## org.jfree.date
Class SerialDate

    java.lang.Object
      org.jfree.date.SerialDate

All Implemented Interfaces:
  java.io.Serializable, java.lang.Comparable, MonthConstants

Direct Known Subclasses:
  SpreadsheetDate

    public abstract class SerialDate

extends java.lang.Object
implements java.lang.Comparable, java.io.Serializable, MonthConstants

An abstract class that defines our requirements for manipulating dates, without tying down a particular implementation.

Requirement 1 : match at least what Excel does for dates; Requirement 2 : the date represented by the class is immutable;

Why not just use java.util.Date? We will, when it makes sense. At times, java.util.Date can be *too* precise - it represents an instant in time, accurate to 1/1000th of a second (with the date itself depending on the time-zone). Sometimes we just want to represent a particular day (e.g. 21 January 2015) without concerning ourselves about the time of day, or the time-zone, or anything else. That's what we've defined SerialDate for.

You can call getInstance() to get a concrete subclass of SerialDate, without worrying about the exact implementation.

Author:
  David Gilbert
See Also:
  Serialized Form

Field Summary
`static java.text.DateFormatSymbols` `DATE_FORMAT_SYMBOLS` Date format symbols.
`static int` `FIRST_WEEK_IN_MONTH` A useful constant for referring to the first week in a month.
`static int` `FOLLOWING` Useful constant for specifying a day of the week relative to a fixed date.
`static int` `FOURTH_WEEK_IN_MONTH` A useful constant for referring to the fourth week in a month.
`static int` `FRIDAY` Useful constant for Friday.
`static int` `INCLUDE_BOTH` Useful range constant.
`static int` `INCLUDE_FIRST` Useful range constant.
`static int` `INCLUDE_NONE` Useful range constant.
`static int` `INCLUDE_SECOND` Useful range constant.
`static int` `LAST_WEEK_IN_MONTH` A useful constant for referring to the last week in a month.
`static int` `MAXIMUM_YEAR_SUPPORTED` The highest year value supported by this date format.
`static int` `MINIMUM_YEAR_SUPPORTED` The lowest year value supported by this date format.
`static int` `MONDAY` Useful constant for Monday.
`static int` `NEAREST` Useful constant for specifying a day of the week relative to a fixed date.
`static int` `PRECEDING` Useful constant for specifying a day of the week relative to a fixed date.
`static int` `SATURDAY` Useful constant for Saturday.
`static int` `SECOND_WEEK_IN_MONTH` A useful constant for referring to the second week in a month.
`static int` `SERIAL_LOWER_BOUND` The serial number for 1 January 1900.
`static int` `SERIAL_UPPER_BOUND` The serial number for 31 December 9999.
`static int` `SUNDAY` Useful constant for Sunday.
`static int` `THIRD_WEEK_IN_MONTH` A useful constant for referring to the third week in a month.
`static int` `THURSDAY` Useful constant for Thrusday.
`static int` `TUESDAY` Useful constant for Tuesday.
`static int` `WEDNESDAY` Useful constant for Wednesday.

Fields inherited from interface org.jfree.date.MonthConstants
`APRIL, AUGUST, DECEMBER, FEBRUARY, JANUARY, JULY, JUNE, MARCH, MAY, NOVEMBER, OCTOBER, SEPTEMBER`

Constructor Summary
`protected` `SerialDate()` Default constructor.

