Java tutorial
import java.util.Calendar; import java.util.Date; public class DateUtils { /** * <p>Checks if two dates are on the same day ignoring time.</p> * @param date1 the first date, not altered, not null * @param date2 the second date, not altered, not null * @return true if they represent the same day * @throws IllegalArgumentException if either date is <code>null</code> */ public static boolean isSameDay(Date date1, Date date2) { if (date1 == null || date2 == null) { throw new IllegalArgumentException("The dates must not be null"); } Calendar cal1 = Calendar.getInstance(); cal1.setTime(date1); Calendar cal2 = Calendar.getInstance(); cal2.setTime(date2); return isSameDay(cal1, cal2); } /** * <p>Checks if two calendars represent the same day ignoring time.</p> * @param cal1 the first calendar, not altered, not null * @param cal2 the second calendar, not altered, not null * @return true if they represent the same day * @throws IllegalArgumentException if either calendar is <code>null</code> */ public static boolean isSameDay(Calendar cal1, Calendar cal2) { if (cal1 == null || cal2 == null) { throw new IllegalArgumentException("The dates must not be null"); } return (cal1.get(Calendar.ERA) == cal2.get(Calendar.ERA) && cal1.get(Calendar.YEAR) == cal2.get(Calendar.YEAR) && cal1.get(Calendar.DAY_OF_YEAR) == cal2.get(Calendar.DAY_OF_YEAR)); } /** * <p>Checks if a date is today.</p> * @param date the date, not altered, not null. * @return true if the date is today. * @throws IllegalArgumentException if the date is <code>null</code> */ public static boolean isToday(Date date) { return isSameDay(date, Calendar.getInstance().getTime()); } /** * <p>Checks if a calendar date is today.</p> * @param cal the calendar, not altered, not null * @return true if cal date is today * @throws IllegalArgumentException if the calendar is <code>null</code> */ public static boolean isToday(Calendar cal) { return isSameDay(cal, Calendar.getInstance()); } /** * <p>Checks if the first date is before the second date ignoring time.</p> * @param date1 the first date, not altered, not null * @param date2 the second date, not altered, not null * @return true if the first date day is before the second date day. * @throws IllegalArgumentException if the date is <code>null</code> */ public static boolean isBeforeDay(Date date1, Date date2) { if (date1 == null || date2 == null) { throw new IllegalArgumentException("The dates must not be null"); } Calendar cal1 = Calendar.getInstance(); cal1.setTime(date1); Calendar cal2 = Calendar.getInstance(); cal2.setTime(date2); return isBeforeDay(cal1, cal2); } /** * <p>Checks if the first calendar date is before the second calendar date ignoring time.</p> * @param cal1 the first calendar, not altered, not null. * @param cal2 the second calendar, not altered, not null. * @return true if cal1 date is before cal2 date ignoring time. * @throws IllegalArgumentException if either of the calendars are <code>null</code> */ public static boolean isBeforeDay(Calendar cal1, Calendar cal2) { if (cal1 == null || cal2 == null) { throw new IllegalArgumentException("The dates must not be null"); } if (cal1.get(Calendar.ERA) < cal2.get(Calendar.ERA)) return true; if (cal1.get(Calendar.ERA) > cal2.get(Calendar.ERA)) return false; if (cal1.get(Calendar.YEAR) < cal2.get(Calendar.YEAR)) return true; if (cal1.get(Calendar.YEAR) > cal2.get(Calendar.YEAR)) return false; return cal1.get(Calendar.DAY_OF_YEAR) < cal2.get(Calendar.DAY_OF_YEAR); } /** * <p>Checks if the first date is after the second date ignoring time.</p> * @param date1 the first date, not altered, not null * @param date2 the second date, not altered, not null * @return true if the first date day is after the second date day. * @throws IllegalArgumentException if the date is <code>null</code> */ public static boolean isAfterDay(Date date1, Date date2) { if (date1 == null || date2 == null) { throw new IllegalArgumentException("The dates must not be null"); } Calendar cal1 = Calendar.getInstance(); cal1.setTime(date1); Calendar cal2 = Calendar.getInstance(); cal2.setTime(date2); return isAfterDay(cal1, cal2); } /** * <p>Checks if the first calendar date is after the second calendar date ignoring time.