Java – thread / handler error – the specified message queue synchronization barrier flag has not been published

I received this error –

As a relative newcomer to Java / Android, there is no doubt that I missed something, but what I am doing is this –

I have a project that uses EXIF data to display photos according to the shooting date. The purpose is to use similar models on each stage

Worker thread – > UI thread – > custom display adapter Then click a "cell" in the GridView to trigger the next activity The first activity searches all photo files, creates a "year" list, and then filters it into months, days, etc. for each follow-up activity

However, starting the second activity will directly start the above error and process the message through the basic thread / handler settings

This is the class that passes messages to threads –

public class MonthSort {
Handler handler;
int imageWidth;
List<PhotoData> photoList;
public MonthSort(Handler handler2,int width,List<PhotoData> pList) {
    photoList = new ArrayList<PhotoData>();
    photoList = pList;
    imageWidth = width;
    handler = handler2;
}

public void sortFiles()
{
    int month,photoCount;
    File fileName = new File("");
    Message msg = handler.obtainMessage();
    //Message msg = Message.obtain();
    //Bundle bundle = new Bundle();
    try {
        for (int i = 0; i < 12; i++) {
            month = i + 1;
            photoCount = 0;
            for (PhotoData pd : photoList) {
                if(month == pd.month)
                {
                    if(photoCount == 0)
                        fileName = pd.fileName;
                    photoCount++;
                }
            }
            if(photoCount != 0)
            {

                Bundle bundle = new Bundle();
                bundle.putString("filename",fileName.toString());
                bundle.putInt("month",month);
                bundle.putInt("count",photoCount);
                byte[] thumbNail = getThumbnail(fileName,imageWidth);
                bundle.putByteArray("thumbnail",thumbNail);


                msg.setData(bundle);
                handler.sendMessage(msg);

            }
        }
    } catch (Exception e) {
        // TODO Auto-generated catch block
        Log.d("Debug","handler error occurs in monthSort class");
    }
    /*Bundle bundle = new Bundle();
    bundle.putBoolean("end",true);
    msg.setData(bundle);
    handler.sendMessage(msg);*/
}

... this is the code that receives it in the UI thread

public class MonthActivity extends Activity {
List<PhotoData> photoList;
static List<MonthData> photos;
int imageWidth;
GridView photoGrid;
static ImageAdapter2 iAdapter;
int year;
Thread monthSortThread;

Handler handler2 = new Handler() {
    @Override
    public void handleMessage(Message msg) 
    {
        Bundle bundle = msg.getData();  // Get the message sent to the Handler.
        boolean ended = bundle.getBoolean("end");
        if(ended)
        {
            //Toast.makeText(getBaseContext(),"FINISHED !!!",Toast.LENGTH_LONG).show();
        } else
        {
            try {
                MonthData md = new MonthData();
                md.monthValue = bundle.getInt("month");
                md.monthString = getMonthString(md.monthValue);
                md.count = bundle.getInt("count");
                byte[] tn = bundle.getByteArray("thumbnail");
                md.thumbnail =  BitmapFactory.decodeByteArray(tn,tn.length);
                photos.add(md);
                iAdapter.notifyDataSetChanged();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                Log.d("Debug","handler error occurs in UI Handler");
            }
        }
    }
};

Please note that I don't include all the code, just what I think is relevant

The previous activity successfully manipulated the message in the same way, why not the second activity?

I know the main UI thread already has a looper setting, so you don't have to create one Is it still applicable to any follow-up activities?

Solution

This problem is solved by using the dispatcher message method of handler instead of SendMessage