// 石器時代寫法
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DAY_OF_MONTH, 1); // 加1天
Date tomorrow = cal.getTime();
// 文明時代寫法
Date tomorrow = DateUtils.addDays(new Date(), 1);

// 基礎加減
Date now = new Date();
Date yesterday = DateUtils.addDays(now, -1); // 昨天
Date nextHour = DateUtils.addHours(now, 1);  // 一小時后
// 支持的時間單位：
// MILLISECOND, SECOND, MINUTE, HOUR, DAY, WEEK, MONTH, YEAR

// 判斷是否同一天
boolean sameDay = DateUtils.isSameDay(date1, date2);
// 忽略時間比較
int compare = DateUtils.truncatedCompareTo(date1, date2, Calendar.HOUR);

// 獲取當天零點
Date midnight = DateUtils.truncate(now, Calendar.DATE);
// 獲取當月第一天
Date firstDayOfMonth = DateUtils.truncate(now, Calendar.MONTH);

// 四舍五入到最近的小時
Date nearestHour = DateUtils.round(now, Calendar.HOUR);
// 向上取整到明天
Date ceilingDay = DateUtils.ceiling(now, Calendar.DATE);

Date birthday = new GregorianCalendar(1990, Calendar.JULY, 15).getTime();
Date nextBirthday = DateUtils.setYears(birthday, Year.now().getValue());
if(nextBirthday.before(new Date())) {
    nextBirthday = DateUtils.addYears(nextBirthday, 1);
}
long daysUntilBirthday = (nextBirthday.getTime() - new Date().getTime()) / (1000 * 60 * 60 * 24);

// 獲取本周所有日期
List<Date> weekDates = new ArrayList<>();
Date monday = DateUtils.truncate(DateUtils.addDays(new Date(), -Calendar.DAY_OF_WEEK + 2), Calendar.DATE);
for(int i=0; i<7; i++) {
    weekDates.add(DateUtils.addDays(monday, i));
}

// 配合TimeZone使用
TimeZone laTime = TimeZone.getTimeZone("America/Los_Angeles");
Date laDate = DateUtils.addHours(new Date(), 
    laTime.getOffset(new Date().getTime()) / (1000 * 60 * 60));

// Java 8+ 的替代方案（推薦）
LocalDate tomorrow = LocalDate.now().plusDays(1);
Instant truncated = Instant.now().truncatedTo(ChronoUnit.DAYS);
// 與Joda-Time對比（過渡方案）
DateTime jodaTime = new DateTime().plusDays(1);