/*
* (C) 2006 - Geotechnical Software Services
*
* This code is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This code is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
package no.geosoft.cc.util;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
/**
* A time-less and immutable Date class for basic date arithmetics.
*
* @author <a href="mailto:info@geosoft.no">GeoSoft</a>
*/
public final class Day
implements Comparable<Day>
{
/** The back end calendar instance of this day. */
private final Calendar calendar_ = Calendar.getInstance();
/**
* Create a new day. The day is lenient meaning that illegal day
* parameters can be specified and results in a recomputed day with
* legal month/day values.
*
* @param year Year of new day.
* @param month Month of new day (0-11)
* @param dayOfMonth Day of month of new day (1-31)
*/
public Day(int year, int month, int dayOfMonth)
{
initialize(year, month, dayOfMonth);
}
/**
* Create a new day, specifying the year and the day of year.
* The day is lenient meaning that illegal day parameters can be
* specified and results in a recomputed day with legal month/day
* values.
*
* @param year Year of new day.
* @param dayOfYear 1=January 1, etc.
*/
public Day(int year, int dayOfYear)
{
initialize(year, Calendar.JANUARY, 1);
calendar_.set(Calendar.DAY_OF_YEAR, dayOfYear);
}
/**
* Create a new day representing the day of creation
* (according to the setting of the current machine).
*/
public Day()
{
// Now (in the currenct locale of the client machine)
Calendar calendar = Calendar.getInstance();
// Prune time part
initialize(calendar.get(Calendar.YEAR),
calendar.get(Calendar.MONTH),
calendar.get(Calendar.DAY_OF_MONTH));
}
/**
* Create a new day based on a java.util.Calendar instance.
* NOTE: The time component from calendar will be pruned.
*
* @param calendar Calendar instance to copy.
* @throws IllegalArgumentException If calendar is null.
*/
public Day(Calendar calendar)
{
if (calendar == null)
throw new IllegalArgumentException("calendar cannot be null");
initialize(calendar.get(Calendar.YEAR),
calendar.get(Calendar.MONTH),
calendar.get(Calendar.DAY_OF_MONTH));
}
/**
* Create a new day based on a java.util.Date instance.
* NOTE: The time component from date will be pruned.
*
* @param date Date instance to copy.
* @throws IllegalArgumentException If date is null.
*/
public Day(Date date)
{
if (date == null)
throw new IllegalArgumentException("dat cannot be null");
// Create a calendar based on given date
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
// Extract date values and use these only
initialize(calendar.get(Calendar.YEAR),
calendar.get(Calendar.MONTH),
calendar.get(Calendar.DAY_OF_MONTH));
}
/**
* Create a new day based on a time value.
* Time is milliseconds since "the Epoch" (1.1.1970).
* NOTE: The time component from time will be pruned.
*
* @param time Milliseconds since "the Epoch".
*/
public Day(long time)
{
this(new Date(time));
}
/**
* Create a new day as a copy of the specified day.
*
* @param day Day to clone.
* @throws IllegalArgumentException If day is null.
*/
public Day(Day day)
{
if (day == null)
throw new IllegalArgumentException("day cannot be null");
initialize(day.getYear(), day.getMonth(), day.getDayOfMonth());
}
/**
* Initialize the internal calendar instance.
*
* @param year Year of new day.
* @param month Month of new day.
* @param dayOfMonth Day of month of new day.
*/
private void initialize(int year, int month, int dayOfMonth)
{
calendar_.setLenient(true);
calendar_.setFirstDayOfWeek(Calendar.MONDAY);
calendar_.setTimeZone(TimeZone.getTimeZone("GMT"));
calendar_.set(Calendar.YEAR, year);
calendar_.set(Calendar.MONTH, month);
calendar_.set(Calendar.DAY_OF_MONTH, dayOfMonth);
// Prune the time component
calendar_.set(Calendar.HOUR_OF_DAY, 0);
calendar_.set(Calendar.MINUTE, 0);
calendar_.set(Calendar.SECOND, 0);
calendar_.set(Calendar.MILLISECOND, 0);
}
/**
* A more explicit front-end to the Day() constructor which return a day
* object representing the day of creation.
*
* @return A day instance representing today.
*/
public static Day today()
{
return new Day();
}
/**
* Return a Calendar instance representing the same day
* as this instance. For use by secondary methods requiring
* java.util.Calendar as input.
