multithreading UI : exceptionininitializererror and runtime exception android

Question

I'm trying to make multithreading but I've got this stacktrace on few smartphones (SGS2) :

java.lang.ExceptionInInitializerError
at com.android.bordeaux.code.model.AnnouncersContainer.setLoudArrayFromJSON_online(AnnouncersContainer.java:68)
at com.android.bordeaux.code.SplashscreenActivity_Second$1.run(SplashscreenActivity_Second.java:55)
Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
at android.os.Handler.<init>(Handler.java:121)
at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
at android.os.AsyncTask$InternalHandler.<init>(AsyncTask.java:421)
at android.os.AsyncTask.<clinit>(AsyncTask.java:152)
... 2 more

Here is my main activity (splashscreen) wich is making wait during few seconds in order to wait my asynctask finish:

    public class SplashscreenActivity_Second extends Activity 
        {       
            @Override
            public void onCreate(Bundle savedInstanceState) 
            {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.splashscreen_second);

                // thread
                Thread splashThread = new Thread()
                {
                    @Override
                    public void run()
                    {
                        try
                        {
                            int waited = 0;

                            if (isInternetOn())
                            {
// Here I'm making my asynctask !!
AnnouncersContainer.setLoudArrayFromJSON_online(getApplicationContext());
                                while (waited < 5000)
                                {
                                    sleep(50);
                                    waited += 40;
                                }
                            }
                            else
                            {                       
                                AnnouncersContainer.setLoudArrayFromXML_local(getApplicationContext());
                                while(waited < 5000)
                                {
                                    sleep(50);
                                    waited += 60;
                                }
                            }
                        }
                        catch( InterruptedException e )
                        {
                            e.printStackTrace();
                        }
                        finally
                        {
                            Intent intent_to_tabhost = new Intent(SplashscreenActivity_Second.this, MyTabActivity.class);
                            startActivity(intent_to_tabhost);
                            finish();
                        }
                    }
                };
                splashThread.start();
            }
}

Here is my asynctask :

public class DownloadAnnouncers extends AsyncTask<Void, Integer, Boolean>
{
    public static Boolean loadFinished = false;

    //JSON variables..


    private static String url = null;

    Context context;

    public DownloadAnnouncers(Context context) 
    {
        this.context = context;
    }

    @Override
    protected void onPreExecute() 
    {
        super.onPreExecute();
    }

    protected Boolean doInBackground(Void... params) 
    {

    // fine retrieving all my JSON data in a global array..

    }

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

I know the problem is that I'm making multithreading in the UI but someone can tell me how to delete my looping thread and replacing it just with onPostExecute() method of my Asynctask ?? (it could be better to wait for asynctask finishes rather than making wait..)

Or may be help me to correct this bug with multithreading..

EDIT :

my asynctask :

public class DownloadAnnouncers extends AsyncTask<Void, Integer, Boolean>
    {
        public static Boolean loadFinished = false;

        //JSON variables..


        private static String url = null;

        Context context;

        public DownloadAnnouncers(Context context) 
        {
            this.context = context;
        }

        @Override
        protected void onPreExecute() 
        {
            super.onPreExecute();
        }

        protected Boolean doInBackground(Void... params) 
        {

        // fine retrieving all my JSON data in a global array..

        }

        @Override
        protected void onPostExecute(Boolean downloadedArray) 
        {
            super.onPostExecute(downloadedArray);
        Intent intent_to_tabhost = new Intent(context, MyTabActivity.class);
        intent_to_tabhost.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent_to_tabhost);
        }
    }

But now if I press cancel button I'm returning to my splashscreen activity.. and I cannot do ctx.finish() in onPostExecute method..

score 1 · Accepted Answer · answered Feb 10 '13 at 13:50

You can't create a Handler inside a Thread that has not called Looper.prepare(), just as your Error message says:

Can't create handler inside thread that has not called Looper.prepare()

The Handler is created within the AsyncTask, so it's not something you might see at first.

If you want to keep your code as it is you would fix it by moving the creation of the AsyncTask to outside your custom Thread.

However, there is no need for you to create the thread, you can just create your AsyncTask in the ui thread (It will run on it's own thread so it won't lock your phone while working), and perform any action you want after the task is complete in the onPostExecute-method.

class ExampleAsync extends AsyncTask<Void, Integer, Boolean>
{
    public static Boolean loadFinished = false;
    //JSON variables..
    private static String url = null;
    Context context;

    public DownloadAnnouncers(Context context){
        this.context = context;
    }

    protected Boolean doInBackground(Void... params){
        // fine retrieving all my JSON data in a global array..
    }

    @Override
    protected void onPostExecute(Boolean downloadedArray){
        Intent intent_to_tabhost = new Intent(context, MyTabActivity.class);
        startActivity(intent_to_tabhost);
    }
}

And in your Activity:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.splashscreen_second);
    AsyncTask myTask = new ExampleAsync(this);
    myTask.execute();
}

score 0 · Answer 2 · answered Feb 10 '13 at 13:53

0

Instead of waiting for the asyncTask , use the onPostExecute , which is called on the UI thread only after the task has finished.

You should also cancel the task if the activity was destroyed (for example if the user has pressed the back button while the splash screen is shown) .

answered Feb 10 '13 at 13:53

android developer

114,585
152
739
1,270

Finally it works, I had to add the asynctask into my splashscreen activity (the asynctask wasnt internal before) so I can call finish() – eento Feb 10 '13 at 14:40

multithreading UI : exceptionininitializererror and runtime exception android

2 Answers2