Constructor <Classadapter> in <Classadapter> cannot be applied to certain types

Question

I’m trying to implement a Searchview next to Recyclerview to make filtering book records occur. I am having problems in the following file line ListDonos.java:

Row:

recyclerAdapter = new DonoAdapter();

The error of this line is:

error: constructor Donoadapter in class Donoadapter cannot be Applied to Given types; required: List<Dono>,Context found: no Arguments Reason: actual and formal argument lists differ in length.

• Filing cabinet ListarDonos.java

public class ListarDonos extends AppCompatActivity {

    RecyclerView recyclerView;
    DonoAdapter recyclerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_listar_donos);
        setTitle("Listar donos");

        recyclerView = findViewById(R.id.recyclerView);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setHasFixedSize(true);

        Conexao conexao = new Conexao(this);
        List<Dono> donos = conexao.ReadDonos();
        
        if (donos.size() > 0){
            DonoAdapter donoadapter = new DonoAdapter(donos,ListarDonos.this);
            recyclerView.setAdapter(donoadapter);
        } else {
            Toast.makeText(this, "Não existem donos no banco de dados.", Toast.LENGTH_SHORT).show();
        }
    }
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu){
        getMenuInflater().inflate(R.menu.pesquisar_dono,menu);
        MenuItem menuItem = menu.findItem(R.id.buscar_dono);
        SearchView searchView = (SearchView) menuItem.getActionView();
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }
            @Override
            public boolean onQueryTextChange(String newText) {
                recyclerAdapter.getFilter().filter(newText);
                return false;
            }
        });
        return super.onCreateOptionsMenu(menu);
    }
}

• Filing cabinet DonoAdapter.java

public class DonoAdapter extends RecyclerView.Adapter<DonoAdapter.ViewHolder> implements Filterable {

    List<Dono> donos;
    List<Dono> donos2;
    Context context;
    Conexao conexao;

    public DonoAdapter(List<Dono> donos, Context context) {
        this.donos = donos;
        this.donos2 = new ArrayList<>(donos);
        this.context = context;
        conexao = new Conexao(context);
    }
    // Método para obter o filtro
    @Override
    public Filter getFilter() {
        return filter;
    }
    // Realiza a filtragem
    Filter filter = new Filter() {
        @Override
        protected FilterResults performFiltering(CharSequence charSequence) {
            List<Dono> filtro_donos = new ArrayList<>();
            if (charSequence.toString().isEmpty()){
                filtro_donos.addAll(donos2);
            } else {
                for (Dono doninho: donos2){
                    if (doninho.getNome_dono().toLowerCase().contains(charSequence.toString().toLowerCase())){
                        filtro_donos.add(doninho);
                    }
                }
            }
            FilterResults filterResults = new FilterResults();
            filterResults.values = filtro_donos;
            return filterResults;
        }
        @Override
        protected void publishResults(CharSequence constraint, FilterResults filterResults) {
            donos.clear();
            donos.addAll((Collection<? extends Dono>) filterResults.values);
            notifyDataSetChanged();
        }
    };
}

Answer 1

Your class DonoAdapter stretches RecyclerView.Adapter but in the line that gives error:

recyclerView.getFilter().filter(newText); // ERROR: Cannot resolv method 'getFilter()

is called the getFilter of RecyclerView which, by the text of the error message, does not have the method getFilter().

Consulting to documentation of Recyclerview you can see that the class RecyclerView.Adapter does not have the filter method. You will need to cast to call DonoAdapter.filter() which is a method unique to your Adapter. Something like:

 DonoAdapter donoAdapter = (DonoAdapter)recyclerView.getAdapter();
 donoAdapter.filter(newText);