sort by datetime

Collections.sort(a, new Comparator<ren>() {
@Override
public int compare(ren o1, ren o2) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
Date dt1 = format.parse(o1.getTime());
Date dt2 = format.parse(o2.getTime());
if (dt1.getTime() > dt2.getTime()) {
return 1;
} else if (dt1.getTime() < dt2.getTime()) {
return -1;
} else {
return 0;
}
} catch (Exception e) {
e.printStackTrace();
}
return 0;
}
});