Ошибка java.lang.NullPointerException при запуске фрагмента

Question

У меня есть вкладки с тремя различными фрагментами. Посещение, экзамен и результат. На некоторых телефонах, когда начинается фрагмент результата, приложение сообщает о сбоях.

java.lang.NullPointerException: Попытка вызвать виртуальный метод 'java.lang.Object android.content.Context.getSystemService (java.lang.String)' на нулевой ссылки на объект

вот LogCat

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference 
     at android.view.LayoutInflater.from(LayoutInflater.java:220) 
     at com.bu.innovate.bustudentportal.Result_Class$ExampleAdapter.<init>(Result_Class.java:886) 
     at com.bu.innovate.bustudentportal.Result_Class$results.onPostExecute(Result_Class.java:544) 
     at com.bu.innovate.bustudentportal.Result_Class$results.onPostExecute(Result_Class.java:245) 
     at android.os.AsyncTask.finish(AsyncTask.java:632) 
     at android.os.AsyncTask.access$600(AsyncTask.java:177) 
     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:145) 
     at android.app.ActivityThread.main(ActivityThread.java:5942) 
     at java.lang.reflect.Method.invoke(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:372) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195) 

и код его указывающий на это

public class Result_Class extends Fragment implements java.io.Serializable { 
    private AnimatedExpandableListView listView; 
    private ExampleAdapter adapter; 

    String url; 
    String url2; 
    String url3; 

    static String urladder = "Transcript.aspx"; 
    static String urladder2 = "Result.aspx"; 
    static String urladder3 = "Result_Exam.aspx"; 


    HashMap<String, String> hashMaps; 


    List<String> semester = new ArrayList<>(); 
    List<Result_Gdata> GPA = new ArrayList<>(); 
    List<Result_data> data_for_gra = new ArrayList<>(); 
    List<Result_data> loop_finder = new ArrayList<>(); 

    List<String> semester2 = new ArrayList<>(); 
    List<Result_Gdata> GPA2 = new ArrayList<>(); 
    List<Result_data> data_for_gra2 = new ArrayList<>(); 
    List<Result_data> loop_finder2 = new ArrayList<>(); 

    View rootview; 

    int num = 0; 

    HashMap<String, List<Result_data>> listDataChild; 


    FileOutputStream outputStream; 
    FileOutputStream outputStream2; 

    FileInputStream inputStream; 
    FileInputStream inputStream2; 

    String filename = "newResultData"; 
    String filename2 = "oldResultData"; 

    List<Result_data> data_for_gra3 = null; 
    List<String> semesters3 = null; 
    List<Result_data> loop_finder3 = null; 
    List<Result_Gdata> GPA3 = null; 


    List<Result_data> data_for_gra4 = null; 
    List<String> semesters4 = null; 
    List<Result_data> loop_finder4 = null; 
    List<Result_Gdata> GPA4 = null; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     super.onSaveInstanceState(savedInstanceState); 
     super.onCreate(savedInstanceState); 


     rootview = inflater.inflate(R.layout.anim_result_layout, container, false); 

     listView = (AnimatedExpandableListView) rootview.findViewById(R.id.listView); 
     hashMaps = Data.map; 

     listView.setDivider(null); 
     listView.setDividerHeight(0); 

     if (Data.mychoice == 1) { 
      num = 0; 
      Handler handler = new Handler(); 
      handler.postDelayed(new Runnable() { 
       @Override 
       public void run() { 
        new result_getter_second().execute(); 
       } 
      }, 1800); 

     } else { 
      Handler handlers2 = new Handler(); 
      handlers2.postDelayed(new Runnable() { 
       @Override 
       public void run() { 
        new results().execute(); 
       } 
      }, 2000); 
     } 
     return rootview; 

    } 

    private class result_getter_second extends AsyncTask<Void, Void, Void> { 


     @Override 
     protected void onPostExecute(Void aVoid) { 
      super.onPostExecute(aVoid); 

      num = 0; 

      listDataChild = new HashMap<>(); 

      List<GroupItem> items = new ArrayList<>(); 

      if (semester.size() != 0) { 
       for (int m = 0; m < semester.size(); m++) { 


        GroupItem item = new GroupItem(); 
        item.title = semester.get(m); 

        if (m < GPA.size()) { 
         item.gpa = GPA.get(m).getGPA(); 
         item.cgpa = GPA.get(m).getCGPA(); 
        } 


        List<Result_data> datw = new ArrayList<>(); 

        for (int n = num; n < loop_finder.get(m).getSize_of_the_result(); n++) { 
         ChildItem child = new ChildItem(); 
         child.course = data_for_gra.get(n).getSubject(); 
         child.grade = data_for_gra.get(n).getGrade(); 


         item.items.add(child); 


         datw.add(new Result_data(data_for_gra.get(n).getSubject(), data_for_gra.get(n).getGrade())); 
         num++; 
        } 

        items.add(item); 


        if(getActivity()!=null) 
        { 
         adapter = new ExampleAdapter(getActivity()); // line number 544 
         adapter.setData(items); 

         listView.setAdapter(adapter); 
        } 

        listView.setOnGroupClickListener(new OnGroupClickListener() { 

         @Override 
         public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) { 
          if (listView.isGroupExpanded(groupPosition)) { 

           listView.collapseGroupWithAnimation(groupPosition); 
          } else { 
           listView.expandGroupWithAnimation(groupPosition); 
          } 
          return true; 
         } 

        }); 

