Cronsmith
Cronsmith is a powerful and versatile Java utility library designed for handling cron expressions in an intuitive, object-oriented manner. It offers a highly flexible and user-friendly API for generating, parsing, and scheduling cron-based tasks with ease.
Built for seamless integration, Cronsmith provides full support for both Spring and Quartz cron expressions, ensuring compatibility with widely used scheduling frameworks. Moreover, it extends traditional cron syntax by introducing advanced patterns—such as multiple numbers combined with 'L' (last) and 'W' (weekday)—which were previously unsupported, offering greater precision and flexibility in scheduling.
Features
1. Object-Oriented CronExpression Builder
Cronsmith allows developers to construct complex cron expressions in an intuitive, object-oriented manner. This approach enables easy customization and avoids the need for manual string construction.
Example:
@Test
public void test1() {
CronExpression cronExpression = new CronBuilder()
.everyMinute(5)
.second(5)
.andSecond(10)
.toSecond(30);
System.out.println(cronExpression.toString());
assertEquals("5,10-30 */5 * * * ?", cronExpression.toString());
}
@Test
public void test2() {
CronExpression cronExpression = new CronBuilder()
.everyMonth()
.lastWeekday()
.hour(10)
.minute(1)
.toMinute(15);
System.out.println(cronExpression.toString());
assertEquals("0 1-15 10 LW * ?", cronExpression.toString());
}
@Test
public void test3() {
CronExpression cronExpression = new CronBuilder()
.year(2025)
.toYear(2028)
.everyMonth(2)
.lastDay()
.hour(12);
System.out.println(cronExpression.toString());
assertEquals("0 0 12 L */2 ? 2025-2028", cronExpression.toString());
}
@Test
public void test4() {
CronExpression cronExpression = new CronBuilder()
.everyYear(2026, 4)
.everyMonth(5, 7, 1)
.day(10).andDay(15).andDay(20).andLastDay(2)
.everyHour(10, 15, 1)
.at(10, 0)
.andSecond(15).andSecond(30).andSecond(45);
System.out.println(cronExpression.toString());
assertEquals("0,15,30,45 10 10-15 10,15,20,L-2 MAY-JUL ? 2026/4",
cronExpression.toString());
}
@Test
public void testK() {
CronExpression cronExpression = new CronBuilder()
.year(2025).toYear(2030).andYear(2035).toEnd(2)
.everyMonth(2, 12, 2)
.dayOfWeek(2, DayOfWeek.TUESDAY)
.and(3, DayOfWeek.WEDNESDAY).andLastFri()
.hour(2).andHour(3).andHour(4).toHour(17, 2)
.minute(0).toMinute(12, 3).andMinute(15).toMinute(40, 2).andMinute(46)
.andMinute(48).andMinute(50)
.everySecond(5);
System.out.println(cronExpression.toString());
assertEquals("*/5 0-12/3,15-40/2,46,48,50 2,3,4-17/2 ? 2/2 TUE#2,WED#3,5L 2025-2030,2035/2",
cronExpression.toString());
}
2. Cron Expression String Parsing and Reverse Engineering to CronExpression
Cronsmith includes a powerful parser built with ANTLR, allowing you to parse an existing cron expression string and convert it back into a structured CronExpression object.
Example:
@Test
public void test1() {
String cron = "0 15 10 ? * MON-FRI";
CronExpression cronExpression = CRON.parse(cron);
System.out.println(cronExpression);
assertEquals(cron, cronExpression.toString());
}
@Test
public void test2() {
String cron = "0 10,20,30 9-17 L * ?";
CronExpression cronExpression = CRON.parse(cron);
System.out.println(cronExpression);
assertEquals(cron, cronExpression.toString());
}
@Test
public void test3() {
String cron = "1,3,5,7,9 3-30/3 12-16 ? * TUE#1";
CronExpression cronExpression = CRON.parse(cron);
System.out.println(cronExpression);
assertEquals(cron, cronExpression.toString());
}
@Test
public void test4() {
String cron = "5-30/7 0-12/3,15-45/2 2,3,4-17/2 ? JAN-JUL MON-THU/2 2025-2033";
CronExpression cronExpression = CRON.parse(cron);
System.out.println(cronExpression);
assertEquals(cron, cronExpression.toString());
}
Parse Tree:
cron
second
secondField
rangeWithStep
5
-
30
/
7
<missing SPACE>
minute
minuteField
rangeWithStep
0
-
12
/
3
,
minuteField
rangeWithStep
15
-
45
/
2
<missing SPACE>
hour
hourField
2
,
hourField
3
,
hourField
rangeWithStep
4
-
17
/
2
<missing SPACE>
dayOfMonth
dayOfMonthField
?
