRecyclerAdapter<ScorModel, ScorViewHolder>(options)
{
@Override
protected void onBindViewHolder(@NonNull final ScorBoard.ScorViewHolder holder, int position, @NonNull ScorModel model) {
final String visit_user_id = getRef(position).getKey();
UsersRef.child(visit_user_id).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.hasChild("isim")){
final String myUsername = dataSnapshot.child("isim").getValue().toString();
holder.userName.setText(myUsername);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
RatingsRef.child(visit_user_id).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.hasChild("puan")){
final String myPoint = dataSnapshot.child("puan").getValue().toString();
holder.userPoint.setText(myPoint+" "+"Puan");
}else {
holder.userPoint.setText("0 Puan");
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
@NonNull
@Override
public ScorBoard.ScorViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.scorboard_model_layout,viewGroup,false);
ScorBoard.ScorViewHolder viewHolder = new ScorBoard.ScorViewHolder(view);
return viewHolder;
}
};
adapter.startListening();
scorrecy.setAdapter(adapter);
}
public static class ScorViewHolder extends RecyclerView.ViewHolder{
TextView userName , userPoint;
View mView;
public ScorViewHolder(@NonNull View itemView) {
super(itemView);
mView= itemView;
userName =itemView.findViewById(R.id.rank_username);
userPoint =itemView.findViewById(R.id.point);
}
}
評分模型;
public String scor, username , currentUserID ;
public ScorModel(){
}
public ScorModel(String scor,String username , String currentUserID) {
this.scor= scor;
this.username = username;
this.currentUserID = currentUserID;
}
public String getScor() {
return scor;
}
public void setScor(String scor) {
this.scor = scor;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
我的數據庫評級;
更新:
RatingsRef = FirebaseDatabase.getInstance().getReference().child("Ratings");
RatingsRef.child(currentUserID).child("Ratings").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
double sum = 0.0;
try {
for (DataSnapshot ds: dataSnapshot.getChildren()) {
Map<String,Object> map = (Map<String, Object>) ds.getValue();
Object rating = map.get("rating");
Double pvalue = Double.parseDouble(String.valueOf(rating));
sum += pvalue;
Map userpoint = new HashMap();
userpoint .put("puan", String.valueOf(sum));
RatingsRef.child(currentUserID).updateChildren(userpoint );
}
}catch (Exception e){
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
您無法獲得所需的結果,因為您的puan
字段包含字符串類型的值而不是數字。 要記住的一件事是,當您對字符串排序時,結果是按字典順序排序的。 例如,10 放在 2 之前。請參見下面的示例:
1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 20, 21, 3
因此,您最好的選擇是將字段的類型更改為數字而不是字符串。
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