org.springframework.scheduling.support

Class CronExpression

java.lang.Object

org.springframework.scheduling.support.CronExpression

public final class CronExpression
extends Object

Representation of a crontab expression that can calculate the next time it matches.

CronExpression instances are created through parse(String); the next match is determined with next(Temporal).

Since:

5.3

Author:

Arjen Poutsma

See Also:

CronTrigger

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
int	hashCode()
static boolean	isValidExpression(String expression) Determine whether the given string represents a valid cron expression.
<T extends Temporal & Comparable<? super T>> T	next(T temporal) Calculate the next Temporal that matches this expression.
static CronExpression	parse(String expression) Parse the given crontab expression string into a CronExpression.
String	toString() Return the expression string used to create this CronExpression.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

parse

public static CronExpression parse(String expression)

Parse the given crontab expression string into a CronExpression. The string has six single space-separated time and date fields:

 ┌───────────── second (0-59)
 │ ┌───────────── minute (0 - 59)
 │ │ ┌───────────── hour (0 - 23)
 │ │ │ ┌───────────── day of the month (1 - 31)
 │ │ │ │ ┌───────────── month (1 - 12) (or JAN-DEC)
 │ │ │ │ │ ┌───────────── day of the week (0 - 7)
 │ │ │ │ │ │          (0 or 7 is Sunday, or MON-SUN)
 │ │ │ │ │ │
 * * * * * *
 

The following rules apply:

• A field may be an asterisk (*), which always stands for "first-last". For the "day of the month" or "day of the week" fields, a question mark (?) may be used instead of an asterisk.
• Ranges of numbers are expressed by two numbers separated with a hyphen (-). The specified range is inclusive.
• Following a range (or *) with /n specifies the interval of the number's value through the range.
• English names can also be used for the "month" and "day of week" fields. Use the first three letters of the particular day or month (case does not matter).
• The "day of month" and "day of week" fields can contain a L-character, which stands for "last", and has a different meaning in each field:
  • In the "day of month" field, L stands for "the last day of the month". If followed by an negative offset (i.e. L-n), it means "nth-to-last day of the month". If followed by W (i.e. LW), it means "the last weekday of the month".
  • In the "day of week" field, L stands for "the last day of the week". If prefixed by a number or three-letter name (i.e. dL or DDDL), it means "the last day of week d (or DDD) in the month".
• The "day of month" field can be nW, which stands for "the nearest weekday to day of the month n". If n falls on Saturday, this yields the Friday before it. If n falls on Sunday, this yields the Monday after, which also happens if n is 1 and falls on a Saturday (i.e. 1W stands for "the first weekday of the month").
• The "day of week" field can be d#n (or DDD#n), which stands for "the n-th day of week d (or DDD) in the month".

Example expressions:

• "0 0 * * * *" = the top of every hour of every day.
• "*/10 * * * * *" = every ten seconds.
• "0 0 8-10 * * *" = 8, 9 and 10 o'clock of every day.
• "0 0 6,19 * * *" = 6:00 AM and 7:00 PM every day.
• "0 0/30 8-10 * * *" = 8:00, 8:30, 9:00, 9:30, 10:00 and 10:30 every day.
• "0 0 9-17 * * MON-FRI" = on the hour nine-to-five weekdays
• "0 0 0 25 12 ?" = every Christmas Day at midnight
• "0 0 0 L * *" = last day of the month at midnight
• "0 0 0 L-3 * *" = third-to-last day of the month at midnight
• "0 0 0 1W * *" = first weekday of the month at midnight
• "0 0 0 LW * *" = last weekday of the month at midnight
• "0 0 0 * * 5L" = last Friday of the month at midnight
• "0 0 0 * * THUL" = last Thursday of the month at midnight
• "0 0 0 ? * 5#2" = the second Friday in the month at midnight
• "0 0 0 ? * MON#1" = the first Monday in the month at midnight

The following macros are also supported:

• "@yearly" (or "@annually") to run un once a year, i.e. "0 0 0 1 1 *",
• "@monthly" to run once a month, i.e. "0 0 0 1 * *",
• "@weekly" to run once a week, i.e. "0 0 0 * * 0",
• "@daily" (or "@midnight") to run once a day, i.e. "0 0 0 * * *",
• "@hourly" to run once an hour, i.e. "0 0 * * * *".

Parameters:

expression - the expression string to parse

Returns:

the parsed CronExpression object

Throws:

IllegalArgumentException - in the expression does not conform to the cron format

isValidExpression

public static boolean isValidExpression(@Nullable
                                        String expression)

Determine whether the given string represents a valid cron expression.

Parameters:

expression - the expression to evaluate

Returns:

true if the given expression is a valid cron expression

Since:

5.3.8

next

@Nullable
public <T extends Temporal & Comparable<? super T>> T next(T temporal)

Calculate the next Temporal that matches this expression.

Type Parameters:

T - the type of temporal

Parameters:

temporal - the seed value

Returns:

the next temporal that matches this expression, or null if no such temporal can be found

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

toString

public String toString()

Return the expression string used to create this CronExpression.

Overrides:

toString in class Object

Returns:

the expression string