On the Adapter class How to get key and value from HashMap

Question

On my RecyclerViewAdapter class i'm passing HashMap<String,ArrayList<Custom>> as data, now i want to get key & value for every position but i don't know how i should do this! thanks in advance

public class Main_Recycler_Single_Row extends RecyclerView.Adapter<Main_Recycler_Single_Row.ViewHolder> {



private Context mContext;
private HashMap<String,ArrayList<Products>> dataSet;

public Main_Recycler_Single_Row(Context mContext, HashMap<String,ArrayList<Products>> mDataSet) {
    this.mContext = mContext;
    this.dataSet = mDataSet;

} @Override
public void onBindViewHolder(@NonNull final ViewHolder holder, int position) {

    Map.Entry<String,ArrayList<Products>> entry=(Map.Entry<String,ArrayList<Products>>) dataSet.entrySet();//this line is my problem!


    holder.header.setText(entry.getKey());

    holder.mRecyclerView.setLayoutManager(new LinearLayoutManager(mContext,LinearLayoutManager.HORIZONTAL,false));
    holder.mRecyclerView.setHasFixedSize(true);
    holder.mRecyclerView.setAdapter(new Main_Recycler_Sinle_Item(mContext,entry.getValue()));

}

Answer 1

If you are trying to get Value from HashMap using position, you also need to maintain Array of keys

keys = (String[])mDataSet.keySet().toArray();

Your ViewHolder class will look like:

public Main_Recycler_Single_Row(Context mContext, HashMap<String,ArrayList<Products>> mDataSet) {
    this.mContext = mContext;
    this.dataSet = mDataSet;
    keys = (String[])mDataSet.keySet().toArray();

} @Override
public void onBindViewHolder(@NonNull final RecyclerView.ViewHolder holder, int position) {

    holder.header.setText(keys[position]);

    holder.mRecyclerView.setLayoutManager(new LinearLayoutManager(mContext,LinearLayoutManager.HORIZONTAL,false));
    holder.mRecyclerView.setHasFixedSize(true);
    holder.mRecyclerView.setAdapter(new Main_Recycler_Sinle_Item(mContext,dataSet.get(keys[position])));

}