AsyncTask detecting if done

Question

I have created an AsyncTask that loads data from a website then when I execute it. At the moment I'm getting a null pointer exception which I think is caused because I'm trying to fill the UI too early so I'm hoping to create some kind of if statement that says if AsyncTask isn't complete show a loading graphic and when it is fill the data. But I'm not sure how to go about doing this does anyone know how I could achieve this or at least point me in the right direction.

Here's my code so far

public void checkPreferences(){

    SharedPreferences preferences = getSharedPreferences("prefs", Context.MODE_PRIVATE);
    ChosenMethod = preferences.getString("ChosenMethod", ChosenMethod);
    ChosenLeagueID = preferences.getString("ChosenLeagueId", ChosenLeagueID);
    ChosenTeamId = preferences.getString("ChosenTeamId", ChosenTeamId);

    Log.v("lc", "newsurl" + newsFeedURL);


    Log.v("myapp", "ChosenMethod Home = " + ChosenMethod);
    Log.v("myapp", "ChosenLeagueID Home = " + ChosenLeagueID);
    Log.v("myapp", "ChosenTeamID Home = " + ChosenTeamId);

    if (ChosenMethod.equals("Team")) {
        setContentView(R.layout.homeactteam2);
        newsAmount = 5;

    } else {
        newsAmount = 10;
        setContentView(R.layout.homeactteam);
    }

}


@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    //Check Preferences which sets UI

    checkPreferences();
   PostTask posttask;
   posttask = new PostTask();
   posttask.execute();

   FillData();


    Button backbtn = (Button) findViewById(R.id.backbtn);

    //Listening to button event
    backbtn.setOnClickListener(new View.OnClickListener() {

        public void onClick(View arg0) {
            //Starting a new Intent
            Intent previousScreen = new Intent(getApplicationContext(), ChooseTeamActivity.class);
            ChosenMethod = "null";
            SharedPreferences preferences = getSharedPreferences("prefs", Context.MODE_PRIVATE);
            SharedPreferences.Editor editor = preferences.edit();
            editor.putString("ChosenMethod", ChosenMethod);            
            editor.commit();
            previousScreen.putExtra("FullData", fulldata);
            startActivity(previousScreen);


        }
    });

//((PullToRefreshListView) getListView()).setOnRefreshListener(new OnRefreshListener() {
//   
//    public void onRefresh() {
//        // Do work to refresh the list here.
//        loadData();
//    }
//});
//


}



public void loadNewsFeed(){

     newsFeedRequest = "website/" + chosenLeagueId + "/news?timestamp=" + unixTimeStamp;
     newsFeedURL = "https://www.website.com" + newsFeedRequest; 

        String myhash = buildHmacSignature(apiKey, newsFeedURL);
        HttpClient client = new DefaultHttpClient();
        HttpPost post = new HttpPost(newsFeedURL);

        List<NameValuePair> pairs = new ArrayList<NameValuePair>();
        pairs.add(new BasicNameValuePair("requestToken", myhash));
        pairs.add(new BasicNameValuePair("apiUser", apiUser));

            try {
                post.setEntity (new UrlEncodedFormEntity(pairs));
                HttpResponse response = client.execute(post);
                BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8"));
                String json = reader.readLine();
                fulldata = String.valueOf(json);
                Log.v("myApp","newsdata" + fulldata);

                newsList = new ArrayList<String>();
                newsList2 = new ArrayList<String>();
                newsList3 = new ArrayList<String>();
                imageList = new ArrayList<String>();


                JSONObject obj = new JSONObject(json);    
                JSONObject objData = obj.getJSONObject("data");
                JSONArray jArray = objData.getJSONArray("news");
                Log.v("lc","newsAmount= " + newsAmount);

                   for(int t = 0; t < newsAmount; t++){
                       JSONObject newsTitleDict = jArray.getJSONObject(t);
                       imageList.add(newsTitleDict.getString("image_small"));
                     newsList3.add(newsTitleDict.getString("title"));

                   }

                   for(int t = 0; t < 1; t++){
                       JSONObject newsTitleDict = jArray.getJSONObject(t);

                 newsList.add(newsTitleDict.getString("title"));
            //       newsList2.add(newsTitleDict.getString("title"));

