Question

我有一个从RecyclerView.Adapter扩展的类，在该类中我有两个按钮，一个用于更新，一个用于删除，问题是我想使用这些按钮来调用另一个类中的方法它扩展了Fragments但我不知道如何将实例设置为我的方法，我也想传递一个参数。

这是我的类，它来自RecyclerView.Adapter：

package com.example.enriq.examen_tareas_segundo_plano_enrique_espinosa.adapter;

import android.app.Activity;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CompoundButton;
import android.widget.TextView;
import android.widget.Toast;


import com.example.enriq.examen_tareas_segundo_plano_enrique_espinosa.R;
import com.example.enriq.examen_tareas_segundo_plano_enrique_espinosa.tareasFragmento;

import java.util.ArrayList;
/**
 * Created Enrique Espinosa.
 */
public class TareasAdapter extends RecyclerView.Adapter<TareasAdapter.UsuarioHolder>{

    private Activity activity;
    private ArrayList<Tareas> tareas;


    public TareasAdapter(Activity activity, ArrayList<Tareas> tareas) {
        this.activity = activity;
        this.tareas = tareas;

    }

        public class UsuarioHolder extends RecyclerView.ViewHolder {

        public TextView txtId;
        public TextView txtNombreUsuario;
        public TextView txtNota;
        public TextView txtEstudiante;
        public int pasId;

        Button btnEliminar = (Button)itemView.findViewById(R.id.btnEliminar);
        Button btnActualizar = (Button)itemView.findViewById(R.id.btnActualizar);

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

            txtId = (TextView) itemView.findViewById(R.id.txt_id);
            txtNombreUsuario = (TextView) itemView.findViewById(R.id.txt_nombre_usuario);
            txtNota = (TextView) itemView.findViewById(R.id.txt_nota);
            txtEstudiante = (TextView) itemView.findViewById(R.id.txtEstudiante);

        }
    }

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

        View view = activity.getLayoutInflater().inflate(R.layout.plantilla_usuariosegundo, parent, false);
        UsuarioHolder holder = new UsuarioHolder(view);

        return holder;
    }

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

        holder.txtId.setText(tareas.get(position).getId());
        holder.txtNombreUsuario.setText("Tarea: "+ tareas.get(position).getNombreTarea());
        holder.txtNota.setText("Nota: "+ tareas.get(position).getNota());
        holder.txtEstudiante.setText("Estudiante: "+ tareas.get(position).getEstudiante());
    }

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

这是我的课程，从片段延伸：

package com.example.enriq.examen_tareas_segundo_plano_enrique_espinosa;

import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.support.v7.app.AlertDialog;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;
import com.example.enriq.examen_tareas_segundo_plano_enrique_espinosa.adapter.Tareas;
import com.example.enriq.examen_tareas_segundo_plano_enrique_espinosa.adapter.TareasAdapter;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by Enriq on 26/04/2018.
 */

public class tareasFragmento extends Fragment {

    private String url = "http://192.168.1.128:8080/WebServiceExamenFinal/webapi/tareas";
    private ArrayList<Tareas> estudiantes = new ArrayList<>();

    //Si no funciona esto se puede borrar

    AlertDialog alertDialog;
    private List<Tareas> tareasList;
    private TareasAdapter tareasAdapter;
    private int assiId;

    public tareasFragmento() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.activity_tareas, container, false);


        RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.recycler_list);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new GridLayoutManager(getContext(), 2,
                GridLayoutManager.VERTICAL, false));

        final TareasAdapter adapter = new TareasAdapter(getActivity(), estudiantes);
        recyclerView.setAdapter(adapter);

