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## com.trolltech.qt.core
Class QDate

    java.lang.Object
      com.trolltech.qt.internal.QSignalEmitterInternal
          com.trolltech.qt.QSignalEmitter
              com.trolltech.qt.QtJambiObject
                  com.trolltech.qt.core.QDate

All Implemented Interfaces:
  QtJambiInterface, java.lang.Cloneable, java.lang.Comparable

    public class QDate

extends QtJambiObject
implements java.lang.Comparable, java.lang.Cloneable

The QDate class provides date functions. A QDate object contains a calendar date, i.e. year, month, and day numbers, in the Gregorian calendar. (see Use of Gregorian and Julian Calendars for dates prior to 15 October 1582). It can read the current date from the system clock. It provides functions for comparing dates, and for manipulating dates. For example, it is possible to add and subtract days, months, and years to dates.

A QDate object is typically created either by giving the year, month, and day numbers explicitly. Note that QDate interprets two digit years to be in the 1900s, e.g., 50 will equals 1950. A QDate can also be constructed with the static function `currentDate()`, which creates a QDate object containing the system clock's date. An explicit date can also be set using `setDate()`. The `fromString()` function returns a QDate given a string and a date format which is used to interpret the date within the string.

The `year()`, `month()`, and `day()` functions provide access to the year, month, and day numbers. Also, `dayOfWeek()` and `dayOfYear()` functions are provided. The same information is provided in textual format by the `toString()`, `shortDayName()`, `longDayName()`, `shortMonthName()`, and `longMonthName()` functions.

QDate provides a full set of operators to compare two QDate objects where smaller means earlier, and larger means later.

You can increment (or decrement) a date by a given number of days using `addDays()`. Similarly you can use `addMonths()` and `addYears()`. The `daysTo()` function returns the number of days between two dates.

The `daysInMonth()` and `daysInYear()` functions return how many days there are in this date's month and year, respectively. The `isLeapYear()` function indicates whether a date is in a leap year.

### Use of Gregorian and Julian Calendars

QDate uses the Gregorian calendar in all locales, beginning on the date 15 October 1582. For dates up to and including 4 October 1582, the Julian calendar is used. This means there is a 10-day gap in the internal calendar between the 4th and the 15th of October 1582. When you use `QDateTime` for dates in that epoch, the day after 4 October 1582 is 15 October 1582, and the dates in the gap are invalid.

The Julian to Gregorian changeover date used here is the date when the Gregorian calendar was first introduced, by Pope Gregory XIII. That change was not universally accepted and some localities only executed it at a later date (if at all). `QDateTime` doesn't take any of these historical facts into account. If an application must support a locale-specific dating system, it must do so on its own, remembering to convert the dates using the Julian day.

### No Year 0

There is no year 0. Dates in that year are considered invalid. The year -1 is the year "1 before Christ" or "1 before current era." The day before 0001-01-01 is December 31st, 1 BCE.

### Range of Valid Dates

The range of valid dates is from January 2nd, 4713 BCE, to sometime in the year 11 million CE. The Julian Day returned by `QDate::toJulianDay()` is a number in the contiguous range from 1 to overflow, even across `QDateTime`'s "date holes". It is suitable for use in applications that must convert a `QDateTime` to a date in another calendar system, e.g., Hebrew, Islamic or Chinese.

See also:
  `QTime`, `QDateTime`, `QDateEdit`, `QDateTimeEdit`, and `QCalendarWidget`.

Nested Class Summary

Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
`QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9`

Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal`

Field Summary

Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`currentSender`

Constructor Summary
`QDate()` Constructs a null date.
`QDate(int y, int m, int d)` Constructs a date with year `y`, month `m` and day `d`.