Method Summary
`static SerialDate` `addDays(int days, SerialDate base)` Creates a new date by adding the specified number of days to the base date.
`static SerialDate` `addMonths(int months, SerialDate base)` Creates a new date by adding the specified number of months to the base date.
`static SerialDate` `addYears(int years, SerialDate base)` Creates a new date by adding the specified number of years to the base date.
`abstract int` `compare(SerialDate other)` Returns the difference (in days) between this date and the specified 'other' date.
`static SerialDate` `createInstance(java.util.Date date)` Factory method that returns an instance of a subclass of SerialDate.
`static SerialDate` `createInstance(int serial)` Factory method that returns an instance of some concrete subclass of `SerialDate`.
`static SerialDate` `createInstance(int day, int month, int yyyy)` Factory method that returns an instance of some concrete subclass of `SerialDate`.
`abstract int` `getDayOfMonth()` Returns the day of the month.
`abstract int` `getDayOfWeek()` Returns the day of the week.
`java.lang.String` `getDescription()` Returns the description that is attached to the date.
`SerialDate` `getEndOfCurrentMonth(SerialDate base)` Rolls the date forward to the last day of the month.
`SerialDate` `getFollowingDayOfWeek(int targetDOW)` Returns the earliest date that falls on the specified day-of-the-week and is AFTER this date.
`static SerialDate` `getFollowingDayOfWeek(int targetWeekday, SerialDate base)` Returns the earliest date that falls on the specified day-of-the-week and is AFTER the base date.
`abstract int` `getMonth()` Returns the month (January = 1, February = 2, March = 3).
`static java.lang.String[]` `getMonths()` Returns an array of month names.
`static java.lang.String[]` `getMonths(boolean shortened)` Returns an array of month names.
`SerialDate` `getNearestDayOfWeek(int targetDOW)` Returns the nearest date that falls on the specified day-of-the-week.
`static SerialDate` `getNearestDayOfWeek(int targetDOW, SerialDate base)` Returns the date that falls on the specified day-of-the-week and is CLOSEST to the base date.
`SerialDate` `getPreviousDayOfWeek(int targetDOW)` Returns the latest date that falls on the specified day-of-the-week and is BEFORE this date.
`static SerialDate` `getPreviousDayOfWeek(int targetWeekday, SerialDate base)` Returns the latest date that falls on the specified day-of-the-week and is BEFORE the base date.
`abstract int` `getYYYY()` Returns the year (assume a valid range of 1900 to 9999).
`abstract boolean` `isAfter(SerialDate other)` Returns true if this SerialDate represents the same date as the specified SerialDate.
`abstract boolean` `isBefore(SerialDate other)` Returns true if this SerialDate represents an earlier date compared to the specified SerialDate.
`abstract boolean` `isInRange(SerialDate d1, SerialDate d2)` Returns `true` if this `SerialDate` is within the specified range (INCLUSIVE).
`abstract boolean` `isInRange(SerialDate d1, SerialDate d2, int include)` Returns `true` if this `SerialDate` is within the specified range (caller specifies whether or not the end-points are included).
`static boolean` `isLeapYear(int yyyy)` Determines whether or not the specified year is a leap year.
`abstract boolean` `isOn(SerialDate other)` Returns true if this SerialDate represents the same date as the specified SerialDate.
`abstract boolean` `isOnOrAfter(SerialDate other)` Returns true if this SerialDate represents the same date as the specified SerialDate.
`abstract boolean` `isOnOrBefore(SerialDate other)` Returns true if this SerialDate represents the same date as the specified SerialDate.
`static boolean` `isValidMonthCode(int code)` Returns true if the supplied integer code represents a valid month.
`static boolean` `isValidWeekdayCode(int code)` Returns `true` if the supplied integer code represents a valid day-of-the-week, and `false` otherwise.
`static boolean` `isValidWeekInMonthCode(int code)` Returns true if the supplied integer code represents a valid week-in-the-month, and false otherwise.
`static int` `lastDayOfMonth(int month, int yyyy)` Returns the number of the last day of the month, taking into account leap years.
`static int` `leapYearCount(int yyyy)` Returns the number of leap years from 1900 to the specified year INCLUSIVE.
`static int` `monthCodeToQuarter(int code)` Returns the quarter for the specified month.
`static java.lang.String` `monthCodeToString(int month)` Returns a string representing the supplied month.
`static java.lang.String` `monthCodeToString(int month, boolean shortened)` Returns a string representing the supplied month.
`static java.lang.String` `relativeToString(int relative)` Returns a string representing the supplied 'relative'.
`void` `setDescription(java.lang.String description)` Sets the description for the date.
`static int` `stringToMonthCode(java.lang.String s)` Converts a string to a month code.
`static int` `stringToWeekdayCode(java.lang.String s)` Converts the supplied string to a day of the week.
`abstract java.util.Date` `toDate()` Returns a java.util.Date.
`abstract int` `toSerial()` Returns the serial number for the date, where 1 January 1900 = 2 (this corresponds, almost, to the numbering system used in Microsoft Excel for Windows and Lotus 1-2-3).
`java.lang.String` `toString()` Converts the date to a string.
`static java.lang.String` `weekdayCodeToString(int weekday)` Returns a string representing the supplied day-of-the-week.
`static java.lang.String` `weekInMonthToString(int count)` Returns a string corresponding to the week-in-the-month code.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Methods inherited from interface java.lang.Comparable
`compareTo`

Field Detail

### DATE_FORMAT_SYMBOLS

    public static final java.text.DateFormatSymbols DATE_FORMAT_SYMBOLS

  Date format symbols.

