0/1 means start at hour 0 and repeat each 1 hour
1/1 is start first day of the month and execute each 1 day
So this pattern executes the cron once each hour, starting day one of month and repeating itself every day.
there is a requirement to use
?in one ofdayOfWeekordayOfMonth:
Support for specifying both a day-of-week and a day-of-month value is not complete (you must currently use the ‘?’ character in one of these fields). – xenteros 7 mins ago
Then, 0 0 * * * ? * (and not 0 0 * * * *, with ? mandatory as you commented) will be same expression, ignoring seconds and minutes and taking each value of other elements, will execute each hour and everyday.
According your information:
0 0 0/1 1/1 * ? *
| | | | | | |
| | | | | | +-- Year (range: 1970-2099)
| | | | | +---- Day of the Week (range: 1-7 or SUN-SAT)
| | | | +------ Month of the Year (range: 0-11 or JAN-DEC)
| | | +--------- Day of the Month (range: 1-31)
| | +------------- Hour (range: 0-23)
| +---------------- Minute (range: 0-59)
+------------------ Second (range: 0-59)
And this explanation of the special characters:
* (“all values”)
used to select all values within a field. For example, “” in the minute field means *“every minute”.
? (“no specific value”)
useful when you need to specify something in one of the two fields in which the character is allowed, but not the other. For example, if I want my trigger to fire on a particular day of the month (say, the 10th), but don’t care what day of the week that happens to be, I would put “10” in the day-of-month field, and “?” in the day-of-week field.
/
used to specify increments. For example, “0/15” in the seconds field means “the seconds 0, 15, 30, and 45”. And “5/15” in the seconds field means “the seconds 5, 20, 35, and 50”. You can also specify ‘/’ after the ‘’ character – in this case ‘’ is equivalent to having ‘0’ before the ‘/’. ‘1/3’ in the day-of-month field means “fire every 3 days starting on the first day of the month”.
differences between * and ?
To explain difference between ? and * in the expressions, first of all take a look at this table:
Field Name Mandatory Allowed Values Allowed Special Characters
Seconds YES 0-59 , - * /
Minutes YES 0-59 , - * /
Hours YES 0-23 , - * /
Day of month YES 1-31 , - * ? / L W //allowed '?'
Month YES 1-12 or JAN-DEC , - * /
Day of week YES 1-7 or SUN-SAT , - * ? / L # //allowed '?'
Year NO empty, 1970-2099 , - * /
As you can see ? is only allowed in Day of month and Day of week is mandatory in one of both fields and will tell Quartz this value has not been defined, thus, use the other field (if you put ? into Day of month, the value used will be Day of week).