Package org.jobrunr.scheduling.cron

Class CronExpression

java.lang.Object
org.jobrunr.scheduling.Schedule
org.jobrunr.scheduling.cron.CronExpression
All Implemented Interfaces:
Comparable<Schedule>
public class CronExpression extends Schedule
Schedule class represents a parsed crontab expression.

The schedule class cannot be instantiated using a constructor, a Schedule object can be obtain by using the static create(java.lang.String) method, which parses a crontab expression and creates a Schedule object.

Original version https://github.com/asahaf/javacron

  • Method Details

    • create

      public static CronExpression create(String expression)
      Parses crontab expression and create a Schedule object representing that expression.

      The expression string can be 5 fields expression for minutes resolution. 

        ┌───────────── minute (0 - 59)
  │ ┌───────────── hour (0 - 23)
  │ │ ┌───────────── day of the month (1 - 31) or L for last day of the month
  │ │ │ ┌───────────── month (1 - 12 or Jan/January - Dec/December)
  │ │ │ │ ┌───────────── day of the week (0 - 6 or Sun/Sunday - Sat/Saturday)
  │ │ │ │ │
  │ │ │ │ │
  │ │ │ │ │
 "* * * * *"

      or 6 fields expression for higher, seconds resolution. 

        ┌───────────── second (0 - 59)
  │ ┌───────────── minute (0 - 59)
  │ │ ┌───────────── hour (0 - 23)
  │ │ │ ┌───────────── day of the month (1 - 31) or L for last day of the month
  │ │ │ │ ┌───────────── month (1 - 12 or Jan/January - Dec/December)
  │ │ │ │ │ ┌───────────── day of the week (0 - 6 or Sun/Sunday - Sat/Saturday)
  │ │ │ │ │ │
  │ │ │ │ │ │
  │ │ │ │ │ │
 "* * * * * *"
      Parameters:
      expression - a crontab expression string used to create Schedule.
      Returns:
      Schedule object created based on the supplied crontab expression.
      Throws:
      InvalidCronExpressionException - if the provided crontab expression is invalid. The crontab expression is considered invalid if it is not properly formed, like empty string or contains less than 5 fields or more than 6 field. It's also invalid if the values in a field are beyond the allowed values range of that field. Non-occurring schedules like "0 0 30 2 *" is considered invalid too, as Feb never has 30 days and a schedule like this never occurs.

    • next

      public Instant next(Instant createdAtInstant, Instant currentInstant, ZoneId zoneId)
      Calculates the next occurrence based on provided base time.
      Specified by:
      next in class Schedule
      Parameters:
      createdAtInstant - Instant object based on which calculating the next occurrence.
      currentInstant - Instant object used to calculate next occurrence (normally Instant.now()).
      zoneId - the zone for which to calculate the schedule
      Returns:
      Instant of the next occurrence.

    • equals

      public boolean equals(Object obj)
      Compares this object against the specified object. The result is true if and only if the argument is not null and is a Schedule object that whose seconds, minutes, hours, days, months, and days of weeks sets are equal to those of this schedule.

      The expression string used to create the schedule is not considered, as two different expressions may produce same schedules.

      Overrides:
      equals in class Schedule
      Parameters:
      obj - the object to compare with
      Returns:
      true if the objects are the same; false otherwise

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Schedule

    • isLeapYear

      public static boolean isLeapYear(int year)

    • getNumberOfFields

      public int getNumberOfFields()

    • getExpression

      public String getExpression()

    • validateSchedule

      public void validateSchedule()
      Specified by:
      validateSchedule in class Schedule

    • toString

      public String toString()
      Overrides:
      toString in class Object