postAtTime not triggering

Question

I'm trying to make an application that changes the UI every minute, but I'm struggling a lot with the postAtTime function because I can't make it trigger. I've tried it with postDelay and it works, but postAtTime should give me more precission.

I get the current time and set a calendar, then add a minute to the date and call the postAtTime, but it does not trigger. Let's see if you could help me.

   private Runnable showMinute = new Runnable() {
    public void run() {
        calendar = Calendar.getInstance();
        minute = calendar.get(Calendar.MINUTE);
        minute = minute % 10;

        switch (minute){
        case 0: numero.setImageResource(R.drawable.b0);
            break;
        case 1: numero.setImageResource(R.drawable.b1);
            break;
        case 2: numero.setImageResource(R.drawable.b2);
            break;
        case 3: numero.setImageResource(R.drawable.b3);
            break;
        case 4: numero.setImageResource(R.drawable.b4);
            break;
        case 5: numero.setImageResource(R.drawable.b5);
            break;
        case 6: numero.setImageResource(R.drawable.b6);
            break;
        case 7: numero.setImageResource(R.drawable.b7);
            break;
        case 8: numero.setImageResource(R.drawable.b8);
            break;
        case 9: numero.setImageResource(R.drawable.b9);
            break;
        default:
            break;
        }


        handler.removeCallbacks(mostrarHora);
        calendar.add(Calendar.MINUTE, 1);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        handler.postAtTime(showMinute, calendar.getTimeInMillis());
    }
  };

Answer 1

You are using the absolute time (from the Calendar class). The handler.postAtTime timeformat is the amount of ms since startup.

You should use SystemClock.uptimeMillis() for your calculation.