<missing SPACE>
month
monthField
monthRange
monthName
JAN
-
monthName
JUL
<missing SPACE>
dayOfWeek
dayOfWeekField
weekdayRangeWithStep
dayOfWeekName
MON
-
dayOfWeekName
THU
/
2
year
yearField
yearRange
2025
-
2030
<EOF>
Retrieve next date and times from CronExpression
public static void main(String[] args) {
String cron = "0 1,3,5-20 12-16 1,3,20,LW MAR-SEP ? 2026/1";
CronExpression cronExpression = CRON.parse(cron);
int N = 1000; // Retrieve 1000 items
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
cronExpression.consume(ldt -> {
System.out.println(ldt.format(dtf));
}, N);
}
// Console:
// 2026-03-01 12:01:00
// 2026-03-01 12:03:00
// 2026-03-01 12:05:00
// 2026-03-01 12:06:00
// 2026-03-01 12:07:00
// 2026-03-01 12:08:00
// 2026-03-01 12:09:00
// 2026-03-01 12:10:00
// 2026-03-01 12:11:00
// 2026-03-01 12:12:00
// 2026-03-01 12:13:00
// 2026-03-01 12:14:00
// 2026-03-01 12:15:00
// 2026-03-01 12:16:00
// 2026-03-01 12:17:00
// 2026-03-01 12:18:00
// 2026-03-01 12:19:00
// 2026-03-01 12:20:00
// 2026-03-01 13:01:00
// 2026-03-01 13:03:00
// 2026-03-01 13:05:00
// ...
3. Built-in Scheduler
Cronsmith provides a built-in scheduler that allows you to execute tasks at specified intervals based on cron expressions. This feature makes it easy to schedule repetitive tasks efficiently.
Example: Scheduling a Task Every 5 Seconds
private ScheduledExecutorService scheduledExecutorService;
@Before
public void start() {
scheduledExecutorService =
Executors.newScheduledThreadPool(Runtime.getRuntime().availableProcessors() * 2);
}
@Test
public void testSchedulerAndRunTenTimes() {
int N = 10; // Run 10 times
final CountDownLatch latch = new CountDownLatch(N);
final AtomicInteger counter = new AtomicInteger();
CronFuture future = new CronBuilder()
.everySecond(5)
.scheduler(scheduledExecutorService)
.setDebuged(false)
.runTask(() -> {
System.out.println("Run task_" + counter.incrementAndGet());
latch.countDown();
}, N);
try {
latch.await();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
future.cancel(true);
assertTrue(future.isDone() && counter.get() == N);
}
@After
public void release() {
scheduledExecutorService.shutdown();
}
4. Advanced Part
Can specify day of year
public static void main(String[] args) {
int N = 1000;
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
new CronBuilder().setZoneId(ZoneId.of("UTC")).year(2025).day(208).andDay(330).toLastDay()
.at(12, 0).consume(ldt -> {
System.out.println(ldt.format(dtf));
}, N);
}
// Console:
// 2025-07-27 12:00:00
// 2025-11-26 12:00:00
// 2025-11-27 12:00:00
// 2025-11-28 12:00:00
// 2025-11-29 12:00:00
// 2025-11-30 12:00:00
// 2025-12-01 12:00:00
// 2025-12-02 12:00:00
// 2025-12-03 12:00:00
// 2025-12-04 12:00:00
// 2025-12-05 12:00:00
// 2025-12-06 12:00:00
// ...
Can specify week of year
public static void main(String[] args) {
int N = 1000;
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
new CronBuilder().setZoneId(ZoneId.of("UTC")).everyYear().week(40).andWeek(45).Mon().toFri()
.at(12, 0).consume(ldt -> {
System.out.println(ldt.format(dtf));
}, N);
}
// Console:
// 2025-09-29 12:00:00
// 2025-09-30 12:00:00
// 2025-10-01 12:00:00
// 2025-10-02 12:00:00
// 2025-10-03 12:00:00
// 2025-11-03 12:00:00
// 2025-11-04 12:00:00
// 2025-11-05 12:00:00
// 2025-11-06 12:00:00
// 2025-11-07 12:00:00
// 2026-09-28 12:00:00
// 2026-09-29 12:00:00
// 2026-09-30 12:00:00
// 2026-10-01 12:00:00
// 2026-10-02 12:00:00
// ...
Installation
Support Jdk1.8 or later
To use Cronsmith in your Java project, add the following dependency to your pom.xml (if using Maven):
<dependency>
<groupId>com.github.paganini2008</groupId>
<artifactId>cronsmith</artifactId>
<version>1.0.0</version>
</dependency>
If using Gradle:
dependencies {
implementation 'com.github.paganini2008:cronsmith:1.0.0'
}
Getting Started
- Add Cronsmith as a dependency in your project.
- Use
CronBuilderto create complex cron expressions. - Parse existing cron expressions using
CRON.parse(). - Schedule tasks using the built-in scheduler.
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