Method Summary
`QDate` | `addDays(int days)` Returns a QDate object containing a date `ndays` later than the date of this object (or earlier if `ndays` is negative).
`QDate` | `addMonths(int months)` Returns a QDate object containing a date `nmonths` later than the date of this object (or earlier if `nmonths` is negative).
`QDate` | `addYears(int years)` Returns a QDate object containing a date `nyears` later than the date of this object (or earlier if `nyears` is negative).
`QDate` | `clone()` This method is reimplemented for internal reasons
`static QDate` | `currentDate()` Returns the current date, as reported by the system clock.
`int` | `day()` Returns the day of the month (1 to 31) of this date.
`int` | `dayOfWeek()` Returns the weekday (1 to 7) for this date.
`int` | `dayOfYear()` Returns the day of the year (1 to 365 or 366 on leap years) for this date.
`int` | `daysInMonth()` Returns the number of days in the month (28 to 31) for this date.
`int` | `daysInYear()` Returns the number of days in the year (365 or 366) for this date.
`int` | `daysTo(QDate arg__1)` Returns the number of days from this date to `d` (which is negative if `d` is earlier than this date).
`static QDate` | `fromJulianDay(int jd)` Converts the Julian day `jd` to a QDate.
`static QDate` | `fromString(java.lang.String s)` Returns the QDate represented by the `string`, using the `format` given, or an invalid date if the string cannot be parsed.
`static QDate` | `fromString(java.lang.String s, Qt.DateFormat f)` Returns the QDate represented by the `string`, using the `format` given, or an invalid date if the string cannot be parsed.
`static QDate` | `fromString(java.lang.String s, java.lang.String format)` Returns the QDate represented by the `string`, using the `format` given, or an invalid date if the string cannot be parsed.
`static boolean` | `isLeapYear(int year)` Returns true if the specified `year` is a leap year; otherwise returns false.
`boolean` | `isNull()` Returns true if the date is null; otherwise returns false.
`boolean` | `isValid()` Returns true if this date is valid; otherwise returns false.
`static boolean` | `isValid(int y, int m, int d)` Returns true if the specified date (`year`, `month`, and `day`) is valid; otherwise returns false.
`static java.lang.String` | `longDayName(int weekday)` Returns the long name of the `weekday` using the following convention.
`static java.lang.String` | `longMonthName(int month)` Returns the long name of the `month` using the following convention.
`int` | `month()` Returns the number corresponding to the month of this date, using the following convention.
`void` | `readFrom(QDataStream arg__1)` Reads a QDate
`boolean` | `setDate(int year, int month, int date)` Sets the date's `year`, `month`, and `day`.
`static java.lang.String` | `shortDayName(int weekday)` Returns the name of the `weekday` using the following convention.
`static java.lang.String` | `shortMonthName(int month)` Returns the name of the `month` using the following convention.
`int` | `toJulianDay()` Converts the date to a Julian day.
`java.lang.String` | `toString()` Returns a string representation of the `this QDate`.
`java.lang.String` | `toString(Qt.DateFormat f)` Returns a string representation of the `com.trolltech.qt.core.Qt$DateFormat` argument.
`java.lang.String` | `toString(java.lang.String format)` Returns a string representation of the `java.lang.String` argument.
`int` | `weekNumber()` Returns the week number (1 to 53).
`void` | `writeTo(QDataStream arg__1)` Writes thisQDate
`int` | `year()` Returns the year of this date.
`int` | `yearOfWeekNumber()` This function returns the year number of the QDate's current week.

Methods inherited from class com.trolltech.qt.QtJambiObject
`dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr`

Methods inherited from class com.trolltech.qt.QSignalEmitter
`blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread`

Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`__qt_signalInitialization`

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

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

Methods inherited from interface com.trolltech.qt.QtJambiInterface
`disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership`

Constructor Detail

### QDate

    public QDate()

  Constructs a null date. Null dates are invalid.

See also:
  `isNull()`, and `isValid()`.

### QDate

    public QDate(int y,
                 int m,
                 int d)

  Constructs a date with year `y`, month `m` and day `d`.

  If the specified date is invalid, the date is not set and `isValid()` returns false. A date before 2 January 4713 B.C. is considered invalid.

  Warning: Years 1 to 99 are interpreted as being in the 1900s. If you want to specify the year 2010, you must write 2010, not 10.

See also:
  `isValid()`.

Method Detail

### addDays

    public final QDate addDays(int days)

  Returns a QDate object containing a date `ndays` later than the date of this object (or earlier if `ndays` is negative).

See also:
  `addMonths()`, `addYears()`, and `daysTo()`.

### addMonths

    public final QDate addMonths(int months)

  Returns a QDate object containing a date `nmonths` later than the date of this object (or earlier if `nmonths` is negative).

See also:
  `addDays()`, and `addYears()`.

### addYears

    public final QDate addYears(int years)

  Returns a QDate object containing a date `nyears` later than the date of this object (or earlier if `nyears` is negative).

See also:
  `addDays()`, and `addMonths()`.

### day

    public final int day()

  Returns the day of the month (1 to 31) of this date.

See also:
  `year()`, `month()`, and `dayOfWeek()`.

### dayOfWeek

    public final int dayOfWeek()

  Returns the weekday (1 to 7) for this date.

See also:
  `day()`, `dayOfYear()`, and `Qt::DayOfWeek` .

### dayOfYear

    public final int dayOfYear()

  Returns the day of the year (1 to 365 or 366 on leap years) for this date.

See also:
  `day()`, and `dayOfWeek()`.

### daysInMonth

    public final int daysInMonth()

  Returns the number of days in the month (28 to 31) for this date.

See also:
  `day()`, and `daysInYear()`.

### daysInYear

    public final int daysInYear()

  Returns the number of days in the year (365 or 366) for this date.

See also:
  `day()`, and `daysInMonth()`.

