[英]How can I group same values into 1 single recyclerview item?
我有一個 recyclerview,其中我使用 JAVA 列出了 Firebase 的費用類別,我希望對類別進行分組,所以我只得到 1 個名為 FOOD、ENTERTAINMENT 等的 recyclerview 項目,以及該類別中每個項目的總金額。
這是我的 recyclerview 結果了;
這是我的適配器 class;
public class CategoriesAdapter extends RecyclerView.Adapter<CategoriesAdapter.ViewHolder> {
private Context mContext;
private ArrayList<Expense> categories;
public CategoriesAdapter(Context mContext, ArrayList<Expense> categories) {
this.mContext = mContext;
this.categories = categories;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.categories_retrieve_layout, parent, false);
return new ViewHolder(view);
}
@SuppressLint("SetTextI18n")
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
final Expense expense = categories.get(position);
holder.category.setText("" + expense.getCategory());
holder.amount.setText("$ " + formatNumberCurrency(String.valueOf(expense.getAmount())));
}
@Override
public int getItemCount() {
return categories.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
private TextView category;
private TextView amount;
private TextView percentage;
public ViewHolder(@NonNull View itemView) {
super(itemView);
category = itemView.findViewById(R.id.category_name);
amount = itemView.findViewById(R.id.category_total_amount);
percentage = itemView.findViewById(R.id.percentage_indicator);
}
}
private static String formatNumberCurrency(String amount) {
DecimalFormat formatter = new DecimalFormat("###,###,###");
return formatter.format(Double.parseDouble(amount));
}
}
這是我讀取數據的方式
final Calendar c = Calendar.getInstance();
@SuppressLint("SimpleDateFormat") DateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy");
String date = dateFormat.format(c.getTime());
DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference().child("Expenses").child(Objects.requireNonNull(mAuth.getCurrentUser()).getUid());
Query query = databaseReference.orderByChild("date").equalTo(date);
query.addValueEventListener(new ValueEventListener() {
@SuppressLint("NotifyDataSetChanged")
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
expenses.clear();
for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
Expense expense = dataSnapshot.getValue(Expense.class);
expenses.add(expense);
}
categoriesAdapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
});
在這里,我希望得到的 output
關於如何為此創建邏輯的任何建議?
這是我在嘗試使用 Sambhav 時遇到的錯誤。 K 的回答:
您可以在將值添加到列表時檢查它是否已經存在。 嘗試這個:
query.addValueEventListener(new ValueEventListener() {
@SuppressLint("NotifyDataSetChanged")
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
expenses.clear();
for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
Expense expense = dataSnapshot.getValue(Expense.class);
boolean exists = false;
int count = 0;
for(int i = 0; i < expenses.size(); i++){
count = i;
exists = expenses.get(i).getCategory().equalsIgnoreCase(expense.getCategory());
if(exists) break;
}
if(exists){
expenses.get(count).setAmount(expenses.get(i).getAmount()() + expense.getAmount());
}else{
expenses.add(expense);
}
}
categoriesAdapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
error.printStackTrace();
}
});
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