I’ve started encountering some weird exceptions trying to use the GWT designer. I’m on Ubuntu if it matters, GWT 2.4.0, Java 1.6.0_20 x64
When I use the designer, a previously used DisclosurePanel shows up in a pink box indicating. When viewing the details, it indicates a NoClassDefFound error. This makes no sense because in the code editor, the class is visible and compiles without error.
Secondly, I am unable to drop a CellTable instance on the designer. Even with the most basic T = java.lang.Object, the error comes back indicating an IllegalArgumentException : "Unable to find 'columns' in class com.google.gwt.user.client.UI.HTML.
This was working yesterday with the designer, but all of a sudden has entered the crapper. I tried reinstalling the GWT plugins, and even using a new eclipse install with fresh GWT plugins installed, but to no avail. Does anyone know the source of these errors and how to remedy them?
Alright, it seems that the other day I synced up my build machine for the fisrt time and had a different version of java installed on my dev machine. OpenJDK 1.6.0_20 (Iced Tea 1.9), vs Java SE 1.6.0_35.
Since this java was in my /usr/bin which was earlier in my PATH envi var than my 1.6.0_35 build that was at the end of the PATH, it was using hte older 0_20 version. I’m guessing the GWT designer was built with something closer to 1.6.0_35 than 1.6.0_20, and was causing conflicts as implied here.:
Start by checking your Eclipse “.log” file (found in your /.metadata directory). If the error references one of your classes or methods, check that your classpath properly references the class you are trying to use. Also check that your class is properly compiled (no red X’s) and that a .class file exists in your projects /bin directory. A mismatch between the JDK used to compile your code and the JVM used to run Eclipse can also manifest itself as a NoClassDefFoundError problem. For example, if you compile your code using JDK 1.5 or 1.6 and then run your Eclipse using a 1.4 or 1.5 JVM, you can have this problem. If the error refers to a custom widget, you should also check that your component does not trigger an exception during its initialization (which can manifest itself as a NoClassDefFoundError). Try refreshing and cleaning your project using the Project > Clean… or Project > Build Project commands. If that does not help, send a test case to support.