I have an activity, which contains 2 fragments, each fragment has 2 list views, each has an adapter. So I get pretty long data in json from the server, I use AsyncTask and on post execute, I parse the data. The problem is that it freezes the loading animation for 4-5 seconds.
I have tried to use Handler thread, but the problem is still there, I must be doing something terribly wrong here.
public class DataService extends AsyncTask<String, String, Void> { @Override protected Void doInBackground(String... params) { url = new URL(DATA_URL); //Connection stuff String jsonString = stringBuilder.toString(); jsonObject = new JSONObject(jsonString); //Adding data in Java Objects } @Override protected void onPostExecute(Void aVoid) { super.onPostExecute(aVoid); //Upcoming List in Fragment allDataFragment.setUpcomingDataList(UpcomingAllDataList); awayFragment.setUpcomingDataList(tUpcomingAwayList); homeFragment.setUpcomingDataList(tUpcomingHomeList); //Past List in Fragment allDataFragment.setPastDataList(pastAllDataList); awayFragment.setPastDataList(pastAwayList); homeFragment.setPastDataList(pastHomeList); } I added log messages in adapter, and I can see that at the time of parsing rows it freezes, so it take all the post execute stuff in handler thread
Handler handler= new Handler(); handler.post(new Runnable() { @Override public void run() { //Upcoming List in Fragment allDataFragment.setUpcomingDataList(UpcomingAllDataList); awayFragment.setUpcomingDataList(tUpcomingAwayList); homeFragment.setUpcomingDataList(tUpcomingHomeList); //Past List in Fragment allDataFragment.setPastDataList(pastAllDataList); awayFragment.setPastDataList(pastAwayList); homeFragment.setPastDataList(pastHomeList); } }); I also tried to add a handler in Adapter but it fails to load UI component from there.
This is a snippet from my fragment code.
if (pastListView != null) { PastListAdapter allGamesAdapter = new PastListAdapter(getContext(), pastAllDataList); pastListView.setAdapter(allGamesAdapter); } and in Adapter i am doing following.
@Override public View getView(int position, View convertView, ViewGroup parent) { TextView vScore = (TextView) v.findViewById(R.id.v_score); TextView date = (TextView) v.findViewById(R.id.date); ImageView image = (ImageView) v.findViewById(R.id.iv_image); //7 Other views vScore.setText(dataList.get(position).getScore); date.setText(dataList.get(position).date); Log.d(TAG, "getView: Row"); return v; } The loading animation works fine in start but at the time it starts parsing the data in adapter, it hangs t he UI thread.
5 Answers
Answers 1
Use AsyncTask to handle work items shorter than 5ms ( 5 milli seconds) in duration. Since you are getting pretty long JSON data from server, you have to look at other alternatives ( Thread, HandlerThread and ThreadPoolExecutor)
Even though you create Handler, it's running on UI Thread only. Instead of Handler, use HandlerThread
Proposed solution:
Use
HandlerThreadto get JSON data from server. UI Thread is not blocked to get the data.Post Data from
HandlerThreadtoHandlerof UI Thread. UI Handler will take care of updating UI with data received onhandleMessage(Message msg)
Useful posts:
Asynctask vs Thread vs Services vs Loader
Handler vs AsyncTask vs Thread
Why to use Handlers while runOnUiThread does the same? ( This post contains code example for above proposed solution)
Answers 2
If it's blocking the ui thread then don't do it in the ui thread
You already got an asyncTask so just use it and call your parsing json function from there
Then you can return void from that task and update your adopter from there
In other words, move your logic from onPostExecute to doInBackground
Answers 3
Use Volley instead of AsyncTask
Answers 4
at the beginning, i advise you, not be a lazy, and look to libraries
Retrofit - RESTfull client library
You do not need to write AsyncTasks with these libraries, and this will make your life easier and painless.
But, if you won't, ok. Let's talk about AsyncTask problems and decisions of your concerns.
AsyncTask are runs on a background computation thread and whose result is published on the UI thread. They are defined by 3 generic types, called Params, Progress and Result, and 4 steps, called begin, doInBackground, progress updating and end of computations with updating UI. So, when it is executed, the task goes through 4 steps:
1 step. onPreExecute(), invoked on the UI thread immediately after the task is executed. This step is basically used to configure the task, for example showing a progress bar, progress dialog or any other changes in the UI.
2 step. doInBackground(Params...), invoked on the background thread immediately after onPreExecute() finishes executing. This step is used to perform background computation that can take a long time. The parameters of the asynchronous task are passed to this step. The result of the computation must be returned by this step and will be passed back to the last step. This step can also use publishProgress(Progress...) to publish one or more units of progress. These values are published on the UI thread, in the onProgressUpdate(Progress...) step.
3 step. onProgressUpdate(Progress...), invoked on the UI thread after a call to publishProgress(Progress...). The timing of the execution is undefined. This method is used to display any form of progress in the user interface while the background computation is still executing. For instance, it can be used to animate a progress bar or show logs in a text field.
4 step. onPostExecute(Result), invoked on the UI thread after the background computation finishes. The result of the background computation is passed to this step as a parameter.
So, as you also now, if you don't want catch performance freezing, you have to return result of the computation in 2 step.
public class DataService extends AsyncTask<String, String, List<UpcomingAllDataList>> { @Override protected List<UpcomingAllDataList> doInBackground(String... params) { // making HTTP request return UpcomingAllDataList; // return results of Http request } @Override protected void onPostExecute(List<UpcomingAllDataList> upcomingAllDataList) { super.onPostExecute(upcomingAllDataList); //Upcoming List in Fragment allDataFragment.setUpcomingDataList(upcomingAllDataList); // all another work } } Hope, it will be usefull.
Answers 5
you should really use Retrofit for the server call + parsing.
Retrofit Github
I think the real problem is that you parse more data in setUpcomingDataList (and all the others) methods.
anyway, your example for HandlerThread is actually happening in the UI thread since Handler's default constructor takes the current thread that you construct the Handler on (which in your case is the UI thread) and post the Runnable to that thread.
anyway 2 - to see if it the methods would really work in a different thread (i guess you will get an android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. )
you can try to wrap your code with normal thread:
Thread thread = new Thread(new Runnable() { @Override public void run() { //Upcoming List in Fragment allDataFragment.setUpcomingDataList(UpcomingAllDataList); awayFragment.setUpcomingDataList(tUpcomingAwayList); homeFragment.setUpcomingDataList(tUpcomingHomeList); //Past List in Fragment allDataFragment.setPastDataList(pastAllDataList); awayFragment.setPastDataList(pastAwayList); homeFragment.setPastDataList(pastHomeList); } }); thread.start(); which is a really bad practice - so as I said before, use Retrofit.
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