//HH converts hour in 24 hours format (0-23), day calculation
    SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");

    Date d1 = null;
    Date d2 = null;


        d1 = format.parse(dateStart);
        d2 = format.parse(dateStop);

        //in milliseconds
        long diff = d2.getTime() - d1.getTime();

                    long diffSeconds = diff / 1000 % 60;
        long diffMinutes = diff / (60 * 1000) % 60;
        long diffHours = diff / (60 * 60 * 1000) % 24;
        long diffDays = diff / (24 * 60 * 60 * 1000);

                    String ago="";

                    if(diffDays!=0){
                        ago=diffDays+" days ago";
                    }
                    else if(diffHours!=0){
                        ago=diffHours+" hours ago";
                    }
                    else if(diffMinutes!=0){
                        ago=diffMinutes+" minutes ago";
                    }
                    else if(diffSeconds!=0){
                        ago=diffSeconds+" seconds ago";
                    }