Screen freezes while executing Async task

Question

Am doing a heavy server task within Asynctask. As soon as some portion of data is get downloaded i need to call an method who deals with some ui elements on main thread. But its not working for me.The screen remains free zed until it complete the Async task. So how can i make that method run on main thread and my background task should also be running?

Here is my code

public class  AsyncgetTestDetailsfromServer extends AsyncTask<Void ,Void,Integer>
{
    @Override
    protected Integer doInBackground(Void... params) {
                    Ion.with(TestActivity.this)
                      .load(AppConstants.GET_TEST_QUESTION_ANSWER+"testID="+Test_id)
                      .setTimeout(30000)
                      .asString().setCallback(new FutureCallback<String>() {
                        @Override
                        public void onCompleted(Exception e, String response) {
                            if (e != null) {
                                e.printStackTrace();
                                displayAlert(TestActivity.this,
                                        getString(R.string.app_name),
                                        getString(R.string.strInternetSlow), "0");
                            }
                            if(response!=null){
                                try {
                                    JSONArray jsonArray = new JSONArray(response);

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

                                        JSONObject jsonObject = (JSONObject) jsonArray.get(i);
                                        String result = jsonObject.getString("TransactionStatus");

                                        if(result.equals("Success"))
                                        {
                                            JSONArray  testArray = (JSONArray) jsonObject.get("TestDetails");
                                            for(int j=0;j<testArray.length();j++)
                                            {
                                                JSONObject  obj = (JSONObject) testArray.get(j);
                                                JSONArray  SubjectArray = (JSONArray) obj.get("SubjectList");
                                                QueCount=0;

                                                for(int k=0;k<SubjectArray.length();k++)
                                                {
                                                    JSONObject  SubObj = (JSONObject) SubjectArray.get(k);
                                                    JSONArray  QuestionArray = (JSONArray) SubObj.get("QuestionList");

                                                    if (QuestionArray != null && QuestionArray.length() > 0) {

                                                        for(int l=0;l<QuestionArray.length();l++)
                                                        {
                                                            QueCount++;

                                                            // Contains some database operations...

                                                            if(QueCount==51)
                                                            {
                                                                  TestActivity.this.runOnUiThread(new Runnable() {
                                                                       @Override
                                                                       public void run() {
                                                                           DisplayQuestion();
                                                                           BaseActivity.StopLoadingDialog();
                                                                           StartTimer();
                                                                       }
                                                                    });
                                                            }
                                                       }
                                                        if(QueCount<=50){
                                                           DisplayQuestion();
                                                           BaseActivity.StopLoadingDialog();
                                                           StartTimer();
                                                        }
                                                   }
                                                    else
                                                    {
                                                        displayAlert(act,
                                                                getString(R.string.app_name),
                                                                getString(R.string.strNoQuestionFound), "1");
                                                    }
                                                }
                                            }
                                        }
                                        if(result.equals("Error"))
                                        {
                                            int ErrorCode = jsonObject.getInt("ERROR");
                                            showErrorMessage(ErrorCode,TestActivity.this);
                                        }
                                    }
                                } catch (JSONException e1) {
                                    e1.printStackTrace();
                                }

                            }
                        }
                    });

        return  QueCount;
    }
}

and called at

new AsyncgetTestDetailsfromServer().execute();

Answer 1

I don't really know how your callback is working but the screen might freeze because of it. Asynctask implements a onPostExecute method that in which you can use a callback.

Callback interface :

public interface AsyncTaskCompleteListener<T> {
    public void onTaskComplete(T result, int number);
}

AsyncTask :

public class LoadURL extends AsyncTask<String, Process, String> {

    private AsyncTaskCompleteListener<String> callback;

    public LoadURL(AsyncTaskCompleteListener<String> cb) {
        this.callback = cb;
     }

    protected void onPreExecute() {}

    protected String doInBackground(String... arg0) {
         // do something
        return content;
    }

    protected void onPostExecute(String content) {
        if (callback != null)
            callback.onTaskComplete(content,number);
    }
}

Activity :

public class LoginActivity extends Activity implements AsyncTaskCompleteListener<String> {

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        LoadURL loadUrl = new LoadURL(LoginActivity.this);
        loadUrl.execute(...);
    }

    @Override
    public void onTaskComplete(String result, int number) {...}
}

I never had any freeze problem with thise code. Hope this will help

Answer 2

When you have callback function then why you doing work in background just remove asyncTask code, start from below code,

Your code will work without asyncTask as i can see because of CallBack method.

 Ion.with(TestActivity.this)
                          .load(AppConstants.GET_TEST_QUESTION_ANSWER+"testID="+Test_id)
                          .setTimeout(30000)
                          .asString().setCallback(new FutureCallback<String>() {
                            @Override
                            public void onCompleted(Exception e, String response) {
                                if (e != null) {
                                    e.printStackTrace();
                                    displayAlert(TestActivity.this,
                                            getString(R.string.app_name),
                                            getString(R.string.strInternetSlow), "0");
                                }
                                ..................
,,,,,
...................
....................

Use async inside

 if(response!=null){
    try {
      //Use asyncTask here...
     }