If you need to use Java, installing the Java Runtime Environment (JRE) in OS X Mountain Lion is necessary even if you had Java previously installed in OS X Lion or Snow Leopard and just performed an upgrade to 10.8. That’s because Mountain Lion uninstalls Java during the upgrade process, this is to insure the newest version of the runtime is installed on the Mac for those who need it and leaving it out for those who don’t, theoretically preventing some potential security problems with Java like the old Flashback trojan.
Installing Java in OS X Mountain Lion is easy enough and can be done two ways:
- When a Java app is opened in Safari or elsewhere you will be prompted to install Java for OS X (2012-004 currently)
- Manual command line method to force the installation
The command line installation is fast and likely preferable for many advanced users since it can be initiated at any time, here’s what to do:
- Launch Terminal from /Applications/Utilities/ and type the following command:
- Hit return to see a message stating “No Java runtime present, requesting install” followed by a window prompting you to install Java SE in order to open “java”, click “Install” to get the latest version
Many Mac users won’t ever need to use Java and for the average person it may be best left uninstalled. Disabling java or leaving it uninstalled remains a decent security tip to protect a Macagainst some of the rare trojans and viruses floating around out there.