android - 数据没有加载，也没有错误或警告显示

Question

我遇到了麻烦，我尝试将我的 fragment 转换为 Activity ，当我尝试运行应用程序时，所有数据都未加载并且没有显示警告或错误，请有人帮忙

import android.app.Dialog;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.TextView;

import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.NetworkImageView;

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

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

public class RekomendasiExercise extends AppCompatActivity implements AdapterView.OnItemClickListener{

    // Log tag
    private static final String TAG = AbdominalFragment.class.getSimpleName();

    // Movies json url
    private static final String url = "http://......";
    private ProgressDialog pDialog;
    private List<Exercise> exerciseList = new ArrayList<Exercise>();
    private ListView listView;
    private CustomListAdapter adapter;

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

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        hidePDialog();
    }

    private void hidePDialog() {
        if (pDialog != null) {
            pDialog.dismiss();
            pDialog = null;
        }
    }


    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.activity_list, container, false);
        // Inflate the layout for this fragment

        final ListView listView = (ListView) rootView.findViewById(R.id.list);
        adapter = new CustomListAdapter(this, exerciseList);
        listView.setAdapter(adapter);

        pDialog = new ProgressDialog(this);
        // Showing progress dialog before making http request
        pDialog.setMessage("Loading...");
        pDialog.show();

        if(exerciseList.isEmpty()) {
            // Creating volley request obj
            JsonArrayRequest exerciseReq = new JsonArrayRequest(url,
                    new Response.Listener<JSONArray>() {
                        @Override
                        public void onResponse(JSONArray response) {
                            Log.d(TAG, response.toString());
                            hidePDialog();

                            exerciseList.clear();

                            // Parsing json
                            for (int i = 0; i < response.length(); i++) {
                                try {

                                    JSONObject obj = response.getJSONObject(i);
                                    Exercise exercise = new Exercise();
                                    if (obj.getString("tipe").equals("abdominal")) {
                                        exercise.setNama(obj.getString("nama"));
                                        exercise.setGambar1(obj.getString("gambar1"));
                                        // Genre is json array
                                        // adding movie to movies array
                                        exerciseList.add(exercise);
                                    }
                                } catch (JSONException e) {
                                    e.printStackTrace();
                                }

                            }

                            // notifying list adapter about data changes
                            // so that it renders the list view with updated data
                            adapter.notifyDataSetChanged();
                        }
                    }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.d(TAG, "Error: " + error.getMessage());
                    hidePDialog();

                }
            });

            // Adding request to request queue
            AppController.getInstance().addToRequestQueue(exerciseReq);
        }else{
            hidePDialog();
        }

        listView.setOnItemClickListener(this);
        return rootView;
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View convertView, int position, long id) {
        // Create custom dialog object
        final Dialog dialog = new Dialog(this);

        // Include dialog.xml file
        dialog.setContentView(R.layout.dialog); // layout of your dialog

        ImageLoader imageLoader = AppController.getInstance().getImageLoader();
        NetworkImageView thumbnail1 = (NetworkImageView ) dialog.findViewById(R.id.gambar1);
        thumbnail1.setImageUrl(exerciseList.get(position).getGambar1(), imageLoader);


        // Set dialog title
        dialog.setTitle("Detail");

        // set values for custom dialog components - text, image and button
        TextView nama = (TextView) dialog.findViewById(R.id.nama);
        nama.setText("Nama = " + exerciseList.get(position).getNama());

        dialog.show();
    }
}

如果在 Fragment 中默认它运行完美并且没有问题，但是当我尝试使用 Activity 时所有数据都不会加载。

Answer 1

我看不到创建 Activity 时会运行的任何代码。您有一个 onCreateView 方法(我猜您是从基于 Fragment 的实现中继承过来的)。除非在您的代码中的某处(我看不到如何)调用该方法，否则它永远不会被调用，因为它不是 Activity 生命周期的一部分。我会将整个代码从该方法复制到 onCreate 方法(作为起点)并删除该方法。然后我会对前几行进行以下更改

// View rootView = inflater.inflate(R.layout.activity_list, container, false);
    // Noticed that I commented out the above line and changed the line below
    final ListView listView = (ListView) findViewById(R.id.list);

我并不是说这会解决您的所有问题，因为可能(可能)还有其他问题，但您应该是第一步。我强烈建议您更加熟悉 Activity 和 Fragment 类，并更加熟悉它们的生命周期。另外，你应该摆脱

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

祝你好运