### SERIAL_LOWER_BOUND

    public static final int SERIAL_LOWER_BOUND

  The serial number for 1 January 1900.

  See Also:
    Constant Field Values

### SERIAL_UPPER_BOUND

    public static final int SERIAL_UPPER_BOUND

  The serial number for 31 December 9999.

  See Also:
    Constant Field Values

### MINIMUM_YEAR_SUPPORTED

    public static final int MINIMUM_YEAR_SUPPORTED

  The lowest year value supported by this date format.

  See Also:
    Constant Field Values

### MAXIMUM_YEAR_SUPPORTED

    public static final int MAXIMUM_YEAR_SUPPORTED

  The highest year value supported by this date format.

  See Also:
    Constant Field Values

### MONDAY

    public static final int MONDAY

  Useful constant for Monday. Equivalent to java.util.Calendar.MONDAY.

  See Also:
    Constant Field Values

### TUESDAY

    public static final int TUESDAY

  Useful constant for Tuesday. Equivalent to java.util.Calendar.TUESDAY.

  See Also:
    Constant Field Values

### WEDNESDAY

    public static final int WEDNESDAY

  Useful constant for Wednesday. Equivalent to java.util.Calendar.WEDNESDAY.

  See Also:
    Constant Field Values

### THURSDAY

    public static final int THURSDAY

  Useful constant for Thrusday. Equivalent to java.util.Calendar.THURSDAY.

  See Also:
    Constant Field Values

### FRIDAY

    public static final int FRIDAY

  Useful constant for Friday. Equivalent to java.util.Calendar.FRIDAY.

  See Also:
    Constant Field Values

### SATURDAY

    public static final int SATURDAY

  Useful constant for Saturday. Equivalent to java.util.Calendar.SATURDAY.

  See Also:
    Constant Field Values

### SUNDAY

    public static final int SUNDAY

  Useful constant for Sunday. Equivalent to java.util.Calendar.SUNDAY.

  See Also:
    Constant Field Values

### FIRST_WEEK_IN_MONTH

    public static final int FIRST_WEEK_IN_MONTH

  A useful constant for referring to the first week in a month.

  See Also:
    Constant Field Values

### SECOND_WEEK_IN_MONTH

    public static final int SECOND_WEEK_IN_MONTH

  A useful constant for referring to the second week in a month.

  See Also:
    Constant Field Values

### THIRD_WEEK_IN_MONTH

    public static final int THIRD_WEEK_IN_MONTH

  A useful constant for referring to the third week in a month.

  See Also:
    Constant Field Values

### FOURTH_WEEK_IN_MONTH

    public static final int FOURTH_WEEK_IN_MONTH

  A useful constant for referring to the fourth week in a month.

  See Also:
    Constant Field Values

### LAST_WEEK_IN_MONTH

    public static final int LAST_WEEK_IN_MONTH

  A useful constant for referring to the last week in a month.

  See Also:
    Constant Field Values

### INCLUDE_NONE

    public static final int INCLUDE_NONE

  Useful range constant.

  See Also:
    Constant Field Values

### INCLUDE_FIRST

    public static final int INCLUDE_FIRST

  Useful range constant.

  See Also:
    Constant Field Values

### INCLUDE_SECOND

    public static final int INCLUDE_SECOND

  Useful range constant.

  See Also:
    Constant Field Values

### INCLUDE_BOTH

    public static final int INCLUDE_BOTH

  Useful range constant.

  See Also:
    Constant Field Values

### PRECEDING

    public static final int PRECEDING

  Useful constant for specifying a day of the week relative to a fixed date.

  See Also:
    Constant Field Values

### NEAREST

    public static final int NEAREST

  Useful constant for specifying a day of the week relative to a fixed date.

  See Also:
    Constant Field Values

### FOLLOWING

    public static final int FOLLOWING

  Useful constant for specifying a day of the week relative to a fixed date.

