Cannot call method of RecyclerView adapter from an activity

Question

I am trying to set the data for recycler view to display from an AsyncTask. I am calling the method setdataEntries from the postExecute of inner class AsyncTask. But the android studio is showing me error could not find the method.

Adapter class

public class EntryAdapter extends RecyclerView.Adapter<EntryAdapter.ViewHolder> {
List<UserTuple> entries;
final private itemClickListener mOnClickListener;
public interface itemClickListener{
    void onItemClick(UserTuple utuple);
}

public EntryAdapter(itemClickListener clickhandler) {
    mOnClickListener = clickhandler;
}
public void setdataEntries(List<UserTuple> Data) {
    entries = Data;
    notifyDataSetChanged();
}
@Override
public EntryAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.singleusertuple,parent,false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(EntryAdapter.ViewHolder holder, int position) {

    holder.Username.setText(entries.get(position).getUsername());
    holder.Password.setText(entries.get(position).getPassword());

}

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

public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    private TextView Username;
    private TextView Password;
    private CardView card;
    public ViewHolder(View itemView) {
        super(itemView);
        Username = itemView.findViewById(R.id.susername);
        Password=itemView.findViewById(R.id.pass);
        itemView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        int adapterPosition = getAdapterPosition();
        UserTuple ut=new UserTuple(entries.get(adapterPosition).getUsername(),entries.get(adapterPosition).getPassword());
        mOnClickListener.onItemClick(ut);
    }
}
}

Calling Activity

public class Usertuple extends AppCompatActivity implements EntryAdapter.itemClickListener {
private RecyclerView recyclerView ;
private RecyclerView.Adapter adapater;
private SnapHelper snapHelper;
private List<UserTuple> entries;
private ProgressBar mLoadingIndicator;
private Bundle extras;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_logins);
    extras = getIntent().getExtras();
    //String site= extras.getString("sitename");
    mLoadingIndicator = (ProgressBar) findViewById(R.id.pb_loading_indicator);

    Log.i("Logins","Size of returned list "+entries.size());
    recyclerView = findViewById(R.id.recycleview);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setHasFixedSize(true);
    adapater = new EntryAdapter(this);
    recyclerView.setAdapter(adapater);
    snapHelper= new LinearSnapHelper();
    snapHelper.attachToRecyclerView(recyclerView);
    dataView();

}
public void dataView() {
    String site= extras.getString("sitename");
    recyclerView.setVisibility(View.VISIBLE);
    new FetchDataTask().execute(site);
}

@Override
public void onItemClick(UserTuple utuple) {

}
private String key(){
    SharedPreferences sharedPref = getSharedPreferences(
            "User", this.MODE_PRIVATE);
    final String passphrase = sharedPref.getString("userid", "none");
    return passphrase;
}
public void showerror(){
    recyclerView.setVisibility(View.GONE);
    Toast.makeText(this,"Error in retrieving",Toast.LENGTH_SHORT).show();

}
public setdata(List<UserTuple> data){
    adapater.setdataEntries(data);
}
public class FetchDataTask extends AsyncTask<String, Void, List<UserTuple>> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        mLoadingIndicator.setVisibility(View.VISIBLE);
    }

    @Override
    protected List<UserTuple> doInBackground(String... params) {

        /* If there's no zip code, there's nothing to look up. */
        if (params.length == 0) {
            return null;
        }

        String site = params[0];

        try {
            AppDatabase db = Room.databaseBuilder(getApplicationContext(),AppDatabase.class, "production")
                    .build();
            entries =db.entryDao().getSpecific(site);
            for(UserTuple ut : entries){
                Log.i("password",ut.getPassword());
                String st = new Decryption().decrypt(ut.getPassword(),key());
                Log.i("After decryption",st);
                ut.setPassword(st);
            }
            return entries;

        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    @Override
    protected void onPostExecute(List<UserTuple> Data) {
        mLoadingIndicator.setVisibility(View.INVISIBLE);
        if (Data != null) {
            adapater.setdataEntries(Data);
        } else {
            showerror();
        }
    }
}


}

I want the database calls to be a background task. I don't want the activity to freeze waiting for database calls. Any ideas? Thanks

Answer 1

Declare adapter like

private EntryAdapter adapter;

instead of

private RecyclerView.Adapter adapater;

because RecyclerView.Adapter class does not have any method named setdataEntries but only EntryAdapter class has this method so only the object of type EntryAdapter can call setdataEntries method.

Or you can use down-casting as

((EntryAdapter)adapater).setdataEntries(data);