Getting various R packages to work with Java 1.8 and rJava on OSX

If you attempt to install various R packages (e.g. RWeka) on OSX using a Java 1.8 runtime, you're likely to run into the following error message (even though you have a perfectly good installation of Java):

"No Java runtime present, requesting install.
ERROR: loading failed"

There are a ton of threads out there about this problem, but it seems to boil down to this unclosed (and untouched since 2014-01) JDK issue -> https://bugs.openjdk.java.net/browse/JDK-7131356

The "solution" can be found on the last comment on this rJava github issue: https://github.com/s-u/rJava/issues/37

1. install JDK 1.6 from Apple (http://support.apple.com/kb/DL1572)
2. open a new terminal window and make sure you're still using 1.8 - "java -version"
3. run "sudo R CMD javareconf -n" from a terminal window
4. start up R and install rJava again from source - install.packages("rJava", type="source")