Fixing Kindle Previewer on OS X Yosemite
Apple’s newest OS X release, Yosemite, seems to be breaking Kindle Previewer. Here’s how to fix it.
Download the Apple supported version of Java here: http://support.apple.com/kb/DL1572?viewlocale=en_US&locale=en_US
Install xQuartz from here: http://xquartz.macosforge.org/landing/
Once both of these applications are installed you should have no issues opening EPUBs and other file types in Kindle Previewer.