  See Also:
    Constant Field Values

Constructor Detail

### SerialDate

    protected SerialDate()

  Default constructor.

Method Detail

### isValidWeekdayCode

    public static boolean isValidWeekdayCode(int code)

  Returns `true` if the supplied integer code represents a valid day-of-the-week, and `false` otherwise.

  Parameters:
    `code` - the code being checked for validity.
  Returns:
    `true` if the supplied integer code represents a valid day-of-the-week, and `false` otherwise.

### stringToWeekdayCode

    public static int stringToWeekdayCode(java.lang.String s)

  Converts the supplied string to a day of the week.

  Parameters:
    `s` - a string representing the day of the week.
  Returns:
    `-1` if the string is not convertable, the day of the week otherwise.

### weekdayCodeToString

    public static java.lang.String weekdayCodeToString(int weekday)

  Returns a string representing the supplied day-of-the-week.

  Need to find a better approach.

  Parameters:
    `weekday` - the day of the week.
  Returns:
    a string representing the supplied day-of-the-week.

### getMonths

    public static java.lang.String[] getMonths()

  Returns an array of month names.

  Returns:
    an array of month names.

### getMonths

    public static java.lang.String[] getMonths(boolean shortened)

  Returns an array of month names.

  Parameters:
    `shortened` - a flag indicating that shortened month names should be returned.
  Returns:
    an array of month names.

### isValidMonthCode

    public static boolean isValidMonthCode(int code)

  Returns true if the supplied integer code represents a valid month.

  Parameters:
    `code` - the code being checked for validity.
  Returns:
    `true` if the supplied integer code represents a valid month.

### monthCodeToQuarter

    public static int monthCodeToQuarter(int code)

  Returns the quarter for the specified month.

  Parameters:
    `code` - the month code (1-12).
  Returns:
    the quarter that the month belongs to.

### monthCodeToString

    public static java.lang.String monthCodeToString(int month)

  Returns a string representing the supplied month.

  The string returned is the long form of the month name taken from the default locale.

  Parameters:
    `month` - the month.
  Returns:
    a string representing the supplied month.

### monthCodeToString

    public static java.lang.String monthCodeToString(int month,
                                                     boolean shortened)

  Returns a string representing the supplied month.

  The string returned is the long or short form of the month name taken from the default locale.

  Parameters:
    `month` - the month.
    `shortened` - if `true` return the abbreviation of the month.
  Returns:
    a string representing the supplied month.

### stringToMonthCode

    public static int stringToMonthCode(java.lang.String s)

  Converts a string to a month code.

  This method will return one of the constants JANUARY, FEBRUARY, ..., DECEMBER that corresponds to the string. If the string is not recognised, this method returns -1.

  Parameters:
    `s` - the string to parse.
  Returns:
    `-1` if the string is not parseable, the month of the year otherwise.

### isValidWeekInMonthCode

    public static boolean isValidWeekInMonthCode(int code)

  Returns true if the supplied integer code represents a valid week-in-the-month, and false otherwise.

  Parameters:
    `code` - the code being checked for validity.
  Returns:
    `true` if the supplied integer code represents a valid week-in-the-month.

### isLeapYear

    public static boolean isLeapYear(int yyyy)

  Determines whether or not the specified year is a leap year.

  Parameters:
    `yyyy` - the year (in the range 1900 to 9999).
  Returns:
    `true` if the specified year is a leap year.

### leapYearCount

    public static int leapYearCount(int yyyy)

  Returns the number of leap years from 1900 to the specified year INCLUSIVE.

  Note that 1900 is not a leap year.

  Parameters:
    `yyyy` - the year (in the range 1900 to 9999).
  Returns:
    the number of leap years from 1900 to the specified year.

### lastDayOfMonth

    public static int lastDayOfMonth(int month,
                                     int yyyy)

  Returns the number of the last day of the month, taking into account leap years.

  Parameters:
    `month` - the month.
    `yyyy` - the year (in the range 1900 to 9999).
  Returns:
    the number of the last day of the month.

### addDays

    public static SerialDate addDays(int days,
                                     SerialDate base)

  Creates a new date by adding the specified number of days to the base date.

  Parameters:
    `days` - the number of days to add (can be negative).
    `base` - the base date.
  Returns:
    a new date.