</p> * @param cal1 the first calendar, not altered, not null. * @param cal2 the second calendar, not altered, not null. * @return true if cal1 date is after cal2 date ignoring time. * @throws IllegalArgumentException if either of the calendars are <code>null</code> */ public static boolean isAfterDay(Calendar cal1, Calendar cal2) { if (cal1 == null || cal2 == null) { throw new IllegalArgumentException("The dates must not be null"); } if (cal1.get(Calendar.ERA) < cal2.get(Calendar.ERA)) return false; if (cal1.get(Calendar.ERA) > cal2.get(Calendar.ERA)) return true; if (cal1.get(Calendar.YEAR) < cal2.get(Calendar.YEAR)) return false; if (cal1.get(Calendar.YEAR) > cal2.get(Calendar.YEAR)) return true; return cal1.get(Calendar.DAY_OF_YEAR) > cal2.get(Calendar.DAY_OF_YEAR); } /** * <p>Checks if a date is after today and within a number of days in the future.</p> * @param date the date to check, not altered, not null. * @param days the number of days. * @return true if the date day is after today and within days in the future . * @throws IllegalArgumentException if the date is <code>null</code> */ public static boolean isWithinDaysFuture(Date date, int days) { if (date == null) { throw new IllegalArgumentException("The date must not be null"); } Calendar cal = Calendar.getInstance(); cal.setTime(date); return isWithinDaysFuture(cal, days); } /** * <p>Checks if a calendar date is after today and within a number of days in the future.</p> * @param cal the calendar, not altered, not null * @param days the number of days. * @return true if the calendar date day is after today and within days in the future . * @throws IllegalArgumentException if the calendar is <code>null</code> */ public static boolean isWithinDaysFuture(Calendar cal, int days) { if (cal == null) { throw new IllegalArgumentException("The date must not be null"); } Calendar today = Calendar.getInstance(); Calendar future = Calendar.getInstance(); future.add(Calendar.DAY_OF_YEAR, days); return (isAfterDay(cal, today) && !isAfterDay(cal, future)); } /** Returns the given date with the time set to the start of the day. */ public static Date getStart(Date date) { return clearTime(date); } /** Returns the given date with the time values cleared. */ public static Date clearTime(Date date) { if (date == null) { return null; } Calendar c = Calendar.getInstance(); c.setTime(date); c.set(Calendar.HOUR_OF_DAY, 0); c.set(Calendar.MINUTE, 0); c.set(Calendar.SECOND, 0); c.set(Calendar.MILLISECOND, 0); return c.getTime(); } /** Determines whether or not a date has any time values (hour, minute, * seconds or millisecondsReturns the given date with the time values cleared. */ /** * Determines whether or not a date has any time values. * @param date The date. * @return true iff the date is not null and any of the date's hour, minute, * seconds or millisecond values are greater than zero. */ public static boolean hasTime(Date date) { if (date == null) { return false; } Calendar c = Calendar.getInstance(); c.setTime(date); if (c.get(Calendar.HOUR_OF_DAY) > 0) { return true; } if (c.get(Calendar.MINUTE) > 0) { return true; } if (c.get(Calendar.SECOND) > 0) { return true; } if (c.get(Calendar.MILLISECOND) > 0) { return true; } return false; } /** Returns the given date with time set to the end of the day */ public static Date getEnd(Date date) { if (date == null) { return null; } Calendar c = Calendar.getInstance(); c.setTime(date); c.set(Calendar.HOUR_OF_DAY, 23); c.set(Calendar.MINUTE, 59); c.set(Calendar.SECOND, 59); c.set(Calendar.MILLISECOND, 999); return c.getTime(); } /** * Returns the maximum of two dates. A null date is treated as being less * than any non-null date. */ public static Date max(Date d1, Date d2) { if (d1 == null && d2 == null) return null; if (d1 == null) return d2; if (d2 == null) return d1; return (d1.after(d2)) ? d1 : d2; } /** * Returns the minimum of two dates. A null date is treated as being greater * than any non-null date. */ public static Date min(Date d1, Date d2) { if (d1 == null && d2 == null) return null; if (d1 == null) return d2; if (d2 == null) return d1; return (d1.before(d2)) ? d1 : d2; } /** The maximum date possible. */ public static Date MAX_DATE = new Date(Long.MAX_VALUE); }