                   }



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


}           


public void loadResultsFeed(){


    resultsFeedRequest = "website/" + chosenLeagueId + "/results?&team_id=" + ChosenTeamId + "&limit=31&timestamp=" + unixTimeStamp;
    resultsFeedURL = "https://www.website.com" + resultsFeedRequest;    

    String myhash = buildHmacSignature(apiKey, resultsFeedURL);

    HttpClient client = new DefaultHttpClient();
    HttpPost post = new HttpPost(resultsFeedURL);

    List<NameValuePair> pairs = new ArrayList<NameValuePair>();
    pairs.add(new BasicNameValuePair("requestToken", myhash));
    pairs.add(new BasicNameValuePair("apiUser", apiUser));

    try {
        post.setEntity (new UrlEncodedFormEntity(pairs));
        HttpResponse response = client.execute(post);
        BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8"));
        String json = reader.readLine();
        fulldata = String.valueOf(json);
        Log.v("myApp","resultsdata" + fulldata);

        newsList = new ArrayList<String>();
        newsList2 = new ArrayList<String>();
        newsList3 = new ArrayList<String>();
        imageList = new ArrayList<String>();


        JSONObject obj = new JSONObject(json);    
        JSONObject objData = obj.getJSONObject("data");
        JSONArray jArray = objData.getJSONArray("results");


        if(jArray.length() < 1) loadLastResults();



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


}


public void loadLastResults(){

    resultsFeedRequest = "website/" + chosenLeagueId + "/results?month=04&team_id=" + ChosenTeamId + "&limit=31&timestamp=" + unixTimeStamp;
    resultsFeedURL = "https://www.website.com" + resultsFeedRequest;    

     String myhash = buildHmacSignature(apiKey, resultsFeedURL);

    Date anotherCurDate = new Date();  
    SimpleDateFormat formatter = new SimpleDateFormat("MM");  
    String CurMonth = formatter.format(anotherCurDate);  

    int Int = Integer.parseInt(CurMonth);

    int MonthInt = Int -1;


    CurMonth = (String) (String.valueOf(MonthInt));



    if (CurMonth.equals("1")){

        lastMonth = "12";

    }    
     else {
        if(CurMonth.length() < 2){
            lastMonth = "0" + CurMonth;
        } else {
            lastMonth = CurMonth;
        }
    }

    Log.v("lc","month= " + CurMonth);
    Log.v("lc","LastMonth= " + lastMonth);


        HttpClient client = new DefaultHttpClient();
        HttpPost post = new HttpPost(resultsFeedURL);

        List<NameValuePair> pairs = new ArrayList<NameValuePair>();
        pairs.add(new BasicNameValuePair("requestToken", myhash));
        pairs.add(new BasicNameValuePair("apiUser", apiUser));

        try {
            post.setEntity (new UrlEncodedFormEntity(pairs));
            HttpResponse response = client.execute(post);
            BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8"));
            String json = reader.readLine();
            fulldata = String.valueOf(json);
            Log.v("myApp","resultsdata" + fulldata);

            newsList = new ArrayList<String>();
            newsList2 = new ArrayList<String>();
            newsList3 = new ArrayList<String>();
            imageList = new ArrayList<String>();


            JSONObject obj = new JSONObject(json);    
            JSONObject objData = obj.getJSONObject("data");
            JSONArray jArray = objData.getJSONArray("results");


               for(int t = 0; t < 1; t++){

                   resultsDict = jArray.getJSONObject(t);
                  HomeTeam = resultsDict.getString("hometeam");
                  AwayTeam = resultsDict.getString("awayteam");
                  HomeScore = resultsDict.getString("homescore");
                  AwayScore = resultsDict.getString("awayscore");
                  Attendance = resultsDict.getString("attendance");
                  Division = resultsDict.getString("division");

                  Log.v("lc","hometeam" + HomeTeam);
                  Log.v("lc","awayteam" + AwayTeam);


               }


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


    }   


public class PostTask extends AsyncTask<Void, String, Boolean> {

    @Override
    protected Boolean doInBackground(Void... params) {
        boolean result = false;
        loadNewsFeed();
        loadResultsFeed();
        loadLastResults();
        publishProgress("progress");
        return result;
    }

    protected void onProgressUpdate(String... progress) {
        StringBuilder str = new StringBuilder();
            for (int i = 1; i < progress.length; i++) {
                str.append(progress[i] + " ");
            }
    }

