Question

I have to use java.util.Calendar in GWT entry point, but I got error while running the application, that is because GWT is not able to find source code, is there anyway I could fix this issue.

Thanks in advance!!!

Answer 1

java.util.Calendar is not an emulated class. You can find a list of emulated classes here:

http://code.google.com/webtoolkit/doc/latest/RefJreEmulation.html

I would strongly advise not to use any date/calendar library on the client side. You will probably only get yourself into trouble. In fact, even though java.sql.Date and java.util.Date are emulated in GWT, I would not use these either. If you’re looking to use Calendar, then chances are you want to support timezones on the client. Using the emulated Date classes, you will somehow have to convert the client’s Date from the browser’s timezone to some target timezone (GMT or whatever the user defined in user preferences?). This will most definitely be error prone. Using GWT’s TimeZone adds other issues. For instance, how do you map between java TimeZones and GWT TimeZones?

I recommend doing all date manipulation AND formatting on the server. On the client, you can simply use a date/month/year triplet. The server can have an association between user (or organization) and java.util.TimeZone (or joda timezone). Using the triplet and timezone you can easily create the specific instance in time.