자답입니다 ㅎㅎ
혼자 너무 어렵게 생각했네요
int month = datePicker.getMonth()+1;
int day = datePicker.getDayOfMonth();
int hour = timePicker.getCurrentHour();
int minute = timePicker.getCurrentMinute();
Calendar calender = Calendar.getInstance();
calender.set(year, month,day, hour,minute);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
String strDate = sdf.format(calender.getTime());