片段中的接口监听器

Question

抱歉我的问题，我想这很简单。
我有一个需要实现接口侦听器的片段。

package com.tumta.henrique.teste;


import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import com.tumta.henrique.teste.ConsultaEntidades.*;
import java.util.List;


/**
 * A simple {@link Fragment} subclass.
 */
public class EntidadeFragment extends Fragment implements ConsultaConcluidaListener {

    private static final String ARG_SECTION_NUMBER = "section_number";

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


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_entidade, container, false);
        new ConsultaEntidades((ConsultaEntidades)getActivity()).execute();
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
    }

    public static EntidadeFragment newInstance(int sectionNumber){
        EntidadeFragment frag = new EntidadeFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        frag.setArguments(args);
        return frag;
    }

    @Override
    public void onConsultaConcluida(List<String> result) {
        ListView listaEntidades = (ListView) getView().findViewById(R.id.listaentidades);
        ArrayAdapter arrayAdapter = new ArrayAdapter<>(getView().getContext(),android.R.layout.simple_list_item_1, result);
        listaEntidades.setAdapter(arrayAdapter);
    }
}

当它是一个Activity时我需要使用这个：new ConsultaEntidades(this).execute();但是现在我需要在Frag中使用同一行，但是我不能使用this并且当我使用new ConsultaEntidades((ConsultaEntidades)getActivity()).execute();时它显示~无法将 FragmentActivity 转换为 ConsultaEntidades<br><br>ConsultaEntidades` 是我的班级：

package com.tumta.henrique.teste;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

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

import android.content.Context;
import android.os.AsyncTask;
import android.support.v4.app.FragmentActivity;

public class ConsultaEntidades extends AsyncTask<Void, Void, List<String>> {

    private ConsultaConcluidaListener listener;

    private static final String URL_STRING = "http://192.168.0.14:7001/com.henrique.rest/api/v1/status/entidade/";

    public ConsultaEntidades(ConsultaConcluidaListener listener){
        this.listener = listener;
    }

    @Override
    protected List<String> doInBackground(Void... arg0) {
        try {
            String resultado = ConsultaServidor();
            return InterpretaResultado(resultado);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

    private List<String> InterpretaResultado(String resultado) throws JSONException {
        JSONObject object = new JSONObject(resultado);
        JSONArray jsonArray = object.getJSONArray("entidade");
        List<String> listaNomes = new ArrayList<String>();
        for (int i = 0; i < jsonArray.length(); i++) {
            JSONObject jsonWaether = jsonArray.getJSONObject(i);
            //int id = jsonWaether.getInt("ent_id");
            String nome = jsonWaether.getString("ent_nome");
            listaNomes.add(i, nome);
        }

        return listaNomes;
    }

    private String ConsultaServidor() throws IOException {
        InputStream is = null;

        try {
            URL url = new URL(URL_STRING);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(10000);
            conn.setReadTimeout(15000);
            conn.setRequestMethod("GET");
            conn.setDoInput(true);
            conn.connect();
            conn.getResponseCode();

            is = conn.getInputStream();

            Reader reader = null;
            reader = new InputStreamReader(is);
            char[] buffer = new char[2048];
            reader.read(buffer);
            return new String(buffer);
        } finally {
            if (is != null) {
                is.close();
            }
        }
    }

    @Override
    protected void onPostExecute(List<String> result) {
        listener.onConsultaConcluida(result);
        super.onPostExecute(result);

    }

    public interface ConsultaConcluidaListener {
        void onConsultaConcluida(List<String> result);
    }
}

所以您注意到我需要在 frag.xml 中实现该接口。我该怎么做？

Answer 1

你的onCreateView有两个错误

1. 您正在尝试在返回后实例化 AsyncTask
2. 您将getActivity() 投射到接口，而没有Activity 实现它。

它应该看起来像：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
   new ConsultaEntidades(this).execute();
   return inflater.inflate(R.layout.fragment_entidade, container, false);
}