import java.util.Calendar;
import java.util.Date;
 
public class DateUtils {
 
    /**
     *
 
Checks if two dates are on the same day ignoring time.
 
     * @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);
    }
 
    /**
     *
 
Checks if two calendars represent the same day ignoring time.
 
     * @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) &amp;&amp;
                cal1.get(Calendar.YEAR) == cal2.get(Calendar.YEAR) &amp;&amp;
                cal1.get(Calendar.DAY_OF_YEAR) == cal2.get(Calendar.DAY_OF_YEAR));
    }
 
    /**
     *
 
Checks if a date is today.
 
     * @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());
    }
 
    /**
     *
 
Checks if a calendar date is today.
 
     * @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());
    }
 
    /**
     *
 
Checks if the first date is before the second date ignoring time.
 
     * @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);
    }
 
    /**
     *
 
Checks if the first calendar date is before the second calendar date ignoring time.
 
     * @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);
    }
 
    /**
     *
 
Checks if the first date is after the second date ignoring time.
 
     * @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);
    }
 
    /**
     *
 
Checks if the first calendar date is after the second calendar date ignoring time.
 
     * @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);
    }
 
    /**
     *
 
Checks if a date is after today and within a number of days in the future.
 
     * @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);
    }
 
    /**
     *
 
Checks if a calendar date is after today and within a number of days in the future.
 
     * @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) &amp;&amp; ! 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 &amp;&amp; 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 &amp;&amp; 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);
 
}