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Build.xml and Java 1.5
When I run build.xml as an Ant build, I get a message saying that my Java is 1.6 and I need "genuine" Java 1.5. Besides this not being true (I have changed every place in Eclipse that says 1.6 to 1.5), why in the world would GWT need "genuine" 1.5? What's wrong with 1.6 (or 1.7 for that matter)? Where is the script getting the 1.6 version? How can I change it? My solution for now is to modify the ant script.
1.6 may be coming from the project facet, but it needs to be 1.6 or the Dynamic Web Module will not work. Is development on Vaadin 6.x supposed to be 1.6 or 1.5?
Not many people need to compile the whole Vaadin JAR from sources (often you can just copy a single class to your project and modify it if necessary), but if developing Vaadin core:
Vaadin 6 has and will retain Java 1.5 compatibility, while Vaadin 7 (since alpha 3) requires at least Java 1.6.
The support for 1.5 is there because there are still application server deployments around that do not support 1.6 and get upgraded slowly so we have made a policy decision to continue supporting it for the whole Vaadin 6 series. At least we don't get requests to support 1.4 anymore...
You can use the property "ignoreversion=1" to make the build script ignore the real version of JDK in use and accept JDK 1.6 or 1.7.