}

public void FillData(){ 


     if (ChosenMethod.equals("Team")) {


         resultsView = LayoutInflater.from(getBaseContext()).inflate(R.layout.resultscell,
                 null);

       TextView homeTeam = (TextView) resultsView.findViewById(R.id.HomeTeam);
       homeTeam.setText(HomeTeam);

       TextView awayTeam = (TextView) resultsView.findViewById(R.id.AwayTeam);
       awayTeam.setText(AwayTeam);

       TextView homeScore = (TextView) resultsView.findViewById(R.id.HomeScore);
       homeScore.setText(HomeScore);

       TextView awayScore = (TextView) resultsView.findViewById(R.id.AwayScore);
       awayScore.setText(AwayScore);

       TextView attendance = (TextView) resultsView.findViewById(R.id.Attendence);
       attendance.setText("Att:" + Attendance);

       TextView division = (TextView) resultsView.findViewById(R.id.Division);
       division.setText(Division);

        arrayAdapter = new ArrayAdapter<String>(this, R.layout.single_item, newsList);

         String[] mStrings = (String[]) imageList.toArray(new String[imageList.size()]);
         String[] news = (String[]) newsList3.toArray(new String[newsList3.size()]);

         arrayAdapter3 = new LazyAdapter(this, mStrings, news);


            ListView list = getListView();
               list.setTextFilterEnabled(true);

               LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE );
                View header = inflater.inflate( R.layout.homeheader, list, false);
                View header2 = inflater.inflate( R.layout.homeheader2, list, false);
                View header3 = inflater.inflate( R.layout.homeheader3, list, false);


        //setListAdapter (arrayAdapter);


            adapter = new MergeAdapter();
            adapter.addView(header);
            adapter.addAdapter(arrayAdapter);
            adapter.addView(header2);
            adapter.addView(resultsView);
            adapter.addView(header3);
            adapter.addAdapter(arrayAdapter3);
            setListAdapter(adapter);



     } else {

         arrayAdapter = new ArrayAdapter<String>(this, R.layout.single_item, newsList);
            arrayAdapter2 = new ArrayAdapter<String>(this, R.layout.single_item, newsList2);
            //arrayAdapter3 = new ArrayAdapter(this, R.layout.complex_item, newsList3);

             String[] mStrings = (String[]) imageList.toArray(new String[imageList.size()]);
             String[] news = (String[]) newsList3.toArray(new String[newsList3.size()]);


             arrayAdapter3 = new LazyAdapter(this, mStrings, news);


                ListView list = getListView();
                   list.setTextFilterEnabled(true);

                   LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE );
                    View header3 = inflater.inflate( R.layout.homeheader3, list, false);


            //setListAdapter (arrayAdapter);


                adapter = new MergeAdapter();
                adapter.addView(header3);
                adapter.addAdapter(arrayAdapter3);
                setListAdapter(adapter);
         } 
}

Answer 1

Blindly Assumption...! (Without StackTrace report)

Implement onPostExecute() in your AsyncTask and put FillData() method in it.. When your doInBackground().. completes control comes in onPostExecute() automatically.. Then fill your UI part..

Answer 2

call your FillData() method inside onPostExecute Method of AsyncTask

it should be::

public class PostTask extends AsyncTask<Void, String, Boolean> {

    @Override
    protected Boolean doInBackground(Void... params) {
        boolean result = false;
        loadNewsFeed();
        loadResultsFeed();
        loadLastResults();
        publishProgress("progress");
        return result;
    }


    protected void onProgressUpdate(String... progress) {
        StringBuilder str = new StringBuilder();
            for (int i = 1; i < progress.length; i++) {
                str.append(progress[i] + " ");
            }
    }

        @Override
    protected void onPostExecute(Boolean result) {
        super.onPostExecute(result);

         fillData();
    }
}

Answer 3

Add a method in asynctask i.e

public void onPostExecute(Void result){} 

And in it dismiss the dialogue and call your fillData()

Answer 4

You should use another method of AsyncTask for updating UI.

protected void onPostExecute(Long result) {
    showDialog("Downloaded " + result + " bytes");
}

Answer 5

You can use a ProgressDialog till the complete data from server comes to your end and fill the data...

Please read this.

Let me know if have any issue.

Thanks,

Haps.