android - 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' 在通知通知 Android 时在空对象引用上

Question

所以，我试图运行我的应用程序，它应该在第一次运行后显示通知。但是，它给了我这样的错误:

java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.app.Notification$Builder.<init>(Notification.java:1951)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.support.v4.app.NotificationCompatApi21$Builder.<init>(NotificationCompatApi21.java:68)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.support.v4.app.NotificationCompat$NotificationCompatImplApi21.build(NotificationCompat.java:759)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.support.v4.app.NotificationCompat$Builder.build(NotificationCompat.java:1559)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at apps.skripsi.petvac.navigationmenu.MainMenu.createButtonNotification(MainMenu.java:383)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at apps.skripsi.petvac.navigationmenu.MainMenu$DataBinatangOperation.onPostExecute(MainMenu.java:235)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at apps.skripsi.petvac.navigationmenu.MainMenu$DataBinatangOperation.onPostExecute(MainMenu.java:145)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.os.AsyncTask.finish(AsyncTask.java:632)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.os.AsyncTask.access$600(AsyncTask.java:177)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:102)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:135)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5253)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:372)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:900)
12-10 12:01:03.512 3132-3132/apps.skripsi.petvac E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:695)

这是我的完整代码

package apps.skripsi.petvac.navigationmenu;


import android.app.Activity;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.support.v4.app.NotificationCompat;
import android.support.v4.app.TaskStackBuilder;
import android.support.v4.widget.SwipeRefreshLayout;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import org.apache.http.client.ClientProtocolException;
import org.joda.time.DateTime;
import org.joda.time.Days;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Locale;

import apps.skripsi.petvac.MainMenu.MainMenuAdapter;
import apps.skripsi.petvac.R;
import apps.skripsi.petvac.addpetdata.MainAddPetDataActivity;
import apps.skripsi.petvac.Services.NotificationHandler;
import apps.skripsi.petvac.notification.NotificationButtonReceiver;
import apps.skripsi.petvac.notification.TestActivity;
import apps.skripsi.petvac.parser.JSONParser;
import apps.skripsi.petvac.petinformation.MainPetInformation;
import apps.skripsi.petvac.preference.PreferencesHelper;

/**
 * Created by widi on 9/9/2015.
 */
public class MainMenu extends Fragment {

    FloatingActionButton FAB;
    JSONObject json;
    JSONObject jsonObject;
    PreferencesHelper pref;
    ProgressDialog loading;
    NotificationHandler NH;
    ImageView iv;
    ProgressDialog progress;
    NotificationManager mNotificationManager;
    SwipeRefreshLayout mSwipeRefreshLayout = null;
    ListView list;
    TextView tv;
    String result;
    String sisaWaktu;
    String ID_USER, ID_BINATANG, NAMA_BINATANG, JENIS_BINATANG, FOTO_BINATANG, RAS_BINATANG, TANGGAL_VAKSIN, NAMA_VAKSIN, ID_DATA_WAKTU_VAKSINASI;

    ArrayList<HashMap<String, String>> listBinatang = new ArrayList<HashMap<String, String>>();

    public static String id_user = "id_user";
    public static String id_binatang = "id_binatang";
    public static String nama_binatang = "nama_binatang";
    public static String jenis_binatang = "jenis_binatang";
    public static String foto_binatang = "foto_binatang";
    public static String ras_binatang = "ras_binatang";
    public static String tanggal_vaksin = "tanggal_awal";
    public static String nama_vaksin = "nama_vaksin";
    public static String id_data_waktu_vaksinasi = "id_data_waktu_vaksinasi";

    private Context context;

    private static String url = "http://petvaccination.hol.es/api/data_menu_utama_vaksinasi.php";

    private static String urlgambar = "http://petvaccination.hol.es/imgupload/uploadedimages/";

    public MainMenu() {
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.main_menu_fragment, container, false);

        FAB = (FloatingActionButton) v.findViewById(R.id.buttonTambahData);

        mSwipeRefreshLayout = (SwipeRefreshLayout) v.findViewById(R.id.activity_main_swipe_refresh_layout);




        pref = new PreferencesHelper(getActivity().getBaseContext());

        tv = (TextView) v.findViewById(R.id.textView);

        list = (ListView) v.findViewById(R.id.list_hewan);

        NH = NotificationHandler.getInstance(getActivity());

