비동기 작업의 데이터로 스피너 업데이트

Question

응용 프로그램을 시작하면 조각의 스피너에 데이터베이스의 데이터가 채워집니다. 데이터베이스에서 문자열 목록을 가져 와서 스피너에 표시하려고합니다. 채울 목록이 있고 ArrayAdapter는 PostExecute에서 변경되지만 아무 것도 표시되지 않을 때 변경됩니다.

조각 코드

public static class RegisterFragment extends Fragment{ 


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

    List<String> instituteList = new ArrayList<String>(); 
    View rootView = inflater.inflate(R.layout.fragment_register, container, false); 
    if (instituteList.isEmpty()){ //list is null on app start-up 
     Log.d("test","null list"); 
    }else{ 

    Spinner autoInstitute = (Spinner)getActivity(). findViewById(R.id.institute); 
// Get the string array 
    String[] institutes = (String[]) instituteList.toArray(new String[instituteList.size()]);; 
// Create the adapter and set it to the AutoCompleteTextView 
ArrayAdapter<String> instituteApapdter = 
     new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, institutes); 
instituteApapdter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
    autoInstitute.setAdapter(instituteApapdter); 
    } 
     return rootView; 
} 

비동기 클래스

class getInstitute extends AsyncTask<String, String, String>{ 

    @Override 
    protected void onPreExecute() { 

     super.onPreExecute(); 
     pDialog = new ProgressDialog(Login.this); 
     pDialog.setMessage("Loading Institute List"); 
     pDialog.setIndeterminate(false); 
     pDialog.setCancelable(true); 
     pDialog.show(); 

    } 
    @Override 
    protected String doInBackground(String... params) { 
        //Get data and store in List 
    } 
protected void onPostExecute(String file_url) { 
     // dismiss the dialog once done 
     pDialog.dismiss(); 
     institutes_array = (String[]) instituteList.toArray(new String[instituteList.size()]);; 
     final ArrayAdapter<String> instituteApapdter = 
       new ArrayAdapter<String>(Login.this, android.R.layout.simple_list_item_1, institutes_array); 
     instituteApapdter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
     runOnUiThread(new Runnable() { 

      public void run() { 

       instituteApapdter.notifyDataSetChanged(); 
      } 
     //autoInstitute.setAdapter(instituteApapdter); // causes nullpointerexception 
     }); 
    } 

Answer 1

쓰기이 :

이 대신

Spinner autoInstitute = (Spinner)rootView. findViewById(R.id.institute); 

:

Spinner autoInstitute = (Spinner)getActivity(). findViewById(R.id.institute); 

,536,

또한 AsyncTask 클래스에서 ArrayAdapter() 생성자의 첫 번째 인수로 Login.this을 작성했습니다. getActivity()

이 있어야한다 완전한 RegisterFragment 클래스를 변경 :

package com.bhavit.stackoverflow; 

public static class RegisterFragment extends Fragment{ 

    Spinner autoInstitute; 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
       Bundle savedInstanceState) { 

     List<String> instituteList = new ArrayList<String>(); 
     View rootView = inflater.inflate(R.layout.fragment_register, container, false); 

     if (instituteList.isEmpty()){ //list is null on app start-up 
      Log.d("test","null list"); 
     }else{ 

     autoInstitute = (Spinner)getActivity(). findViewById(R.id.institute); 

     GetInstitute obj = new GetInstitute(); 
     obj.execute(); 


     } 
      return rootView; 
    } 


    class GetInstitute extends AsyncTask<String, String, String>{ 

      @Override 
      protected void onPreExecute() { 

       super.onPreExecute(); 
       pDialog = new ProgressDialog(getActivity()); 
       pDialog.setMessage("Loading Institute List"); 
       pDialog.setIndeterminate(false); 
       pDialog.setCancelable(true); 
       pDialog.show(); 

      } 
      @Override 
      protected String doInBackground(String... params) { 
          //Get data and store in List 
      } 
     protected void onPostExecute(String file_url) { 
       // dismiss the dialog once done 
       pDialog.dismiss(); 
       institutes_array = (String[]) instituteList.toArray(new String[instituteList.size()]);; 
       final ArrayAdapter<String> instituteApapdter = 
         new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, institutes_array); 
       instituteApapdter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 

        instituteApapdter.notifyDataSetChanged(); 

      autoInstitute.setAdapter(instituteApapdter); // causes nullpointerexception 

      } 
    } 

}