*
* @return Calendar equivalent representing this day.
*/
public Calendar getCalendar()
{
return (Calendar) calendar_.clone();
}
/**
* Return a Date instance representing the same date
* as this instance. For use by secondary methods requiring
* java.util.Date as input.
*
* @return Date equivalent representing this day.
*/
public Date getDate()
{
return getCalendar().getTime();
}
/**
* Compare this day to the specified day. If object is
* not of type Day a ClassCastException is thrown.
*
* @param day Day object to compare to.
* @return @see Comparable#compareTo(Object)
* @throws IllegalArgumentException If day is null.
*/
public int compareTo(Day day)
{
if (day == null)
throw new IllegalArgumentException("day cannot be null");
return calendar_.getTime().compareTo(day.calendar_.getTime());
}
/**
* Return true if this day is after the specified day.
*
* @param day Day to compare to.
* @return True if this is after day, false otherwise.
* @throws IllegalArgumentException If day is null.
*/
public boolean isAfter(Day day)
{
if (day == null)
throw new IllegalArgumentException("day cannot be null");
return calendar_.after(day.calendar_);
}
/**
* Return true if this day is before the specified day.
*
* @param day Day to compare to.
* @return True if this is before day, false otherwise.
* @throws IllegalArgumentException If day is null.
*/
public boolean isBefore(Day day)
{
if (day == null)
throw new IllegalArgumentException("day cannot be null");
return calendar_.before(day.calendar_);
}
/**
* Return true if this day equals (represent the same date)
* as the specified day.
*
* @param object Object to compare to.
* @return True if this equals day, false otherwise.
* @throws IllegalArgumentException If day is null.
*/
@Override
public boolean equals(Object object)
{
Day day = (Day) object;
if (day == null)
throw new IllegalArgumentException("day cannot be null");
return calendar_.equals(day.calendar_);
}
/**
* Overload required as default definition of equals() has changed.
*
* @return A hash code value for this object.
*/
@Override
public int hashCode()
{
return calendar_.hashCode();
}
/**
* Return year of this day.
*
* @return Year of this day.
*/
public int getYear()
{
return calendar_.get(Calendar.YEAR);
}
/**
* Return month of this day. The result must be compared to Calendar.JANUARY,
* Calendar.FEBRUARY, etc.
*
* @return Month of this day.
*/
public int getMonth()
{
return calendar_.get(Calendar.MONTH);
}
/**
* Return the 1-based month number of the month of this day.
* 1 = January, 2 = February and so on.
*
* @return Month number of this month
*/
public int getMonthNo()
{
// It is tempting to return getMonth() + 1 but this is conceptually
// wrong, as Calendar month is an enumeration and the values are tags
// only and can be anything.
switch (getMonth()) {
case Calendar.JANUARY : return 1;
case Calendar.FEBRUARY : return 2;
case Calendar.MARCH : return 3;
case Calendar.APRIL : return 4;
case Calendar.MAY : return 5;
case Calendar.JUNE : return 6;
case Calendar.JULY : return 7;
case Calendar.AUGUST : return 8;
case Calendar.SEPTEMBER : return 9;
case Calendar.OCTOBER : return 10;
case Calendar.NOVEMBER : return 11;
case Calendar.DECEMBER : return 12;
default :
assert false : "Invalid mongth: " + getMonth();
}
// This will never happen
return 0;
}
/**
* Return day of month of this day.
* NOTE: First day of month is 1 (not 0).
*
* @return Day of month of this day.
*/
public int getDayOfMonth()
{
return calendar_.get(Calendar.DAY_OF_MONTH);
}
/**
* Return the day number of year this day represents.
* January 1 = 1 and so on.
*
* @return day number of year.
*/
public int getDayOfYear()
{
return calendar_.get(Calendar.DAY_OF_YEAR);
}
/**
* Return the day of week of this day.
* NOTE: Must be compared to Calendar.MONDAY, TUSEDAY etc.
*
* @return Day of week of this day.
*/
public int getDayOfWeek()
{
return calendar_.get(Calendar.DAY_OF_WEEK);
}
/**
* Return the day number of week of this day, where
* Monday=1, Tuesday=2, ... Sunday=7.
*
* @return Day number of week of this day.