### addMonths

    public static SerialDate addMonths(int months,
                                       SerialDate base)

  Creates a new date by adding the specified number of months to the base date.

  If the base date is close to the end of the month, the day on the result may be adjusted slightly: 31 May + 1 month = 30 June.

  Parameters:
    `months` - the number of months to add (can be negative).
    `base` - the base date.
  Returns:
    a new date.

### addYears

    public static SerialDate addYears(int years,
                                      SerialDate base)

  Creates a new date by adding the specified number of years to the base date.

  Parameters:
    `years` - the number of years to add (can be negative).
    `base` - the base date.
  Returns:
    A new date.

### getPreviousDayOfWeek

    public static SerialDate getPreviousDayOfWeek(int targetWeekday,
                                                  SerialDate base)

  Returns the latest date that falls on the specified day-of-the-week and is BEFORE the base date.

  Parameters:
    `targetWeekday` - a code for the target day-of-the-week.
    `base` - the base date.
  Returns:
    the latest date that falls on the specified day-of-the-week and is BEFORE the base date.

### getFollowingDayOfWeek

    public static SerialDate getFollowingDayOfWeek(int targetWeekday,
                                                   SerialDate base)

  Returns the earliest date that falls on the specified day-of-the-week and is AFTER the base date.

  Parameters:
    `targetWeekday` - a code for the target day-of-the-week.
    `base` - the base date.
  Returns:
    the earliest date that falls on the specified day-of-the-week and is AFTER the base date.

### getNearestDayOfWeek

    public static SerialDate getNearestDayOfWeek(int targetDOW,
                                                 SerialDate base)

  Returns the date that falls on the specified day-of-the-week and is CLOSEST to the base date.

  Parameters:
    `targetDOW` - a code for the target day-of-the-week.
    `base` - the base date.
  Returns:
    the date that falls on the specified day-of-the-week and is CLOSEST to the base date.

### getEndOfCurrentMonth

    public SerialDate getEndOfCurrentMonth(SerialDate base)

  Rolls the date forward to the last day of the month.

  Parameters:
    `base` - the base date.
  Returns:
    a new serial date.

### weekInMonthToString

    public static java.lang.String weekInMonthToString(int count)

  Returns a string corresponding to the week-in-the-month code.

  Need to find a better approach.

  Parameters:
    `count` - an integer code representing the week-in-the-month.
  Returns:
    a string corresponding to the week-in-the-month code.

### relativeToString

    public static java.lang.String relativeToString(int relative)

  Returns a string representing the supplied 'relative'.

  Need to find a better approach.

  Parameters:
    `relative` - a constant representing the 'relative'.
  Returns:
    a string representing the supplied 'relative'.

### createInstance

    public static SerialDate createInstance(int day,
                                            int month,
                                            int yyyy)

  Factory method that returns an instance of some concrete subclass of `SerialDate`.

  Parameters:
    `day` - the day (1-31).
    `month` - the month (1-12).
    `yyyy` - the year (in the range 1900 to 9999).
  Returns:
    An instance of `SerialDate`.

### createInstance

    public static SerialDate createInstance(int serial)

  Factory method that returns an instance of some concrete subclass of `SerialDate`.

  Parameters:
    `serial` - the serial number for the day (1 January 1900 = 2).
  Returns:
    a instance of SerialDate.

### createInstance

    public static SerialDate createInstance(java.util.Date date)

  Factory method that returns an instance of a subclass of SerialDate.

  Parameters:
    `date` - A Java date object.
  Returns:
    a instance of SerialDate.

### toSerial

    public abstract int toSerial()

  Returns the serial number for the date, where 1 January 1900 = 2 (this corresponds, almost, to the numbering system used in Microsoft Excel for Windows and Lotus 1-2-3).

  Returns:
    the serial number for the date.

### toDate

    public abstract java.util.Date toDate()

  Returns a java.util.Date. Since java.util.Date has more precision than SerialDate, we need to define a convention for the 'time of day'.

  Returns:
    this as `java.util.Date`.

### getDescription

    public java.lang.String getDescription()

  Returns the description that is attached to the date. It is not required that a date have a description, but for some applications it is useful.

  Returns:
    The description (possibly `null`).

### setDescription

    public void setDescription(java.lang.String description)

  Sets the description for the date.

