Java dependencies are difficult for an external dependency-based
construction tool to accomodate. Determining Java class dependencies
is more complicated than the simple pattern-matching of C or C++
#include files. From the point of view of an
external build tool, the Java compiler behaves "unpredictably"
because it may create or update multiple output class files and
directories as a result of its internal class dependencies.
An obvious SCons implementation would be to have the
object parse output from Java -depend -verbose to
calculate dependencies, but this has the distinct disadvantage of
requiring two separate compiler invocations, thereby slowing down