I recently \"upgraded\" from OSX Mountain Lion to Yosemite and from R 3.1.3 to 3.2. Immediately after the upgrade, when I opened R or RStudio I got a pop-up message saying t
Run the following on the command line: sudo R CMD javareconf
Several solutions above have mentioned this, but they also suggest that one remove and subsequently re-install the rJava package. I found those additional steps to be unnecessary.