        FAB.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent a = new Intent(getActivity(), MainAddPetDataActivity.class);
                startActivity(a);
            }
        });


        new DataBinatangOperation().execute(url);

        mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                new DataBinatangOperation().execute(url);
                updateList();
            }
        });


        return v;
    }

    private void updateList() {

        if (mSwipeRefreshLayout.isRefreshing()) {
            mSwipeRefreshLayout.setRefreshing(false);
        }
    }


    private class DataBinatangOperation extends AsyncTask<String, Void, String> {

        MainMenuAdapter adapter = new MainMenuAdapter(MainMenu.this,
                listBinatang);

        @Override
        protected String doInBackground(String... params) {

            JSONArray json;
            try {
                result = JSONParser.getPage(url);
            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }


            return result;
        }


        @Override
        protected void onPostExecute(String result) {

            //updateList();
            tv.setVisibility(View.GONE);

            //mSwipeRefreshLayout.setRefreshing(false);


            try {
                System.out.print("result = " + result);
                json = new JSONObject(result);
                progress.dismiss();

                JSONArray objek = json.getJSONArray("data_vaksinasi_menu");

                for (int i = 0; i < objek.length(); i++) {

                    JSONObject jo = objek.getJSONObject(i);

                    ID_USER = jo.getString(id_user);
                    ID_BINATANG = jo.getString(id_binatang);
                    NAMA_BINATANG = jo.getString(nama_binatang);
                    JENIS_BINATANG = jo.getString(jenis_binatang);
                    FOTO_BINATANG = jo.getString(foto_binatang);
                    RAS_BINATANG = jo.getString(ras_binatang);
                    ID_DATA_WAKTU_VAKSINASI = jo.getString(id_data_waktu_vaksinasi);
                    TANGGAL_VAKSIN = jo.getString(tanggal_vaksin);
                    NAMA_VAKSIN = jo.getString(nama_vaksin);
                    if (pref.getPreferences("ID").equals(ID_USER)) {

                        if (jo.isNull(id_data_waktu_vaksinasi) && jo.isNull(tanggal_vaksin)  && jo.isNull(nama_vaksin)) {
                            NAMA_VAKSIN = "belum ada data";
                            sisaWaktu = "";
                        }else {

                            DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());

                            Calendar waktuSekarang = Calendar.getInstance();

                            Date date1 = waktuSekarang.getTime();
                            Date date2 = new Date();

                            date2 = formatter.parse(TANGGAL_VAKSIN);


                            if (date2.after(date1)) {
                                int days = Days.daysBetween(new DateTime(date1), new DateTime(date2)).getDays();
                                if (days > 7 && days <= 30) {
                                    int weeks = days / 7;
                                    sisaWaktu = String.valueOf(weeks) + " minggu";
                                } else if (days > 30 && days <= 365) {
                                    int months = days / 30;
                                    sisaWaktu = String.valueOf(months) + " bulan";
                                } else if (days > 365) {
                                    int years = days / 365;
                                    sisaWaktu = String.valueOf(years) + " tahun";
                                } else {
                                    sisaWaktu = String.valueOf(days) + " hari";
                                    if (days <= 5) {
                                        createSimpleNotification(getActivity(), NAMA_BINATANG, sisaWaktu, ID_BINATANG);
                                    }
                                }
                            } else if (date2.before(date1)) {
                                int days = Days.daysBetween(new DateTime(date2), new DateTime(date1)).getDays();
                                sisaWaktu = "lewat " + String.valueOf(days) + " hari";
                                createButtonNotification(context, NAMA_BINATANG, sisaWaktu, ID_BINATANG, ID_DATA_WAKTU_VAKSINASI);

                            } else if (date2.equals(date1)) {
                                sisaWaktu = "sekarang";
                                createButtonNotification(context, NAMA_BINATANG, sisaWaktu, ID_BINATANG, ID_DATA_WAKTU_VAKSINASI);
                            }

                        }

                    }

                    HashMap<String, String> map = new HashMap<String, String>();

                    map.put(id_binatang, ID_BINATANG);
                    map.put(nama_binatang, NAMA_BINATANG);
                    map.put(jenis_binatang, JENIS_BINATANG);
                    map.put(foto_binatang, urlgambar + FOTO_BINATANG);
                    map.put(ras_binatang, RAS_BINATANG);
                    map.put(tanggal_vaksin, sisaWaktu);
                    map.put(nama_vaksin, NAMA_VAKSIN);


                    if (pref.getPreferences("ID").equals(ID_USER)) {
                        listBinatang.add(map);
                    }


