CODEWITHSUNDEEP
androidandroid-asynctask
Luke Batley
Luke Batley

Reputation: 2402

Android how to integrate an AsyncTask

Hi I have an app that downloads a JSON feed and its starting to become leggy I know I need to use AsyncTask it but I'm not sure how to integrate that into my code does anyone know whats the best way to integrate it.

heres my original code so far

public class HomeActivity extends ListActivity {

    private MergeAdapter adapter=null;
    private ArrayAdapter<String> arrayAdapter=null;
    private ArrayAdapter<String> arrayAdapter2=null;
    private LazyAdapter arrayAdapter3=null;
    private static final String apiKey = "7668hhf74hhd3dhhs"; 
    private static final String apiUser = "androiduser";
    private static String ChosenLeagueID = null;
    private static String ChosenMethod = null; 
    private static String ChosenTeamId = null; 
    public String fulldata = null;
    public String newsFeedRequest = null;
    public String newsFeedURL = null;
    public String resultsFeedURL = null;
    public String lastMonth = null;
    public String HomeTeam = null;
    public String AwayTeam = null;
    public String HomeScore = null;
    public String AwayScore = null;
    public String Attendance = null;
    public String Division = null;
    public String HomeScorers = null;
    public String AwayScorers = null;       

    public String resultsFeedRequest = null;
    public String chosenLeagueId = "40";
    public List<String> newsList = null;
    public List<String> newsList2 = null;
    public List<String> newsList3 = null;
    public List<String> imageList = null;
    public JSONObject resultsDict = null;
    public View resultsView = null;



    public int newsAmount = 0;

    long unixTimeStamp = System.currentTimeMillis() / 1000L;

    //add Time Stamp to URL
    //public String chosenMethod; 
    public class PostTask extends AsyncTask<Void, String, Boolean> {

        @Override
        protected Boolean doInBackground(Void... params) {
            boolean result = false;
         checkPreferences();


            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] + " ");
                }

        }

    }

    static String buildHmacSignature(String pKey, String pStringToSign)
    {
      String lSignature = "None";
      try
      {
        Mac lMac = Mac.getInstance("HmacSHA256");
        SecretKeySpec lSecret = new SecretKeySpec(pKey.getBytes(), "HmacSHA256");
        lMac.init(lSecret);

        byte[] lDigest = lMac.doFinal(pStringToSign.getBytes());
        BigInteger lHash = new BigInteger(1, lDigest);
        lSignature = lHash.toString(16);
        if ((lSignature.length() % 2) != 0) {
          lSignature = "0" + lSignature;
        }
      }
      catch (NoSuchAlgorithmException lEx)
      {
        throw new RuntimeException("Problems calculating HMAC", lEx);
      }
      catch (InvalidKeyException lEx)
      {
        throw new RuntimeException("Problems calculating HMAC", lEx);
      }

      return lSignature;
    }





    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;
             loadData();



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

}


    public void loadresults(){

    resultsFeedRequest = "1.0/league-website/" + chosenLeagueId + "/results?&team_id=" + ChosenTeamId + "&limit=31&timestamp=" + unixTimeStamp;
    resultsFeedURL = "https://www.website.com/_services/api/" + 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();

        }else{

            Log.v("lc", "this month has results");

        }


//      
//         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 loadLastResults(){

resultsFeedRequest = "1.0/league-website/" + chosenLeagueId + "/results?month=04&team_id=" + ChosenTeamId + "&limit=31&timestamp=" + unixTimeStamp;
resultsFeedURL = "https://www.website.com/_services/api/" + 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);


           }

           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);






          Log.v("lc", "resultsDict" + resultsDict);





    } 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 loadnews(){

         newsFeedRequest = "1.0/league-website/" + chosenLeagueId + "/news?timestamp=" + unixTimeStamp;
         newsFeedURL = "https://www.website.com/_services/api/" + newsFeedRequest;  

    String myhash = buildHmacSignature(apiKey, newsFeedURL);



    Log.v("lc" , "resultsurl=" + resultsFeedURL);
    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 mergeAdapterSetup(){    


    arrayAdapter = new ArrayAdapter<String>(this, R.layout.single_item, newsList);
    arrayAdapter2 = new ArrayAdapter<String>(this, R.layout.resultscell, 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 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);
}

public void loadDataLeague(){

    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();
    }


    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);

    }   

    public void loadData(){
        loadresults();

        loadnews();
        mergeAdapterSetup();
    }

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

        PostTask jsontask;
        jsontask = new PostTask();
        jsontask.execute();





        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);


            }
        });

    }

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    if (item.getItemId() == R.id.home) {

        startActivity(new Intent(HomeActivity.this, HomeActivity.class));

        return(true);
  }


    if (item.getItemId() == R.id.match) {

        startActivity(new Intent(HomeActivity.this, MatchActivity.class));

        return(true);
  }



    if (item.getItemId() == R.id.teams) {

        startActivity(new Intent(HomeActivity.this, TeamsActivity.class));

        return(true);
  }



    if (item.getItemId() == R.id.twitter) {

        startActivity(new Intent(HomeActivity.this, TwitterActivity.class));

        return(true);
  }

    if (item.getItemId() == R.id.info) {

        startActivity(new Intent(HomeActivity.this, InfoActivity.class));

        return(true);
  }


    return(super.onOptionsItemSelected(item));


}


}

error

java.lang.NullPointerException
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1821)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1842)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.app.ActivityThread.access$1500(ActivityThread.java:132)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1038)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.os.Handler.dispatchMessage(Handler.java:99)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.os.Looper.loop(Looper.java:143)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.app.ActivityThread.main(ActivityThread.java:4263)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at java.lang.reflect.Method.invokeNative(Native Method)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at java.lang.reflect.Method.invoke(Method.java:507)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at dalvik.system.NativeStart.main(Native Method)
    06-07 12:56:34.338: E/AndroidRuntime(2688): Caused by: java.lang.NullPointerException
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at HomeActivity.onCreate(HomeActivity.java:637)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1072)
    06-07 12:56:34.338: E/AndroidRuntime(2688):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1785)

Upvotes: 1

Views: 382

Answers (1)

FabianCook
FabianCook

Reputation: 20557

Hers an example of an Async task, You should really put it in an async task because in android 3.0 > There are some rules about it not...

You need to put this in an Async task, it will not run in the main thread in 3.0 >

use this:

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

        @Override
        protected Boolean doInBackground(Void... params) {
            boolean result = false;

            //All your code goes in here 

            //If you want to do something on the UI use progress update

            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] + " ");
                }

        }
    }

You need a reference to it outside the async task

JsonTask jsontask;

then you need to start it

jsontask = new JsonTask();
jsontask.execute();

I had the exact same problem a while ago, goodluck

Upvotes: 1

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