  Parameters:
    `description` - the description for this date (`null` permitted).

### toString

    public java.lang.String toString()

  Converts the date to a string.

  Overrides:
    `toString` in class `java.lang.Object`
  Returns:
    a string representation of the date.

### getYYYY

    public abstract int getYYYY()

  Returns the year (assume a valid range of 1900 to 9999).

  Returns:
    the year.

### getMonth

    public abstract int getMonth()

  Returns the month (January = 1, February = 2, March = 3).

  Returns:
    the month of the year.

### getDayOfMonth

    public abstract int getDayOfMonth()

  Returns the day of the month.

  Returns:
    the day of the month.

### getDayOfWeek

    public abstract int getDayOfWeek()

  Returns the day of the week.

  Returns:
    the day of the week.

### compare

    public abstract int compare(SerialDate other)

  Returns the difference (in days) between this date and the specified 'other' date.

  The result is positive if this date is after the 'other' date and negative if it is before the 'other' date.

  Parameters:
    `other` - the date being compared to.
  Returns:
    the difference between this and the other date.

### isOn

    public abstract boolean isOn(SerialDate other)

  Returns true if this SerialDate represents the same date as the specified SerialDate.

  Parameters:
    `other` - the date being compared to.
  Returns:
    `true` if this SerialDate represents the same date as the specified SerialDate.

### isBefore

    public abstract boolean isBefore(SerialDate other)

  Returns true if this SerialDate represents an earlier date compared to the specified SerialDate.

  Parameters:
    `other` - The date being compared to.
  Returns:
    `true` if this SerialDate represents an earlier date compared to the specified SerialDate.

### isOnOrBefore

    public abstract boolean isOnOrBefore(SerialDate other)

  Returns true if this SerialDate represents the same date as the specified SerialDate.

  Parameters:
    `other` - the date being compared to.
  Returns:
    `true`if this SerialDate represents the same date as the specified SerialDate.``

### isAfter

    public abstract boolean isAfter(SerialDate other)

  Returns true if this SerialDate represents the same date as the specified SerialDate.

  Parameters:
    `other` - the date being compared to.
  Returns:
    `true` if this SerialDate represents the same date as the specified SerialDate.

### isOnOrAfter

    public abstract boolean isOnOrAfter(SerialDate other)

  Returns true if this SerialDate represents the same date as the specified SerialDate.

  Parameters:
    `other` - the date being compared to.
  Returns:
    `true` if this SerialDate represents the same date as the specified SerialDate.

### isInRange

    public abstract boolean isInRange(SerialDate d1,
                                      SerialDate d2)

  Returns `true` if this `SerialDate` is within the specified range (INCLUSIVE). The date order of d1 and d2 is not important.

  Parameters:
    `d1` - a boundary date for the range.
    `d2` - the other boundary date for the range.
  Returns:
    A boolean.

### isInRange

    public abstract boolean isInRange(SerialDate d1,
                                      SerialDate d2,
                                      int include)

  Returns `true` if this `SerialDate` is within the specified range (caller specifies whether or not the end-points are included). The date order of d1 and d2 is not important.

  Parameters:
    `d1` - a boundary date for the range.
    `d2` - the other boundary date for the range.
    `include` - a code that controls whether or not the start and end dates are included in the range.
  Returns:
    A boolean.

### getPreviousDayOfWeek

    public SerialDate getPreviousDayOfWeek(int targetDOW)

  Returns the latest date that falls on the specified day-of-the-week and is BEFORE this date.

  Parameters:
    `targetDOW` - a code for the target day-of-the-week.
  Returns:
    the latest date that falls on the specified day-of-the-week and is BEFORE this date.

### getFollowingDayOfWeek

    public SerialDate getFollowingDayOfWeek(int targetDOW)

  Returns the earliest date that falls on the specified day-of-the-week and is AFTER this date.

  Parameters:
    `targetDOW` - a code for the target day-of-the-week.
  Returns:
    the earliest date that falls on the specified day-of-the-week and is AFTER this date.

### getNearestDayOfWeek

    public SerialDate getNearestDayOfWeek(int targetDOW)

  Returns the nearest date that falls on the specified day-of-the-week.

  Parameters:
    `targetDOW` - a code for the target day-of-the-week.
  Returns:
    the nearest date that falls on the specified day-of-the-week.