I receive the following warning:
[javac] build.xml:9: warning: \'includeantruntime\' was not set,
defaulting to build.sysclasspath=last; set to false for re
As @Daniel Kutik mentioned, presetdef is a good option. Especially if one is working on a project with many build.xml files which one cannot, or prefers not to, edit (e.g., those from third-parties.)
To use presetdef, add these lines in your top-level build.xml file:
Now all subsequent javac tasks will essentially inherit includeantruntime="false". If your projects do actually need ant runtime libraries, you can either add them explicitly to your build files OR set includeantruntime="true". The latter will also get rid of warnings.
Subsequent javac tasks can still explicitly change this if desired, for example:
I'd recommend against using ANT_OPTS. It works, but it defeats the purpose of the warning. The warning tells one that one's build might behave differently on another system. Using ANT_OPTS makes this even more likely because now every system needs to use ANT_OPTS in the same way. Also, ANT_OPTS will apply globally, suppressing warnings willy-nilly in all your projects