### daysTo

    public final int daysTo(QDate arg__1)

  Returns the number of days from this date to `d` (which is negative if `d` is earlier than this date).

  Example:

              QDate d1 = new QDate(1995, 5, 17);  // May 17, 1995
              QDate d2 = new QDate(1995, 5, 20);  // May 20, 1995
              d1.daysTo(d2);          // returns 3
              d2.daysTo(d1);          // returns -3

See also:
  `addDays()`.

### isNull

    public final boolean isNull()

  Returns true if the date is null; otherwise returns false. A null date is invalid.

  Note: The behavior of this function is identical to `isValid()`.

See also:
  `isValid()`.

### isValid

    public final boolean isValid()

  Returns true if this date is valid; otherwise returns false.

See also:
  `isNull()`.

### month

    public final int month()

  Returns the number corresponding to the month of this date, using the following convention.
  - 1 = "January"
  - 2 = "February"
  - 3 = "March"
  - 4 = "April"
  - 5 = "May"
  - 6 = "June"
  - 7 = "July"
  - 8 = "August"
  - 9 = "September"
  - 10 = "October"
  - 11 = "November"
  - 12 = "December"

See also:
  `year()`, and `day()`.

### writeTo

    public final void writeTo(QDataStream arg__1)

  Writes thisQDate

### readFrom

    public final void readFrom(QDataStream arg__1)

  Reads a QDate

### setDate

    public final boolean setDate(int year,
                                 int month,
                                 int date)

  Sets the date's `year`, `month`, and `day`. Returns true if the date is valid; otherwise returns false.

  If the specified date is invalid, the QDate object is set to be invalid. Any date before 2 January 4713 B.C. is considered invalid.

See also:
  `isValid()`.

### toJulianDay

    public final int toJulianDay()

  Converts the date to a Julian day.

See also:
  `fromJulianDay()`.

### toString

    public final java.lang.String toString()

  Returns a string representation of the `this QDate`.

  Overrides:
    `toString` in class `java.lang.Object`

### toString

    public final java.lang.String toString(Qt.DateFormat f)

  Returns a string representation of the `com.trolltech.qt.core.Qt$DateFormat` argument.

### toString

    public final java.lang.String toString(java.lang.String format)

  Returns a string representation of the `java.lang.String` argument.

### year

    public final int year()

  Returns the year of this date. Negative numbers indicate years before 1 A.D. = 1 C.E., such that year -44 is 44 B.C.

See also:
  `month()`, and `day()`.

### currentDate

    public static QDate currentDate()

  Returns the current date, as reported by the system clock.

See also:
  `QTime::currentTime()`, and `QDateTime::currentDateTime()`.

### fromJulianDay

    public static QDate fromJulianDay(int jd)

  Converts the Julian day `jd` to a QDate.

See also:
  `toJulianDay()`.

### fromString

    public static QDate fromString(java.lang.String s)

  Returns the QDate represented by the `string`, using the `format` given, or an invalid date if the string cannot be parsed.

  Note that years specified with two digits are interpreted to be between 1900 and 1999.

  Note for `Qt::TextDate` : It is recommended that you use the English short month names (e.g. "Jan"). Although localized month names can also be used, they depend on the user's locale settings.

### fromString

    public static QDate fromString(java.lang.String s,
                                   Qt.DateFormat f)

  Returns the QDate represented by the `string`, using the `format` given, or an invalid date if the string cannot be parsed.

  Note that years specified with two digits are interpreted to be between 1900 and 1999.

  Note for `Qt::TextDate` : It is recommended that you use the English short month names (e.g. "Jan"). Although localized month names can also be used, they depend on the user's locale settings.

### fromString

    public static QDate fromString(java.lang.String s,
                                   java.lang.String format)

  Returns the QDate represented by the `string`, using the `format` given, or an invalid date if the string cannot be parsed.

  These expressions may be used for the format:

  Expression | Output
  --- | ---
  d | The day as a number without a leading zero (1 to 31)
  dd | The day as a number with a leading zero (01 to 31)
  ddd | The abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses `QDate::shortDayName()`.
  dddd | The long localized day name (e.g. 'Monday' to 'Sunday'). Uses `QDate::longDayName()`.
  M | The month as a number without a leading zero (1 to 12)
  MM | The month as a number with a leading zero (01 to 12)
  MMM | The abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses `QDate::shortMonthName()`.
  MMMM | The long localized month name (e.g. 'January' to 'December'). Uses `QDate::longMonthName()`.
  yy | The year as two digit number (00 to 99)
  yyyy | The year as four digit number. If the year is negative, a minus sign is prepended in addition.

