JSF convertDateTime renders the previous day

Solution 1:

This is undoubtedly a timezone-related issue.

JSF defaults to GMT (UTC) in date/time conversion. So if your server platform default timezone is GMT+X (not GMT-X), then the time will go back in the past X-amount of hours. If the time is already 00:00:00 (midnight), then the date will even go back one day in the past.

There are 2 standard ways to achieve your functional requirement anyway:

1. Tell JSF to use the server platform default timezone instead for all date/time conversion by adding the following context parameter to web.xml:

   <context-param>
       <param-name>javax.faces.DATETIMECONVERTER_DEFAULT_TIMEZONE_IS_SYSTEM_TIMEZONE</param-name>
       <param-value>true</param-value>
   </context-param>
   

2. Alter every <f:convertDateTime> to explicitly specify the webapp-specific timezone. As you're based in Germany and the date format pattern also confirms this, I'll assume CET.

   <f:convertDateTime ... timeZone="CET" />
   

In any case, using a non-universal or even mixed timezone throughout the application is not recommendable. It's recommend to set the timezone in all layers and environments to UTC. Not only in the server and front end tier and presentation layer, but also in the SQL database and back end tier and persistence layer. This way the code is not sensitive to timezone and DST(!) related matters and you can just focus on altering the timezone during presentation only, if necessary.

See also:

• Daylight saving time and time zone best practices