Class CronExpression

java.lang.Object
io.fluxzero.sdk.scheduling.CronExpression
public class CronExpression extends Object
This provides cron support for java8 using java-time.

Parser for unix-like cron expressions: Cron expressions allow specifying combinations of criteria for time such as: "Each Monday-Friday at 08:00" or "Every last friday of the month at 01:30"

A cron expressions consists of 5 or 6 mandatory fields (seconds may be omitted) separated by space.
These are:

Cron expression values
Field   Allowable values   Special Characters
Seconds (may be omitted)   0-59   , - * /
Minutes   0-59   , - * /
Hours   0-23   , - * /
Day of month   1-31   , - * ? / L W
Month   1-12 or JAN-DEC (note: english abbreviations)   , - * /
Day of week   1-7 or MON-SUN (note: english abbreviations)   , - * ? / L #

'*' Can be used in all fields and means 'for all values'. E.g. "*" in minutes, means 'for all minutes'

'?' Can be used in Day-of-month and Day-of-week fields. Used to signify 'no special value'. It is used when one want to specify something for one of those two fields, but not the other.

'-' Used to specify a time interval. E.g. "10-12" in Hours field means 'for hours 10, 11 and 12'

',' Used to specify multiple values for a field. E.g. "MON,WED,FRI" in Day-of-week field means "for monday, wednesday and friday"

'/' Used to specify increments. E.g. "0/15" in Seconds field means "for seconds 0, 15, 30, ad 45". And "5/15" in seconds field means "for seconds 5, 20, 35, and 50". If '*' s specified before '/' it is the same as saying it starts at 0. For every field there's a list of values that can be turned on or off. For Seconds and Minutes these range from 0-59. For Hours from 0 to 23, For Day-of-month it's 1 to 31, For Months 1 to 12. "/" character helsp turn some of these values back on. Thus "7/6" in Months field specify just Month 7. It doesn't turn on every 6 month following, since cron fields never roll over

'L' Can be used on Day-of-month and Day-of-week fields. It signifies last day of the set of allowed values. In Day-of-month field it's the last day of the month (e.g.. 31 jan, 28 feb (29 in leap years), 31 march, etc.). In Day-of-week field it's Sunday. If there's a prefix, this will be subtracted (5L in Day-of-month means 5 days before last day of Month: 26 jan, 23 feb, etc.)

'W' Can be specified in Day-of-Month field. It specifies closest weekday (monday-friday). Holidays are not accounted for. "15W" in Day-of-Month field means 'closest weekday to 15 i in given month'. If the 15th is a Saturday, it gives Friday. If 15th is a Sunday, the it gives following Monday.

'#' Can be used in Day-of-Week field. For example: "5#3" means 'third friday in month' (day 5 = friday, #3 - the third). If the day does not exist (e.g. "5#5" - 5th friday of month) and there aren't 5 fridays in the month, then it won't match until the next month with 5 fridays.

Case-sensitive No fields are case-sensitive

Dependencies between fields Fields are always evaluated independently, but the expression doesn't match until the constraints of each field are met. Overlap of intervals are not allowed. That is: for Day-of-week field "FRI-MON" is invalid,but "FRI-SUN,MON" is valid

Adopted from https://github.com/frode-carlsen/cron.

  • Method Details

    • parseCronExpression

      public static CronExpression parseCronExpression(String expression)
      Parses and caches a five-field cron expression without an explicit seconds field; invalid expressions cause IllegalArgumentException.

    • parseCronExpression

      public static CronExpression parseCronExpression(String expression, boolean withSeconds)
      Parses and caches a cron expression, including a leading seconds field when withSeconds is true; invalid expressions cause IllegalArgumentException.

    • nextTimeAfter

      public ZonedDateTime nextTimeAfter(ZonedDateTime afterTime)
      Returns the first matching time strictly after the supplied instant, searching at most four years ahead. Throws IllegalArgumentException if no match is found within that limit.

    • nextLocalDateTimeAfter

      public LocalDateTime nextLocalDateTimeAfter(LocalDateTime dateTime)
      Returns the next matching local date-time using the system default time zone and a four-year search limit.

    • nextTimeAfter

      public ZonedDateTime nextTimeAfter(ZonedDateTime afterTime, long durationInMillis)
      Returns the next matching time strictly after afterTime, bounded by the supplied duration in milliseconds; throws IllegalArgumentException if no match is found within the limit.

    • nextTimeAfter

      public ZonedDateTime nextTimeAfter(ZonedDateTime afterTime, ZonedDateTime dateTimeBarrier)
      Returns the first matching time strictly after afterTime and no later than dateTimeBarrier. Throws IllegalArgumentException when the search passes the barrier.

    • toString

      public String toString()
      Overrides:
      toString in class Object