I always encountered this error when I started learning Oracle ADF in JDeveloper and had found no straightforward answer in the forums. Now that I was able to find the solution through a similar case in Metalink, I thougth that it would help other beginners like me, if I will post the solution here.
Error: java.sql.SQLDataException: ORA-01882: timezone region not found
Error: java.lang.NumberFormatException: For input string: ""
Solution: add a java option "-Duser.timezone=GMT" without the quotes in the run configuration under project properties on every project in JDeveloper. It is also important to restart the Server after configuring such java option.
Tags: JDeveloper 11g R1 WebLogic