Bug 61365

Me and according to Google a very large bunch of other people face the "large classpath problem": Having many jar files in the classpath breaks calls to javac and java. 

The solution currently advertised in many forums in to create a jar file that contains paths to the really used jars in its manifest and then to pass this jar file as the only classpath element. This solution is in my eyes far from optimal because it creates a new file on disk which is also ugly to create in the build.xml (add about 20 lines just to work around a problem that many users face, see https://stackoverflow.com/questions/31006815/relative-paths-for-classpath-in-build-xml-ant-build).

Solution 1: Add a relative="true" attribute to the <Classpath> element which works similar as the relative="true" in the <Property> element (Maybe also a basedir attribute). I don't know if it would be better to add these attributes to the <pathelement> or maybe both, because I don't know the implementaton details. I sometimes create my classpaths from pathelements, and sometimes from filesets (which should therefore also be optionally relative) so decide for yourself on a solution that covers all bases. 

A relative classpath should store all its elements in a relative way (vs. storing them as absolute paths and just converting them to relative during output). This might also help some users that use globbing to map a classpath to another directory.

Solution 2 (preferred): Also I wonder if it wouldn't be possible to automatically convert the Classpath to relative paths at the time java or javac are called! When these programs are forked ant already knows the work directory for these tools. It could therefore just strip the working directory from the classpath entries that point to jars below the working directory at least. This creates shorter command lines, looks much better in logfiles and is currently my preferred solution because then there is no need to change the docs or api.