import java.util.Random;
import java.sql.Time;

final Random random = new Random();
final int millisInDay = 24*60*60*1000;
Time time = new Time((long)random.nextInt(millisInDay));

final Random random = new Random();
for (int i = 0; i < 10; i++) {
    final LocalTime time = new LocalTime(random.nextLong());
    System.out.println(time);
}

01:58:24.328
10:59:20.576
07:52:40.011
11:53:54.524
13:43:57.474
21:51:25.032
11:46:35.988
16:20:20.224
09:47:10.404
22:35:43.337

java.util.Date dateFromDB = new java.util.Date(System.currentTimeMillis());

java.util.Date randomDate = RandomUtil.getRandomDate(new java.util.Date(RandomUtil.getMinimumDate()), new java.util.Date(RandomUtil.getMaximumDate()), false);
Calendar calendar=Calendar.getInstance();
calendar.setTime(randomDate);

calendarFromDB.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY));
calendarFromDB.set(Calendar.MINUTE, calendar.get(Calendar.MINUTE));
calendarFromDB.set(Calendar.SECOND, calendar.get(Calendar.SECOND));

dateFromDB = calendarFromDB.getTime();

java.util.Date randomDate = RandomUtil.getRandomDate(new java.util.Date(RandomUtil.getMinimumDate()), new java.util.Date(RandomUtil.getMaximumDate()), false);
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
System.out.println(sdf.format(randomDate));