        RequestQueue queue = Volley.newRequestQueue(getContext());
        final ProgressDialog dialog = new ProgressDialog(getContext());
        dialog.setMessage("Por favor espere...");
        dialog.show();
        try {
            JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(Request.Method.GET, url,
                    new Response.Listener<JSONArray>() {
                        @Override
                        public void onResponse(JSONArray response) {
                            deserializarJSONArray(response);
                            adapter.notifyDataSetChanged();
                            if (dialog.isShowing()) dialog.dismiss();
                        }
                    },
                    new Response.ErrorListener() {
                        @Override
                        public void onErrorResponse(VolleyError error) {
                            Toast.makeText(getActivity(),
                                    "Error al realizar la petición\n" + error.getMessage(),
                                    Toast.LENGTH_LONG).show();
                            if (dialog.isShowing()) dialog.dismiss();
                        }
                    });
            queue.add(jsonArrayRequest);
        }catch (Exception e) {
            Toast.makeText(getActivity(),"El error es: "+e,Toast.LENGTH_LONG).show();
        }

        return view;
    }

    public void deserializarJSONArray(JSONArray jsonArray) {

        for (int i = 0; i < jsonArray.length(); i++) {
            try {
                JSONObject item = jsonArray.getJSONObject(i);
                Tareas tareas = new Tareas();
                tareas.setId(item.getString("id"));
                tareas.setNombreTarea(item.getString("nombreUsuario"));
                tareas.setEstudiante(item.getString("estudiante"));
                tareas.setNota(item.getString("nota"));

                estudiantes.add(tareas);
            } catch (JSONException e) {
                Toast.makeText(getActivity(), "Error al procesar la respuesta de la petición: " + e,
                        Toast.LENGTH_SHORT).show();
            }
        }
    }

    public void delete(int id){

        Toast.makeText(getActivity(),"Este es el id recibido: "+id,Toast.LENGTH_LONG).show();
    }

    public int getAssiId(){
        Toast.makeText(getActivity(),"Estas en el get de tareas fragmento",Toast.LENGTH_LONG).show();
        return assiId;
    }

}

我尝试过类似的事情：

tareasFragmento tarea = new tareasFragmento(); 
tarea.eliminar(id);

但它会返回此错误：

尝试调用虚拟方法＆＃39; android.content.res.Resources android.content.Context.getResources（）＆＃39; null对象引用

Answer 1

我已更新您的适配器。

public class TareasAdapter extends RecyclerView.Adapter<TareasAdapter.UsuarioHolder> {

    private Activity activity;
    private ArrayList<Tareas> tareas;
    private OnClickButton callback;

    public TareasAdapter(Activity activity, ArrayList<Tareas> tareas) {
        this.activity = activity;
        this.tareas = tareas;
    }

    public void setCallback(OnClickButton callback) {
        this.callback = callback;
    }

    public class UsuarioHolder extends RecyclerView.ViewHolder {

        public TextView txtId;
        public TextView txtNombreUsuario;
        public TextView txtNota;
        public TextView txtEstudiante;
        public int pasId;

        Button btnEliminar;
        Button btnActualizar;

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

            txtId = (TextView) itemView.findViewById(R.id.txt_id);
            txtNombreUsuario = (TextView) itemView.findViewById(R.id.txt_nombre_usuario);
            txtNota = (TextView) itemView.findViewById(R.id.txt_nota);
            txtEstudiante = (TextView) itemView.findViewById(R.id.txtEstudiante);
            btnEliminar = (Button) itemView.findViewById(R.id.btnEliminar);
            btnActualizar = (Button) itemView.findViewById(R.id.btnActualizar);

        }
    }

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

        View view = activity.getLayoutInflater().inflate(R.layout.plantilla_usuariosegundo, parent, false);
        UsuarioHolder holder = new UsuarioHolder(view);

        holder.btnActualizar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                callback.onClickUpdate();
            }
        });
        holder.btnEliminar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                callback.onClickDelete();
            }
        });

        return holder;
    }

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

        holder.txtId.setText(tareas.get(position).getId());
        holder.txtNombreUsuario.setText("Tarea: " + tareas.get(position).getNombreTarea());
        holder.txtNota.setText("Nota: " + tareas.get(position).getNota());
        holder.txtEstudiante.setText("Estudiante: " + tareas.get(position).getEstudiante());
    }

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

    public interface OnClickButton {
        void onClickUpdate();

        void onClickDelete();
    }
}

修改现在，使用此适配器的片段实现接口OnClickButton。然后，您将能够操纵活动中的点击事件，这是操作/与片段通信的正确位置。

最后在初始化适配器调用之后：

adapter.setCallback(this);

从一个扩展自RecyclerView.Adapter

1 个答案: