org.apache.tapestry5.ioc.internal.services.cron

## Class CronExpression

- java.lang.Object
- - org.apache.tapestry5.ioc.internal.services.cron.CronExpression

- All Implemented Interfaces:
    Serializable

      public class CronExpression
      extends Object
      implements Serializable

  Provides a parser and evaluator for unix-like cron expressions. Cron expressions provide the ability to specify complex time combinations such as "At 8:00am every Monday through Friday" or "At 1:30am every last Friday of the month". Cron expressions are comprised of 6 required fields and one optional field separated by white space. The fields respectively are described as follows:

  Field Name |  | Allowed Values | Allowed Special Characters
  --- | --- | --- | ---
  `Seconds` |  | `0-59` | `, - * /`
  `Minutes` |  | `0-59` | `, - * /`
  `Hours` |  | `0-23` | `, - * /`
  `Day-of-month` |  | `1-31` | `, - * ? / L W`
  `Month` |  | `1-12 or JAN-DEC` | `, - * /`
  `Day-of-Week` |  | `1-7 or SUN-SAT` | `, - * ? / L #`
  `Year (Optional)` |  | `empty, 1970-2199` | `, - * /`
  Cron Expressions

  The '*' character is used to specify all values. For example, "*" in the minute field means "every minute". The '?' character is allowed for the day-of-month and day-of-week fields. It is used to specify 'no specific value'. This is useful when you need to specify something in one of the two fields, but not the other. The '-' character is used to specify ranges For example "10-12" in the hour field means "the hours 10, 11 and 12". The ',' character is used to specify additional values. For example "MON,WED,FRI" in the day-of-week field means "the days Monday, Wednesday, and Friday". The '/' character is used to specify increments. For example "0/15" in the seconds field means "the seconds 0, 15, 30, and 45". And "5/15" in the seconds field means "the seconds 5, 20, 35, and 50". Specifying '*' before the '/' is equivalent to specifying 0 is the value to start with. Essentially, for each field in the expression, there is a set of numbers that can be turned on or off. For seconds and minutes, the numbers range from 0 to 59. For hours 0 to 23, for days of the month 0 to 31, and for months 1 to 12. The "/" character simply helps you turn on every "nth" value in the given set. Thus "7/6" in the month field only turns on month "7", it does NOT mean every 6th month, please note that subtlety. The 'L' character is allowed for the day-of-month and day-of-week fields. This character is short-hand for "last", but it has different meaning in each of the two fields. For example, the value "L" in the day-of-month field means "the last day of the month" - day 31 for January, day 28 for February on non-leap years. If used in the day-of-week field by itself, it simply means "7" or "SAT". But if used in the day-of-week field after another value, it means "the last xxx day of the month" - for example "6L" means "the last friday of the month". You can also specify an offset from the last day of the month, such as "L-3" which would mean the third-to-last day of the calendar month. When using the 'L' option, it is important not to specify lists, or ranges of values, as you'll get confusing/unexpected results. The 'W' character is allowed for the day-of-month field. This character is used to specify the weekday (Monday-Friday) nearest the given day. As an example, if you were to specify "15W" as the value for the day-of-month field, the meaning is: "the nearest weekday to the 15th of the month". So if the 15th is a Saturday, the trigger will fire on Friday the 14th. If the 15th is a Sunday, the trigger will fire on Monday the 16th. If the 15th is a Tuesday, then it will fire on Tuesday the 15th. However if you specify "1W" as the value for day-of-month, and the 1st is a Saturday, the trigger will fire on Monday the 3rd, as it will not 'jump' over the boundary of a month's days. The 'W' character can only be specified when the day-of-month is a single day, not a range or list of days. The 'L' and 'W' characters can also be combined for the day-of-month expression to yield 'LW', which translates to "last weekday of the month". The '#' character is allowed for the day-of-week field. This character is used to specify "the nth" XXX day of the month. For example, the value of "6#3" in the day-of-week field means the third Friday of the month (day 6 = Friday and "#3" = the 3rd one in the month). Other examples: "2#1" = the first Monday of the month and "4#5" = the fifth Wednesday of the month. Note that if you specify "#5" and there is not 5 of the given day-of-week in the month, then no firing will occur that month. If the '#' character is used, there can only be one expression in the day-of-week field ("3#1,6#3" is not valid, since there are two expressions). The legal characters and the names of months and days of the week are not case sensitive. NOTES:
  - Support for specifying both a day-of-week and a day-of-month value is not complete (you'll need to use the '?' character in one of these fields).
  - Overflowing ranges is supported - that is, having a larger number on the left hand side than the right. You might do 22-2 to catch 10 o'clock at night until 2 o'clock in the morning, or you might have NOV-FEB. It is very important to note that overuse of overflowing ranges creates ranges that don't make sense and no effort has been made to determine which interpretation CronExpression chooses. An example would be "0 0 14-6 ? * FRI-MON".
  See Also:
    Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected static Integer` | `ALL_SPEC`
    `protected static int` | `ALL_SPEC_INT`
    `protected static int` | `DAY_OF_MONTH`
    `protected static int` | `DAY_OF_WEEK`
    `protected static Map` | `dayMap`
    `protected TreeSet<Integer>` | `daysOfMonth`
    `protected TreeSet<Integer>` | `daysOfWeek`
    `protected boolean` | `expressionParsed`
    `protected static int` | `HOUR`
    `protected TreeSet<Integer>` | `hours`
    `protected int` | `lastdayOffset`
    `protected boolean` | `lastdayOfMonth`
    `protected boolean` | `lastdayOfWeek`
    `static int` | `MAX_YEAR`
    `protected static int` | `MINUTE`
    `protected TreeSet<Integer>` | `minutes`
    `protected static int` | `MONTH`
    `protected static Map` | `monthMap`
    `protected TreeSet<Integer>` | `months`
    `protected boolean` | `nearestWeekday`
    `protected static Integer` | `NO_SPEC`
    `protected static int` | `NO_SPEC_INT`
    `protected int` | `nthdayOfWeek`
    `protected static int` | `SECOND`
    `protected TreeSet<Integer>` | `seconds`
    `protected static int` | `YEAR`
    `protected TreeSet<Integer>` | `years`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `CronExpression(String cronExpression)` Constructs a new `CronExpression` based on the specified parameter.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected void` | `addToSet(int val, int end, int incr, int type)`
    `protected void` | `buildExpression(String expression)`
    `protected int` | `checkNext(int pos, String s, int val, int type)`
    `protected int` | `findNextWhiteSpace(int i, String s)`
    `String` | `getCronExpression()`
    `protected int` | `getDayOfWeekNumber(String s)`
    `Date` | `getFinalFireTime()` NOT YET IMPLEMENTED: Returns the final time that the `CronExpression` will match.
    `protected int` | `getLastDayOfMonth(int monthNum, int year)`
    `protected int` | `getMonthNumber(String s)`
    `Date` | `getNextInvalidTimeAfter(Date date)` Returns the next date/time after the given date/time which does not satisfy the expression
    `Date` | `getNextValidTimeAfter(Date date)` Returns the next date/time after the given date/time which satisfies the cron expression.
    `protected int` | `getNumericValue(String s, int i)`
    `protected TreeSet<Integer>` | `getSet(int type)`
    `Date` | `getTimeAfter(Date afterTime)`
    `Date` | `getTimeBefore(Date endTime)` NOT YET IMPLEMENTED: Returns the time before the given time that the `CronExpression` matches.
    `TimeZone` | `getTimeZone()` Returns the time zone for which this `CronExpression` will be resolved.
    `protected org.apache.tapestry5.ioc.internal.services.cron.ValueSet` | `getValue(int v, String s, int i)`
    `protected boolean` | `isLeapYear(int year)`
    `boolean` | `isSatisfiedBy(Date date)` Indicates whether the given date satisfies the cron expression.
    `static boolean` | `isValidExpression(String cronExpression)` Indicates whether the specified cron expression can be parsed into a valid cron expression
    `protected void` | `setCalendarHour(Calendar cal, int hour)` Advance the calendar to the particular hour paying particular attention to daylight saving problems.
    `void` | `setTimeZone(TimeZone timeZone)` Sets the time zone for which this `CronExpression` will be resolved.
    `protected int` | `skipWhiteSpace(int i, String s)`
    `protected int` | `storeExpressionVals(int pos, String s, int type)`
    `String` | `toString()` Returns the string representation of the `CronExpression`
    `static void` | `validateExpression(String cronExpression)`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### SECOND

          protected static final int SECOND

      See Also:
        Constant Field Values

    - #### MINUTE

          protected static final int MINUTE

      See Also:
        Constant Field Values

    - #### HOUR

          protected static final int HOUR

      See Also:
        Constant Field Values

    - #### DAY_OF_MONTH

          protected static final int DAY_OF_MONTH

      See Also:
        Constant Field Values

    - #### MONTH

          protected static final int MONTH

      See Also:
        Constant Field Values

    - #### DAY_OF_WEEK

          protected static final int DAY_OF_WEEK

      See Also:
        Constant Field Values

    - #### YEAR

          protected static final int YEAR

      See Also:
        Constant Field Values

    - #### ALL_SPEC_INT

          protected static final int ALL_SPEC_INT

      See Also:
        Constant Field Values

    - #### NO_SPEC_INT

          protected static final int NO_SPEC_INT

      See Also:
        Constant Field Values

    - #### ALL_SPEC

          protected static final Integer ALL_SPEC

    - #### NO_SPEC

          protected static final Integer NO_SPEC

    - #### monthMap

          protected static final Map monthMap

    - #### dayMap

          protected static final Map dayMap

    - #### seconds

          protected transient TreeSet<Integer> seconds

    - #### minutes

          protected transient TreeSet<Integer> minutes

    - #### hours

          protected transient TreeSet<Integer> hours

    - #### daysOfMonth

          protected transient TreeSet<Integer> daysOfMonth

    - #### months

          protected transient TreeSet<Integer> months

    - #### daysOfWeek

          protected transient TreeSet<Integer> daysOfWeek

    - #### years

          protected transient TreeSet<Integer> years

    - #### lastdayOfWeek

          protected transient boolean lastdayOfWeek

    - #### nthdayOfWeek

          protected transient int nthdayOfWeek

    - #### lastdayOfMonth

          protected transient boolean lastdayOfMonth

    - #### nearestWeekday

          protected transient boolean nearestWeekday

    - #### lastdayOffset

          protected transient int lastdayOffset

    - #### expressionParsed

          protected transient boolean expressionParsed

    - #### MAX_YEAR

          public static final int MAX_YEAR

  - ### Constructor Detail

    - #### CronExpression

          public CronExpression(String cronExpression)
                         throws ParseException

      Constructs a new `CronExpression` based on the specified parameter.
      Parameters:
        `cronExpression` - String representation of the cron expression the new object should represent
      Throws:
        `ParseException` - if the string expression cannot be parsed into a valid `CronExpression`

  - ### Method Detail

    - #### isSatisfiedBy

          public boolean isSatisfiedBy(Date date)

      Indicates whether the given date satisfies the cron expression. Note that milliseconds are ignored, so two Dates falling on different milliseconds of the same second will always have the same result here.
      Parameters:
        `date` - the date to evaluate
      Returns:
        a boolean indicating whether the given date satisfies the cron expression

    - #### getNextValidTimeAfter

          public Date getNextValidTimeAfter(Date date)

      Returns the next date/time after the given date/time which satisfies the cron expression.
      Parameters:
        `date` - the date/time at which to begin the search for the next valid date/time
      Returns:
        the next valid date/time

    - #### getNextInvalidTimeAfter

          public Date getNextInvalidTimeAfter(Date date)

      Returns the next date/time after the given date/time which does not satisfy the expression
      Parameters:
        `date` - the date/time at which to begin the search for the next invalid date/time
      Returns:
        the next valid date/time

    - #### getTimeZone

          public TimeZone getTimeZone()

      Returns the time zone for which this `CronExpression` will be resolved.

    - #### setTimeZone

          public void setTimeZone(TimeZone timeZone)

      Sets the time zone for which this `CronExpression` will be resolved.

    - #### toString

          public String toString()

      Returns the string representation of the `CronExpression`
      Overrides:
        `toString` in class `Object`
      Returns:
        a string representation of the `CronExpression`

    - #### isValidExpression

          public static boolean isValidExpression(String cronExpression)

      Indicates whether the specified cron expression can be parsed into a valid cron expression
      Parameters:
        `cronExpression` - the expression to evaluate
      Returns:
        a boolean indicating whether the given expression is a valid cron expression

    - #### validateExpression

          public static void validateExpression(String cronExpression)
                                         throws ParseException

      Throws:
        `ParseException`

    - #### buildExpression

          protected void buildExpression(String expression)
                                  throws ParseException

      Throws:
        `ParseException`

    - #### storeExpressionVals

          protected int storeExpressionVals(int pos,
                                            String s,
                                            int type)
                                     throws ParseException

      Throws:
        `ParseException`

    - #### checkNext

          protected int checkNext(int pos,
                                  String s,
                                  int val,
                                  int type)
                           throws ParseException

      Throws:
        `ParseException`

    - #### getCronExpression

          public String getCronExpression()

    - #### skipWhiteSpace

          protected int skipWhiteSpace(int i,
                                       String s)

    - #### findNextWhiteSpace

          protected int findNextWhiteSpace(int i,
                                           String s)

    - #### addToSet

          protected void addToSet(int val,
                                  int end,
                                  int incr,
                                  int type)
                           throws ParseException

      Throws:
        `ParseException`

    - #### getSet

          protected TreeSet<Integer> getSet(int type)

    - #### getValue

          protected org.apache.tapestry5.ioc.internal.services.cron.ValueSet getValue(int v,
                                                                                      String s,
                                                                                      int i)

    - #### getNumericValue

          protected int getNumericValue(String s,
                                        int i)

    - #### getMonthNumber

          protected int getMonthNumber(String s)

    - #### getDayOfWeekNumber

          protected int getDayOfWeekNumber(String s)

    - #### getTimeAfter

          public Date getTimeAfter(Date afterTime)

    - #### setCalendarHour

          protected void setCalendarHour(Calendar cal,
                                         int hour)

      Advance the calendar to the particular hour paying particular attention to daylight saving problems.
      Parameters:
        `cal` -
        `hour` -

    - #### getTimeBefore

          public Date getTimeBefore(Date endTime)

      NOT YET IMPLEMENTED: Returns the time before the given time that the `CronExpression` matches.

    - #### getFinalFireTime

          public Date getFinalFireTime()

      NOT YET IMPLEMENTED: Returns the final time that the `CronExpression` will match.

    - #### isLeapYear

          protected boolean isLeapYear(int year)

    - #### getLastDayOfMonth

          protected int getLastDayOfMonth(int monthNum,
                                          int year)

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