I don't have experience with JBoss. However, I would ask the question, "Why do you need a container?" It increases complexity. Unless you have a demonstrated need, they can waste a lot of time for little payback.
Regarding the dread Null Pointer Exception, which I seem to be exceptionally good at generating, here is what I have collected thus far:
1. The logs give really good clues as to where the null pointer exception happened, while at the same time offering little concrete debug information that would help you determine the error and fix it. Get them working, then read them. Make sure your source code has the right end of line sequences for your platform so that the line numbers in the error messages correspond to the line numbers you see in your editor (thanks, Henner!). Figure out if the error is on initialization, at form compile time or at form runtime.
2. There are two common places that Null Pointer exceptions occur: (a) at webapp initialization time if you have a problem with your dbforms-config.xml or if you have not set up your connection description properly, or (b) if you refer to a column that is either not defined, is defined improperly or is a query column that is not fully qualified with exactly the same alias with which the column is specified in the query text itself. This code will compile perfectly and crash with Null Pointer Exception at runtime.
3. In general, other errors and indiscretions committed in tag syntax is reported as some kind of readable error message that refers to the JSP, not as a NULL pointer exception.
To expand on my second point, the SetTableName bad guy is usually dbforms-config.xml . I screwed mine up by using an "eval" column type, which is non-ansi and not supported by dbforms. If any table or query section in dbforms-config.xml throws an error, the dbforms-config.xml file parser bombs out before the end. This means that your connection never gets read in, no connection means no tables so the end result is a single error in dbforms-config.xml renders your entire webapp catatonic. What would be worse than this would be to put the connection information first, which would result in a partially working webapp that may fool you into thinking it is OK. Best to leave everything as it is!
Bill
Earlier today Theo Prinsloo wrote:
Hi I saw the troubleshooting question you asked about the error you got -> java.lang.NullPointerException
at org.dbforms.taglib.DbFormTag.setTableName(DbFormTag.java:299)
I am currently struggling with the same problem after I transfered my projects from Tomcat onto JBoss.Did you find a solution for the problem or do you have any advice for me. I would appreciate any assistance.
Thank You, Theo Prinsloo
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