DateUtils { public static int getLastWeekOfYear(int year) { LocalDate date = createLocalDate("3112" + year); WeekFields weekFields = WeekFields.ISO; int weekNumber = date.get(weekFields.weekOfWeekBasedYear()); while (weekNumber == 1) { date = date.minusDays(1); weekNumber = date.get(weekFields.weekOfWeekBasedYear()); } return weekNumber; } private  DateUtils(); @SuppressWarnings("unchecked") static T createJava8Date(Class<T> clazz, String dateStr, String format); static LocalDate createLocalDate(String dateStr); static LocalDate createLocalDate(String dateStr, String format); static LocalDateTime createLocalDateTime(String dateTimeStr); static LocalDateTime createLocalDateTime(String dateTimeStr, String format); static LocalTime createLocalTime(String timeStr); static LocalTime createLocalTime(String timeStr, String format); static ZonedDateTime createZonedDateTime(String dateTimeStr); static ZonedDateTime createZonedDateTime(String dateTimeStr, String format); static String formatDate(LocalDate date, String format); static String formatDateTime(LocalDateTime dateTime, String format); static String formatJava8Date(Class<?> clazz, Object value, String format); static String formatTime(LocalTime time, String format); static String formatZonedDateTime(ZonedDateTime dateTime, String format); static int getLastWeekOfYear(int year); static String getNextWeekCode(String weekCode); static int getQuarter(LocalDate date); static LocalDate getStartDateOfWeek(String weekCode); static boolean isJava8DateType(Class<?> clazz); static boolean isSupportedDateType(Class<?> clazz); static boolean isValidWeekCode(String weekCode); static Date toLegacyDate(LocalDate d); static Date toLegacyDate(LocalDateTime ldt); static String toWeekCode(LocalDate date); static final String WEEK_CODE_PATTERN; }
@Test public void testGetLastWeekOfYear() { assertEquals(52, DateUtils.getLastWeekOfYear(2017)); assertEquals(52, DateUtils.getLastWeekOfYear(2016)); assertEquals(53, DateUtils.getLastWeekOfYear(2015)); assertEquals(53, DateUtils.getLastWeekOfYear(2009)); }