Question

I am writing Android apps using Eclipse + SDK 8, running at Android 2.2 emulator.

I create an AsyncTask to process lengthy task in background. Below is the code:

    public class taskSavingFavourite extends AsyncTask<Void, Void, Integer> 
{       
    @Override
    protected Integer doInBackground(Void... arg0) 
    {
        List<MainListClass> mList = new ArrayList<MainListClass>();
        String s = null;
        int addedCount= 0;

        if (mainListSubTabSelectedTab == 0) mList = buildingList;
        else mList = storeList;
        if (mList == null) return 0;
        try
        {
            for (int i = 0; i < mList.size(); i ++)
            {
                if (mList.get(i).checked == 1) 
                {
                    s = htFavourite.get(mList.get(i).id+"-"+mList.get(i).type);
                    if (s == null) 
                    {
                        addedCount ++;
                        if (!favouriteList.equals(""))
                            favouriteList = favouriteList + ";";
                        favouriteList = favouriteList +
                                        mList.get(i).id + "-" + mList.get(i).type + ":" +
                                        mList.get(i).name;
                        htFavourite.put(mList.get(i).id + "-" + mList.get(i).type, 
                                        mList.get(i).name);
                        mList.get(i).favourite = 1;
                    }
                }
                publishProgress();
            }
            if (addedCount != 0)
            {
                SharedPreferences settings = getSharedPreferences("MGS_PRIVATE_DATA", 0);
                SharedPreferences.Editor editor = settings.edit();
                editor.putString("favouriteList", favouriteList);
                //Commit the edits!
                editor.commit();
            }
        }
        catch (Exception e) {};
        return addedCount;
    }
}

The problem is: When the mList is large (1000+ items), current Activity will be force closed and back to launcher Activity. I quite confirm it is not crashed because the annoying “Unfortunately the …” dialog is not coming out.

I check the logcat and when it happens, it always have this message:

12-10 14:10:28.772: D/dalvikvm(976): threadid=9: sending two SIGSTKFLTs to threadid=2 (tid=977) to cause debuggerd dump 
12-10 14:10:30.842: D/dalvikvm(976): Sent, pausing to let debuggerd run 
12-10 14:10:38.903: D/dalvikvm(976): Continuing 12-10 14:10:38.903: E/dalvikvm(976): **VM aborting***

I am not sure whether this is android bug or I am missing out something.

Answer 1

Alright, I think I found the reason: Never use tight loop inside AsyncTask:DoinBackground.

So I just put Thread.Sleep(1) inside the loop then everything works like a charm. Maybe this will just happen in emulator, not a real device (I just guess).