How to control the number of items you see in a RecyclerView

Question

How to control the number of items you see in a RecyclerView

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#1 by (1 votes)

-2

As the question says, I have my RecyclerView filled with 50 elements approximately which by default are shown but what I'm looking for is to be able to give a specific number of elements that I want to see, I know that the getItemCount() controls said number of items what is not is how to make it dynamic with a simple EditText

My adapter is this

public class Adaptador extends RecyclerView.Adapter<Adaptador.CartaViewHolder> {
private Context contexto;
private List<Contenido> listacartas;

public Adaptador(Context contexto, List<Contenido> listacartas) {
    this.contexto = contexto;
    this.listacartas = listacartas;
}

@Override
public CartaViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    LayoutInflater inflado = LayoutInflater.from(contexto);
    View vistosa = inflado.inflate(R.layout.cartas, null);
    return new CartaViewHolder(vistosa);
}

@Override
public void onBindViewHolder(CartaViewHolder holder, int position) {

    Contenido datos = listacartas.get(position);

    holder.nombre.setText(datos.getNombre());
    holder.imagen.setImageDrawable(contexto.getResources().getDrawable(datos.getImagen()));
}

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

class CartaViewHolder extends RecyclerView.ViewHolder {

    ImageView imagen;
    TextView nombre;

    public CartaViewHolder(View itemView) {
        super(itemView);

        imagen = itemView.findViewById(R.id.imageView);
        nombre = itemView.findViewById(R.id.textView);
    }
}

My mainActivity where I have the edittext to give the exact number of items to recycle

public class MainActivity extends AppCompatActivity {
Button click;
BlankFragment blankFragment;
EditText numero;
RecyclerView reciclador;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    click = findViewById(R.id.fragmento);
    numero = findViewById(R.id.numero);

    blankFragment = new BlankFragment();
    findViewById(R.id.fragmento).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            getSupportFragmentManager().beginTransaction().add(R.id.contenedor, blankFragment).addToBackStack(null).commit();
            click.setVisibility(View.INVISIBLE);
            numero.setVisibility(View.INVISIBLE);
        }
    });


}

@Override
public void onBackPressed() {
    super.onBackPressed();
    click.setVisibility(View.VISIBLE);
    numero.setVisibility(View.VISIBLE);
}

And the fragment where I fill the list that is shown in the recicleView which I need to retrace the number of items that is displayed

public class BlankFragment extends Fragment {
RecyclerView reciclador;
List<Contenido> listota;
LinearLayoutManager layoutManager
        = new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false);

public BlankFragment() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_blank, container, false);
    listota = new ArrayList<>();