  All other input characters will be treated as text. Any sequence of characters that are enclosed in single quotes will also be treated as text and will not be used as an expression. For example:

              QDate date = QDate.fromString("1MM12car2003", "d'MM'MMcaryyyy");
              // date is 1 December 2003

  If the format is not satisfied, an invalid QDate is returned. The expressions that don't expect leading zeroes (d, M) will be greedy. This means that they will use two digits even if this will put them outside the accepted range of values and leaves too few digits for other sections. For example, the following format string could have meant January 30 but the M will grab two digits, resulting in an invalid date:

              QDate date = QDate.fromString("130", "Md"); // invalid

  For any field that is not represented in the format the following defaults are used:

  Field | Default value
  --- | ---
  Year | 1900
  Month | 1
  Day | 1

  The following examples demonstrate the default values:

              QDate.fromString("1.30", "M.d");           // January 30 1900
              QDate.fromString("20000110", "yyyyMMdd");  // January 10, 2000
              QDate.fromString("20000110", "yyyyMd");    // January 10, 2000

See also:
  `QDateTime::fromString()`, `QTime::fromString()`, `QDate::toString()`, `QDateTime::toString()`, and `QTime::toString()`.

### isLeapYear

    public static boolean isLeapYear(int year)

  Returns true if the specified `year` is a leap year; otherwise returns false.

### isValid

    public static boolean isValid(int y,
                                  int m,
                                  int d)

  Returns true if the specified date (`year`, `month`, and `day`) is valid; otherwise returns false.

  Example:

              QDate.isValid(2002, 5, 17);  // true
              QDate.isValid(2002, 2, 30);  // false (Feb 30 does not exist)
              QDate.isValid(2004, 2, 29);  // true (2004 is a leap year)
              QDate.isValid(2000, 2, 29);  // true (2000 is a leap year)
              QDate.isValid(2006, 2, 29);  // false (2006 is not a leap year)
              QDate.isValid(2100, 2, 29);  // false (2100 is not a leap year)
              QDate.isValid(1202, 6, 6);   // true (even though 1202 is pre-Gregorian)

See also:
  `isNull()`, and `setDate()`.

### longDayName

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

  Returns the long name of the `weekday` using the following convention.
  - 1 = "Monday"
  - 2 = "Tuesday"
  - 3 = "Wednesday"
  - 4 = "Thursday"
  - 5 = "Friday"
  - 6 = "Saturday"
  - 7 = "Sunday"
  The day names will be localized according to the system's locale settings.

See also:
  `toString()`, `shortDayName()`, `shortMonthName()`, and `longMonthName()`.

### longMonthName

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

  Returns the long name of the `month` using the following convention.
  - 1 = "January"
  - 2 = "February"
  - 3 = "March"
  - 4 = "April"
  - 5 = "May"
  - 6 = "June"
  - 7 = "July"
  - 8 = "August"
  - 9 = "September"
  - 10 = "October"
  - 11 = "November"
  - 12 = "December"
  The month names will be localized according to the system's locale settings.

See also:
  `toString()`, `shortMonthName()`, `shortDayName()`, and `longDayName()`.

### shortDayName

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

  Returns the name of the `weekday` using the following convention.
  - 1 = "Mon"
  - 2 = "Tue"
  - 3 = "Wed"
  - 4 = "Thu"
  - 5 = "Fri"
  - 6 = "Sat"
  - 7 = "Sun"
  The day names will be localized according to the system's locale settings.

See also:
  `toString()`, `shortMonthName()`, `longMonthName()`, and `longDayName()`.

### shortMonthName

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

  Returns the name of the `month` using the following convention.
  - 1 = "Jan"
  - 2 = "Feb"
  - 3 = "Mar"
  - 4 = "Apr"
  - 5 = "May"
  - 6 = "Jun"
  - 7 = "Jul"
  - 8 = "Aug"
  - 9 = "Sep"
  - 10 = "Oct"
  - 11 = "Nov"
  - 12 = "Dec"
  The month names will be localized according to the system's locale settings.

See also:
  `toString()`, `longMonthName()`, `shortDayName()`, and `longDayName()`.

### weekNumber

    public final int weekNumber()

  Returns the week number (1 to 53).

  Returns null if the date is invalid.

  In accordance with ISO 8601, weeks start on Qt.DayOfWeek.Monday and the first Qt.DayOfWeek.Thursday of a year is always in week 1 of that year. Most years have 52 weeks, but some have 53.

  Copyright (c) 1989 The Regents of the University of California. All rights reserved.

  Redistribution and use in source and binary forms are permitted provided that the above copyright notice and this paragraph are duplicated in all such forms and that any documentation, advertising materials, and other materials related to such distribution and use acknowledge that the software was developed by the University of California, Berkeley. The name of the University may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

### yearOfWeekNumber

    public final int yearOfWeekNumber()

  This function returns the year number of the QDate's current week.

### clone

    public QDate clone()

  This method is reimplemented for internal reasons

  Overrides:
    `clone` in class `java.lang.Object`

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