* lisp/ob-java.el: Add support for variables and return values. Write
tempfiles to the `org-babel-temporary-directory'. Make package,
class, and main method definitions optional.
* testing/lisp/test-ob-java.el: Add tests.
ob-java was missing features common to many other org-babel
implementations, such as the ability to accept variables and return a
value. This brings those features to ob-java, making the experience
more consistent across org-babel languages, and expanding the ways
java source blocks interact with org mode buffers.
A simple java program requires boilerplate code to declare a class and
main method. This boilerplate code makes java source blocks more
tedious to write and more effort to read. This is more evident in an
org buffer where there may be many small source blocks. This change
makes that code optional. If it is not provided, the source block
will be wrapped in the boilerplate code just before compilation.
Most org babel implementation write temporary files to the
`org-babel-temporary-directory'. That avoids polluting the current
directory and provides built-in support for tramp. ob-java would
write source files and binaries to the directory containing the org
file by default. This may be unexpected and unwanted, and didn't work
with tramp. This change writes all tempfiles to the
`org-babel-temporary-directory'.
Executing an ob-java source block would always try to compile and run
the code in the source block, so a source block that wasn't
runnable (didn't contain a main method) would error during run. This
change adds a generic main method just before compilation if one isn't
included in the source block so that the run will succeed.
There were no tests for ob-java. This adds tests.