    reciclador = view.findViewById(R.id.Lista);
    reciclador.setLayoutManager(layoutManager);
    reciclador.setHasFixedSize(true);
    reciclador.setLayoutManager(new LinearLayoutManager(getContext()));
    listota.add(new Contenido(R.drawable.alacran, "Alacran"));
    listota.add(new Contenido(R.drawable.apache, "Apache"));
    listota.add(new Contenido(R.drawable.arana, "Araña"));
    listota.add(new Contenido(R.drawable.arbol, "Arbol"));
    listota.add(new Contenido(R.drawable.arpa, "Arpa"));
    listota.add(new Contenido(R.drawable.bandera, "Bandera"));
    listota.add(new Contenido(R.drawable.barril, "Barril"));
    listota.add(new Contenido(R.drawable.borracho, "Borracho"));
    listota.add(new Contenido(R.drawable.bota, "Bota"));
    listota.add(new Contenido(R.drawable.botella, "Botella"));
    listota.add(new Contenido(R.drawable.calavera, "Calavera"));
    listota.add(new Contenido(R.drawable.camaron, "Camaron"));
    listota.add(new Contenido(R.drawable.campana, "Campana"));
    listota.add(new Contenido(R.drawable.cantaro, "Catrin"));
    listota.add(new Contenido(R.drawable.cazo, "Cazo"));
    listota.add(new Contenido(R.drawable.chalupa, "Chalupa"));
    listota.add(new Contenido(R.drawable.corazon, "Corazon"));
    listota.add(new Contenido(R.drawable.corona, "Corona"));
    listota.add(new Contenido(R.drawable.cotorro, "Cotorro"));
    listota.add(new Contenido(R.drawable.dama, "Dama"));
    listota.add(new Contenido(R.drawable.diablito, "Diablito"));
    listota.add(new Contenido(R.drawable.escalera, "Escalera"));
    listota.add(new Contenido(R.drawable.estrella, "Estrella"));
    listota.add(new Contenido(R.drawable.gallo, "Gallo"));
    listota.add(new Contenido(R.drawable.garza, "Garza"));
    listota.add(new Contenido(R.drawable.gorrito, "Gorrito"));
    listota.add(new Contenido(R.drawable.jaras, "Jarras"));
    listota.add(new Contenido(R.drawable.luna, "Luna"));
    listota.add(new Contenido(R.drawable.maceta, "Maceta"));
    listota.add(new Contenido(R.drawable.mano, "Mano"));
    listota.add(new Contenido(R.drawable.melon, "Melon"));
    listota.add(new Contenido(R.drawable.muerte, "Muerte"));
    listota.add(new Contenido(R.drawable.mundo, "Mundo"));
    listota.add(new Contenido(R.drawable.musico, "Musico"));
    listota.add(new Contenido(R.drawable.negro, "Negro"));
    listota.add(new Contenido(R.drawable.nopal, "Nopal"));
    listota.add(new Contenido(R.drawable.pajaro, "Pajaro"));
    listota.add(new Contenido(R.drawable.palma, "Palma"));
    listota.add(new Contenido(R.drawable.paragauas, "Paraguas"));
    listota.add(new Contenido(R.drawable.pera, "Pera"));
    listota.add(new Contenido(R.drawable.pescado, "Pescado"));
    listota.add(new Contenido(R.drawable.pino, "Pino"));
    listota.add(new Contenido(R.drawable.rana, "Rana"));
    listota.add(new Contenido(R.drawable.rosa, "Rosa"));
    listota.add(new Contenido(R.drawable.sandolon, "Sandolon"));
    listota.add(new Contenido(R.drawable.sandria, "Sandia"));
    listota.add(new Contenido(R.drawable.sirena, "Sirena"));
    listota.add(new Contenido(R.drawable.sol, "Sol"));
    listota.add(new Contenido(R.drawable.soldado, "Soldado"));
    listota.add(new Contenido(R.drawable.tambor, "Tambor"));
    listota.add(new Contenido(R.drawable.valiente, "Valiente"));
    listota.add(new Contenido(R.drawable.venado, "Venado"));
    listota.add(new Contenido(R.drawable.violoncelo, "Violonchelo"));



    Adaptador adapter = new Adaptador(getContext(), listota);

    reciclador.setAdapter(adapter);

    return view;
}

java android-studio recyclerview

asked by Diego Pineda Cervantes 23.04.2018 в 19:06

source

1 answer

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score 1 · Accepted Answer

What you need is to use the notifyDataSetChanged() method. Then in your editText you get with the textWatcher text and there send to update your adapter.

editText.addTextChangedListener(new TextWatcher() {
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        try{
            int numItems = Integer.parseInt(s);
            adapter.setNumItems(numItems);
            adapter.notifyDataSetChanged();
        } catch(Exception e){
             //no es numero
        }
    }

and in your adapter you add a method setNumItems (or whatever you want to call it) and you set the number of items that the editText says and you change the value of items displayed in getItemCount

public class Adaptador......
    private int numItems;

    public Adaptador(Context contexto, List<Contenido> listacartas) {
        this.contexto = contexto;
        this.listacartas = listacartas;
        this.numItems = listacartas.size(); //por default muestra todos, aca le cambias a un valor fijo o como lo necesites
    }

    @Override
    public int getItemCount() {
        //igual y valida aca que numItems sea <= listacartas.size() para que no provoque error
        return numItems;
    }

    void setNumItems(int numItems){
        this.numItems = numItems;
    }