Toast inside thread during heavy workload task

Question

I am updating a database (SQLite) with a lot of data, which takes several minutes. I am doing this on a Thread. At the same time I want to show the progression of the updates (25%, 50%, etc.) through a Toast. Since I am within a thread, I need to use the runOnUiThread() function to run the Toast. Like this:

getActivity().runOnUiThread(new Runnable() {
                    public void run() {
                        Toast.makeText(getActivity(),"Updating the database...", Toast.LENGTH_SHORT).show();
                    }
                });

It was working fine when the workload was not to big. Now that it is, no toast is being displayed at all.

I have been looking for ways to set a very high priority to the toast's thread, without success. Maybe I can bypass using a thread for the toast in the first place?

Thank you for the insights!

EDIT: In fact, the toast is working, but is displayed after all the work has been done. I want to notify the percentage of the complete update to the user, so I need to have the toast displayed during the update and not after.

I tried removing the workload (no database update, only a Log.d inside the for loop of things to add to the database). And the toast are displayed after the loop is finished although the runOnUiThread() method is called inside the loop.

EDIT 2: I managed to do what I wanted after cleaning up the code and starting fresh. I posted the code I used as the answer below.

Answer 1

After having cleaned up the initial thread, I managed to have something working. I post the code here since it can be used as a template to do a specific task:

Run a initial thread that does tasks periodically for a given number of times (here collect some data). After this given number of times, the collected data is pushed to a database and the user is notified of the advancement of the process (which takes a long time).

Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask(){
    long t0 = System.currentTimeMillis();
    @Override
    public void run() {
        if(System.currentTimeMillis() - t0 > EXPERIMENT_DURATION ){
            processData(dataArrayList); // custom tasks - see below
            cancel();
        }else {
            dataArrayList = collectData(); // custom tasks
        }
    }
}, 0, INTERVAL);

With:

void processData(Arraylist<Data> dataArrayList){
    for(Data data : dataArrayList){
        // show progression to the user
        getActivity().runOnUiThread(new Runnable() {
            @Override
            public void run() {
                int percent = Math.round(((float)dataArrayList.indexOf(data))/((float)dataArrayList.size())*100)
                Toast.makeText(getActivity(),"Update: " + Integer.toString(percent) + "%", Toast.LENGTH_LONG).show();
            }
        });

        updateDataBase(data);
    }
}