java.util.calendar help

[quantzie]

Hi everyone! I'm a beginner at coding and I've been trying out iReports. I would like to get an output of a date that will be 1 year before today each time I run the reports. I'm using PostgreSQL with iReport 3.7.4. I've the latest java version and I still can't find the class java.util.calendar inside iReports. The only ones that I can see are java.util.dates and java.sql.timestamp. How do I import in the java.util.calendar because I have searched around the internet and I can find examples of people using it. Thanks!

[cbarlow3]

I think you can get what you need out of java.util.date.  Define a variable called $V{OneYearAgo} as type java.util.Date, and set the Evaluation expression to    

new Date()-365

(or, to be more precise, define $V{Today} as new Date() and then $V{OneYearAgo} as:

new Date($V{Today}.getAt(Calendar.YEAR)-1900-1,$V{Today}.getMonth(),$V{Today}.getDate())

Dates have all kinds of pitfalls...in my case, I'm using Groovy, and I show that the getAt(Calendar.YEAR) pulls a four digit year, but that the Date() constructor expects number of years since 1900.  And I show that getMonth results in a month from 0 to 11, not 1 through 12, but luckily it is actually the same interpretation of month that the Date() constructor uses at least!

[cbarlow3]

I almost forgot to mention: I think this will work fine when you run it interactively.  If you go to schedule it, I think I've read on this forum that the date (and everything else) will be interpreted at the time you schedule, not at the time it actually runs, so be aware of that limitation.

[quantzie]

Thanks for the reply! I've been trying to find a way to calculate the dates in that direction but I couldn't think of a way to do it.

Also, I think you are talking about the evaluation time? I've read up on it. Thanks!

[federico.cattozzi]

I didn't think that Groovy was so powerful! 

I use Joda, a Java framework for dates.

 If i have to filter rows by a date I use a parameters as DATE_FROM.

The default value for DATE_FROM can be:

new org.joda.time.DateMidnight().minusDays(365).toDate()

or

new org.joda.time.DateMidnight().minusYears(1).toDate()

Joda is very useful to work with dates on a single line of code.

You can add Joda's jar to iReport or Tomcat/JasperServer classpath.