Saturday, February 12, 2011

Running WPF Designer with Java 6

Today I encountered a perplexing error in the portlet factory designer:

(com/ibm/workplace/wcm/api/Workspace) bad major version at offset=6
Cannot instantiate Class Name: com.dsixe.wcm.Content - java.lang.UnsupportedClassVersionError: (com/ibm/workplace/wcm/api/Workspace) bad major version at offset=6

Now I've seen this type of error before, all it requires is a tweak to the project properties, change the runtime to the appropriate version - in this case it seemed to be 6. But the error would not go away.

The source of the problem was a linked java object builder pointing to a class which contained a reference to a class requiring java 6. When a classname is defined in the builder, I assume it must attempt to introspect the class to determine its methods, and I guess it was unable to instantiate it. So the problem seemed to be that the designer (eclipse) needed to execute in java 6 environment.

Switching to JRE 6

Eclipse start parameters can be defined in a configuration file named C:\IBM\Portlet Factory\Eclipse\eclipse.ini. One of those parameters tells it which JDK to use, so I added the following to the top of the file

C:\Program Files (x86)\Java\jre6\bin

Then I restarted eclipse. Problem gone.

EDIT 02/05/2013:

Using IBM's J9 JRE
Developers using the publish to websphere portal feature in the WEF designer will need to run the J9 version of java. This can be downloaded from , ensure that you pick the 32 bit version and unzip (I put it in C:\IBM where WEF is installed). For some reason the install of WEF on windows uses 32 bit version of eclipse. Edit the eclipse.ini to use this:


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