*/
public int getDayNumberOfWeek()
{
return getDayOfWeek() == Calendar.SUNDAY ?
7 : getDayOfWeek() - Calendar.SUNDAY;
}
/**
* Return the week number of year, this day
* belongs to. 1st=1 and so on.
*
* @return Week number of year of this day.
*/
public int getWeekOfYear()
{
return calendar_.get(Calendar.WEEK_OF_YEAR);
}
/**
* Return a day which is the given number of days after this day.
*
* @param nDays Number of days to add. May be negative.
* @return Day as requested.
*/
public Day addDays(int nDays)
{
// Create a clone
Calendar calendar = (Calendar) calendar_.clone();
// Add/remove the specified number of days
calendar.add(Calendar.DAY_OF_MONTH, nDays);
// Return new instance
return new Day(calendar);
}
/**
* Subtract a number of days from this day.
*
* @param nDays Number of days to subtract.
* @return Day as requested.
*/
public Day subtractDays(int nDays)
{
return addDays(-nDays);
}
/**
* Return a day wich is a given number of month after this day.
*
* The actual number of days added depends on the staring day.
* Subtracting a number of months can be done
* by a negative argument to addMonths() or calling subtactMonths()
* explicitly.
* NOTE: addMonth(n) m times will in general give a different result
* than addMonth(m*n). Add 1 month to January 31, 2005 will give
* February 28, 2005.
*
* @param nMonths Number of months to add.
* @return Day as requested.
*/
public Day addMonths(int nMonths)
{
// Create a clone
Calendar calendar = (Calendar) calendar_.clone();
// Add/remove the specified number of days
calendar.add(Calendar.MONTH, nMonths);
// Return new instance
return new Day(calendar);
}
/**
* Subtract a number of months from this day.
* @see #addMonths(int).
*
* @param nMonths Number of months to subtract.
* @return Day as requested.
*/
public Day subtractMonths(int nMonths)
{
return addMonths(-nMonths);
}
/**
* Return a day wich is a given number of years after this day.
*
* Add a number of years to this day. The actual
* number of days added depends on the starting day.
* Subtracting a number of years can be done by a negative argument to
* addYears() or calling subtractYears explicitly.
*
* @param nYears Number of years to add.
* @return Day as requested.
*/
public Day addYears(int nYears)
{
// Create a clone
Calendar calendar = (Calendar) calendar_.clone();
// Add/remove the specified number of days
calendar.add(Calendar.YEAR, nYears);
// Return new instance
return new Day(calendar);
}
/**
* Subtract a number of years from this day.
* @see #addYears(int).
*
* @param nYears Number of years to subtract.
* @return Day as requested.
*/
public Day subtractYears(int nYears)
{
return addYears(-nYears);
}
/**
* Return the number of days in the year of this day.
*
* @return Number of days in this year.
*/
public int getDaysInYear()
{
return calendar_.getActualMaximum(Calendar.DAY_OF_YEAR);
}
/**
* Return true if the year of this day is a leap year.
*
* @return True if this year is a leap year, false otherwise.
*/
public boolean isLeapYear()
{
return getDaysInYear() == calendar_.getMaximum(Calendar.DAY_OF_YEAR);
}
/**
* Return true if the specified year is a leap year.
*
* @param year Year to check.
* @return True if specified year is leap year, false otherwise.
*/
public static boolean isLeapYear(int year)
{
return (new Day(year, Calendar.JANUARY, 1)).isLeapYear();
}
/**
* Return the number of days in the month of this day.
*
* @return Number of days in this month.
*/
public int getDaysInMonth()
{
return calendar_.getActualMaximum(Calendar.DAY_OF_MONTH);
}
/**
* Get default locale name of this day ("Monday", "Tuesday", etc.
*
* @return Name of day.
*/
public String getDayName()
{
switch (getDayOfWeek()) {
case Calendar.MONDAY : return "Monday";
case Calendar.TUESDAY : return "Tuesday";
case Calendar.WEDNESDAY : return "Wednesday";
case Calendar.THURSDAY : return "Thursday";
case Calendar.FRIDAY : return "Friday";
case Calendar.SATURDAY : return "Saturday";
case Calendar.SUNDAY : return "Sunday";
default :
assert false : "Invalid day of week: " + getDayOfWeek();
}
// This will never happen
return null;
}
/**
* Return number of days between two days.
