How to use HashMap data in RecyclerView?

Question

I count the same value with HashMap (says hasmap ), but how to display key and value of the HashMap in RecyclerView ?

HashMap<String, Integer> hasmap = new HashMap<>();
for (int i = 0; i < data.length(); i++){
    JSONObject List_data_kecamatan = data.getJSONObject(i);

    String nama_kecamatan = List_data_kecamatan.getString("dapil_kecamatan");

    int count = 0;
    if (hasmap.containsKey(nama_kecamatan)){
        count = hasmap.get(nama_kecamatan)+1;
        hasmap.put(nama_kecamatan, count);
    }else {
        hasmap.put(nama_kecamatan, 1);
    }

}

I Using JSON Object as key in hasmap .

Answer 1

Thinking something like:

public class MyRVAdapter extends RecyclerView.Adapter<MyViewHolder> {

    private HashMap<String, String> mData;
    private ArrayList<Pair<String, String>> mActualData;

    public MyRVAdapter(HashMap<String, String> mData) {
        this.mData = mData;
        mActualData = new ArrayList<>(mData.size());
        mData.forEach((s, s2) -> mActualData.add(new Pair<>(s, s2)));
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        TextView v = (TextView) LayoutInflater.from(parent.getContext())
                .inflate(R.layout.my_text_view, holder, false);

        return new MyViewHolder(v);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        holder.mTextView.setText(
                String.format("%s - %s", mActualData.get(position).first, mActualData.get(position).second)
        );
    }

    @Override
    public int getItemCount() {
        return mActualData.size();
    }
}

public class MyViewHolder extends RecyclerView.ViewHolder {

    TextView mTextView;
    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        mTextView = (TextView)itemView;
    }
}

So this will convert the HashMap into an ArrayList of Key Value Pairs (the .forEach will only work on API 24+; swap out with an Iterator if you need lower version support).

You would then use the setAdapter method for the RecyclerView in your layout.