       } 
      } 

     } 

    } 

    private static class GroupItem { 
     String title; 
     String gpa; 
     String cgpa; 
     List<ChildItem> items = new ArrayList<ChildItem>(); 
    } 

    private static class ChildItem { 
     String course; 
     String grade; 
    } 

    private static class ChildHolder { 
     TextView course; 
     TextView grade; 
    } 

    private static class GroupHolder { 
     TextView title; 
     TextView gpa; 
     TextView cgpa; 
    } 

    /** 
    * Adapter for our list of {@link GroupItem}s. 
    */ 
    private class ExampleAdapter extends AnimatedExpandableListView.AnimatedExpandableListAdapter { 
     private LayoutInflater inflater; 

     private List<GroupItem> items; 

     public ExampleAdapter(Context context) { 
      if(context!=null) 
      { 
       inflater = LayoutInflater.from(context); // line number 886 
      } 
     } 

     public void setData(List<GroupItem> items) { 
      this.items = items; 
     } 

     @Override 
     public ChildItem getChild(int groupPosition, int childPosition) { 
      return items.get(groupPosition).items.get(childPosition); 
     } 

     @Override 
     public long getChildId(int groupPosition, int childPosition) { 
      return childPosition; 
     } 

     @Override 
     public View getRealChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) { 
      ChildHolder holder; 
      ChildItem item = getChild(groupPosition, childPosition); 
      if (childPosition == 0) { 
       holder = new ChildHolder(); 
       convertView = inflater.inflate(R.layout.anim_list_item_result, parent, false); 
       holder.course = (TextView) convertView.findViewById(R.id.textcourse); 
       holder.grade = (TextView) convertView.findViewById(R.id.textgrade); 
       convertView.setTag(holder); 
       holder.course.setText(item.course); 
       holder.grade.setText(item.grade); 
      } else if (isLastChild) { 
       holder = new ChildHolder(); 
       convertView = inflater.inflate(R.layout.anim_list_item_result_last_child, parent, false); 
       holder.course = (TextView) convertView.findViewById(R.id.textcourse); 
       holder.grade = (TextView) convertView.findViewById(R.id.textgrade); 
       convertView.setTag(holder); 
       holder.course.setText(item.course); 
       holder.grade.setText(item.grade); 
      } else { 
       holder = new ChildHolder(); 
       convertView = inflater.inflate(R.layout.anim_list_item_result_middle, parent, false); 
       holder.course = (TextView) convertView.findViewById(R.id.textcourse); 
       holder.grade = (TextView) convertView.findViewById(R.id.textgrade); 
       convertView.setTag(holder); 
       holder.course.setText(item.course); 
       holder.grade.setText(item.grade); 
      } 


      return convertView; 
     } 

     @Override 
     public int getRealChildrenCount(int groupPosition) { 
      return items.get(groupPosition).items.size(); 
     } 

     @Override 
     public GroupItem getGroup(int groupPosition) { 
      return items.get(groupPosition); 
     } 

     @Override 
     public int getGroupCount() { 
      return items.size(); 
     } 

     @Override 
     public long getGroupId(int groupPosition) { 
      return groupPosition; 
     } 

     @Override 
     public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) { 
      GroupHolder holder; 
      GroupItem item = getGroup(groupPosition); 


      if (groupPosition == getGroupCount() - 1) { 

       holder = new GroupHolder(); 
       convertView = inflater.inflate(R.layout.anim_group_item_result_last_child, parent, false); 
       holder.title = (TextView) convertView.findViewById(R.id.textTitle); 
       holder.gpa = (TextView) convertView.findViewById(R.id.textgpa); 
       holder.cgpa = (TextView) convertView.findViewById(R.id.textcgpa); 
       convertView.setTag(holder); 


       holder.title.setText(item.title); 
       holder.gpa.setText(item.gpa); 
       holder.cgpa.setText(item.cgpa); 
      } else { 
       holder = new GroupHolder(); 
       convertView = inflater.inflate(R.layout.anim_group_item_result, parent, false); 
       holder.title = (TextView) convertView.findViewById(R.id.textTitle); 
       holder.gpa = (TextView) convertView.findViewById(R.id.textgpa); 
       holder.cgpa = (TextView) convertView.findViewById(R.id.textcgpa); 
       convertView.setTag(holder); 


       holder.title.setText(item.title); 
       holder.gpa.setText(item.gpa); 
       holder.cgpa.setText(item.cgpa); 

      } 

      if (groupPosition == 0) { 
       ExpandableListView elv = (ExpandableListView) parent; 
       elv.expandGroup(groupPosition); 
      } 

      return convertView; 
     } 

     @Override 
     public boolean hasStableIds() { 
      return true; 
     } 

     @Override 
     public boolean isChildSelectable(int arg0, int arg1) { 
      return true; 
     } 

    } 

    private boolean isOnline() { 
     ConnectivityManager cm = (ConnectivityManager) getContext().getSystemService(Context.CONNECTIVITY_SERVICE); 
     NetworkInfo netInfo = cm.getActiveNetworkInfo(); 
     //should check null because in air plan mode it will be null 
     return (netInfo != null && netInfo.isConnected()); 
    } 
} 

Проблема в первой строке, где называется getcontext(). Я так много пытался решить эту проблему, но не смог. Было бы очень полезно Если вы, ребята, поможете мне решить эту проблему.

Answer 1

Вы делаете это onCreate in fragment? !

Добавить проверка getContext() = нуль

Перед блок

adapter = new ExampleAdapter(getContext()); 
adapter.setData(items); 
listView.setAdapter(adapter); 

И лучше заменить на getActivity() = нуль

Например:

if (getActivity()!=null){ 
    adapter = new ExampleAdapter(getActivity()); 
    adapter.setData(items); 
    listView.setAdapter(adapter); 
}