* The method always returns a positive number of days.
*
* @param day The day to compare to.
* @return Number of days between this and day.
* @throws IllegalArgumentException If day is null.
*/
public int daysBetween(Day day)
{
if (day == null)
throw new IllegalArgumentException("day cannot be null");
long millisBetween = Math.abs(calendar_.getTime().getTime() -
day.calendar_.getTime().getTime());
return (int) Math.round(millisBetween / (1000 * 60 * 60 * 24));
}
/**
* Find the n'th xxxxday of s specified month (for instance find 1st sunday
* of May 2006; findNthOfMonth (1, Calendar.SUNDAY, Calendar.MAY, 2006);
* Return null if the specified day doesn't exists.
*
* @param n Nth day to look for.
* @param dayOfWeek Day to look for (Calendar.XXXDAY).
* @param month Month to check (Calendar.XXX).
* @param year Year to check.
* @return Required Day (or null if non-existent)
* @throws IllegalArgumentException if dyaOfWeek parameter
* doesn't represent a valid day.
*/
public static Day getNthOfMonth(int n, int dayOfWeek, int month, int year)
{
// Validate the dayOfWeek argument
if (dayOfWeek < 0 || dayOfWeek > 6)
throw new IllegalArgumentException("Invalid day of week: " + dayOfWeek);
Day first = new Day(year, month, 1);
int offset = dayOfWeek - first.getDayOfWeek();
if (offset < 0) offset = 7 + offset;
int dayNo = (n - 1) * 7 + offset + 1;
return dayNo > first.getDaysInMonth() ? null : new Day(year, month, dayNo);
}
/**
* Find the first of a specific day in a given month. For instance
* first Tuesday of May:
* getFirstOfMonth(Calendar.TUESDAY, Calendar.MAY, 2005);
*
* @param dayOfWeek Weekday to get.
* @param month Month of day to get.
* @param year Year of day to get.
* @return The requested day.
*/
public static Day getFirstOfMonth(int dayOfWeek, int month, int year)
{
return Day.getNthOfMonth(1, dayOfWeek, month, year);
}
/**
* Find the last of a specific day in a given month. For instance
* last Tuesday of May:
* getLastOfMonth (Calendar.TUESDAY, Calendar.MAY, 2005);
*
* @param dayOfWeek Weekday to get.
* @param month Month of day to get.
* @param year Year of day to get.
* @return The requested day.
*/
public static Day getLastOfMonth(int dayOfWeek, int month, int year)
{
Day day = Day.getNthOfMonth(5, dayOfWeek, month, year);
return day != null ? day : Day.getNthOfMonth(4, dayOfWeek, month, year);
}
/**
* Return a scratch string representation of this day.
* Used for debugging only. The format of the
* day is dd/mm-yyyy
*
* @return A string representation of this day.
*/
@Override
public String toString()
{
StringBuffer s = new StringBuffer();
if (getDayOfMonth() < 10)
s.append('0');
s.append(getDayOfMonth());
s.append('/');
if (getMonth() < 9)
s.append('0');
s.append(getMonth() + 1);
s.append('-');
s.append(getYear());
s.append(" ");
s.append(getDayName());
return s.toString();
}
/**
* Testing this class.
*
* @param arguments Not used.
*/
public static void main(String[] arguments)
{
// This proves that there are 912 days between the two major
// terrorist attacks, not 911 as is common knowledge.
Day september11 = new Day(2001, Calendar.SEPTEMBER, 11);
Day march11 = new Day(2004, Calendar.MARCH, 11);
System.out.println(september11.daysBetween(march11));
// This proves that Kennedy was president for 1037 days,
// not 1000 as is the popular belief nor 1036 which is the
// bluffers reply. Nerds knows when to add one...
Day precidency = new Day(1961, Calendar.JANUARY, 20);
Day assasination = new Day(1963, Calendar.NOVEMBER, 22);
System.out.println(precidency.daysBetween(assasination) + 1);
// Niel Armstrong walked the moon on a Sunday
Day nielOnMoon = new Day(1969, Calendar.JULY, 20);
System.out.println(nielOnMoon.getDayName());
// Find last tuesdays for 2005
for (int i = 0; i < 12; i++) {
Day tuesday = Day.getLastOfMonth(Calendar.TUESDAY, i, 2005);
System.out.println(tuesday);
}
}
}