Android : After Converting GMT time date not in 24hour format android code

I was trying to converted user inputed date in GMT time, user inputed date in 24hour format, when i convert in GMT time it show 12 hour problem, How can i get 24 hour formated GMT time

SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");


    String s = starttDatePicker.getYear() + "-"
        + (starttDatePicker.getMonth() + 1) + "-"
        + starttDatePicker.getDayOfMonth() + " "
        + starttimepicer.getCurrentHour() + ":"
        + starttimepicer.getCurrentMinute() + ":" + "00";

Date parsed = null;

try {
    parsed = format1.parse(s);
} catch (ParseException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
TimeZone tz = TimeZone.getTimeZone("GMT");
format1.setTimeZone(tz);

posttime = format1.format(parsed);