                }

                if(String.valueOf(listBinatang).equals("[]")){
                    tv.setVisibility(View.VISIBLE);
                }

                System.out.println("hasil list : " + String.valueOf(listBinatang));

                System.out.println("adapter : " + String.valueOf(adapter));
                list.setAdapter(adapter);



                /*list.setVisibility(View.VISIBLE);*/
                list.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                    @Override
                    public void onItemClick(AdapterView<?> parent, View view,
                                            int position, long idx) {

                        HashMap<String, String> ambilid = new HashMap<String, String>();
                        ambilid = listBinatang.get(position);

                        Toast.makeText(getActivity(), "pindah halaman", Toast.LENGTH_SHORT).show();

                        Intent a = new Intent(getActivity(), MainPetInformation.class);
                        pref.savePreferences("IDB", ambilid.get(MainMenu.id_binatang));
                        pref.savePreferences("NAMAB", ambilid.get(MainMenu.nama_binatang));
                        pref.savePreferences("FOTOB", ambilid.get(MainMenu.foto_binatang));
                        pref.savePreferences("JENISB", ambilid.get(MainMenu.jenis_binatang));
                        pref.savePreferences("RASB", ambilid.get(MainMenu.ras_binatang));
                        startActivity(a);
                    }

                });

            } catch (JSONException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (ParseException e) {
                e.printStackTrace();
            }

            // might want to change "executed" for the returned string passed
            // into onPostExecute() but that is upto you
        }

        @Override
        protected void onPreExecute() {
            listBinatang.clear();
            adapter.notifyDataSetChanged();
            progress = ProgressDialog.show(getActivity(), "Please Wait",
                    "Loading Data", true);

        }

        @Override
        protected void onProgressUpdate(Void... values) {
        }
    }

    public void createSimpleNotification(Context context, String title, String content, String id) {
        // Creates an explicit intent for an Activity
        Intent resultIntent = new Intent(context, MainPetInformation.class);
        resultIntent.putExtra("id", id);
        context.startActivity(resultIntent);

        mNotificationManager = (NotificationManager)context.getSystemService(getActivity().NOTIFICATION_SERVICE);

        int IntID = Integer.valueOf(id);

        Uri uri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        // Creating a artifical activity stack for the notification activity
        TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
        stackBuilder.addParentStack(TestActivity.class);
        stackBuilder.addNextIntent(resultIntent);

        // Pending intent to the notification manager
        PendingIntent resultPending = PendingIntent.getActivity(context, IntID, resultIntent, 0);


        // Building the notification
        NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(context)
                .setSmallIcon(R.drawable.logo) // notification icon
                .setContentTitle(title) // main title of the notification
                .setContentText(content + " lagi")
                .setSound(uri) // notification text
                .setContentIntent(resultPending);// notification intent


        // mId allows you to update the notification later on.
        mNotificationManager.notify(IntID, mBuilder.build());
    }

    public void createButtonNotification(Context context, String title, String content, String idb, String idv) {
        // Prepare intent which is triggered if the  notification button is pressed

        Log.d("idb", idb);
        Intent intent = new Intent(getActivity(), MainPetInformation.class);
        intent.putExtra("IDBIN", idb);
        intent.putExtra("IDVAK", idv);

        mNotificationManager = (NotificationManager)context.getSystemService(getActivity().NOTIFICATION_SERVICE);

        Uri uri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);

        int IntID = Integer.valueOf(idb);

        PendingIntent IntentAccept = PendingIntent.getActivity(getActivity(), IntID, intent, 0);

        PendingIntent IntentCancel = PendingIntent.getActivity(getActivity(), IntID, intent, 0);


        // Building the notifcation
        NotificationCompat.Builder nBuilder = new NotificationCompat.Builder(context)
                .setSmallIcon(R.drawable.logo) // notification icon
                .setContentTitle(title) // notification title
                .setContentText(content)
                .setSound(uri)// content text
                .addAction(R.drawable.accept, "Accept", IntentAccept) // accept notification button
                .addAction(R.drawable.cancel, "Cancel", IntentCancel); // cancel notification button


        mNotificationManager.notify(IntID, nBuilder.build());


    }


}

错误表明它发生在这一行:

mNotificationManager.notify(IntID, nBuilder.build());

请帮忙:(

Answer 1

由于尝试在 onCreate 方法之外设置 contentView，我遇到了这个问题。
我在 kotlin 中执行此操作，但忘记使用 by lazy