I'm trying to build a theme with GXT 4.1. When I try to run the themebuilder on the vanilla neptune.theme I get this error:
% ../themebuilder/bin/themer.sh neptune.theme
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.codehaus.groovy.reflection.CachedClass$3$1 (file:/home/jorge/tmp/theme-4.1/themebuilder/bin/gxt-themebuilder.jar) to method java.lang.Object.finalize()
WARNING: Please consider reporting this to the maintainers of org.codehaus.groovy.reflection.CachedClass$3$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
template generation started
error with template generation
groovy.lang.MissingPropertyException: No such property: URLs for class: jdk.internal.loader.ClassLoaders$AppClassLoader
This seems to be a problem with java 9+ where the application class loader is no longer an instance of java.net.URLClassLoader. I tried using java 8 but it is not compatible with themebuilder.
The error when used with java 8 is this:
Exception in thread "main" java.lang.UnsupportedClassVersionError: com/sencha/gxt/themebuilder/config/shared/CfgObject has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0
You're right. For the GXT ThemeBuilder, there are several instances where it has to copy files from the themebuilder jar (such as images, or the theme template java files). This used the URLClassLoader.
It should work with Java 8. If you can update your question to describe your java 8 errors, I can address that.
Edit - From your updated question, I realize that GXT 4.1 was built using Java 11 (class file version 55.0). I confirmed this from the Idera/Sencha release notes: https://docs.sencha.com/gxt/4.x/guides/announcements/release_notes.html
It's noted as a "Known Issue" that "Users may be required to update other libraries to work with Java 11 & GWT 2.9.0".
I'd suggest running the themer with JDK 11. Alternatively, there's some documentation on using an archetype for generating a theme using maven. https://docs.sencha.com/gxt/4.x/guides/getting_started/maven/Archetypes.html