How to convert CRON string to ScheduleExpression in Java?

Question

I got this problem:

I have a text field,

There should be a CRON expression written, and later on saved.

Now I need a method to convert the CRON string (

Answer 1

I found the answer, but forgot to answer it, here is the code that worked for me:

private ScheduleExpression parseCronExpressionToScheduleExpression(String cronExpression) {

    if ("never".equals(cronExpression)) {
        return null;
    }

    // parsing it more or less like cron does, at least supporting same fields (+ seconds)

    final String[] parts = cronExpression.split(" ");
    final ScheduleExpression scheduleExpression;

    if (parts.length != 6 && parts.length != 5) {
        scheduleExpression = scheduleAliases.get(cronExpression);
        if (scheduleExpression == null) {
            throw new IllegalArgumentException(cronExpression + " doesn't have 5 or 6 segments as excepted");
        }
        return scheduleExpression;
    } else if (parts.length == 6) { // enriched cron with seconds
        return new ScheduleExpression()
                .second(parts[0])
                .minute(parts[1])
                .hour(parts[2])
                .dayOfMonth(parts[3])
                .month(parts[4])
                .dayOfWeek(parts[5]);
    }

    // cron
    return new ScheduleExpression()
            .minute(parts[0])
            .hour(parts[1])
            .dayOfMonth(parts[2])
            .month(parts[3])
            .dayOfWeek(parts[4]);
}

So, if you send the cron expression to the function, it will make a shedule expression out of it, but it does not work 100% on all cron expressions but on most

Here is what worked for the individual positions in the cron expression

*    works 
-    works
,    works
/    works
last works (only in the part Day Of Month)

What does not work are the letters, such as L, and the others, at least not when I last checked.

Hope this will help the next guy :)