Joseph D. Darcy's Sun Weblog

Friday August 07, 2009

Annotation Processing Build Advice: Set source and class file destinations

In addition to following the general build advice of setting source, target, and encoding, when running annotation processors the source and class file destination directories should be set via javac's -s directory and -d directory options, respectively. Using the Filer, annotation processors can generate new source code to be compiled as part of the project and can also even generate new class files directly.

As recommended on the annotation processing forum, a much more hygienic build results when different kinds of generated output files are not intermixed with each other and any kind of output file is not mixed with any input files. (Input files would presumably be tracked under version control where generated files would not be.) In more detail:

• Set the directory for outputting generated source files using -s

• Set the directory for outputting generated class file code using -d

• Do not have the source and class file output locations overlap with each other and do not have either of them overlap with the sourcepath or classpath.

Following these guidelines clearly delineates inputs to the compiler and outputs from the compiler.

Although apt has been deprecated, the same recommendations hold there too.