Close the Java Control Panel and launch Safari.

In the “Security” tab of the Java Control Panel, make sure the “Enable Java content in browser” checkbox is checked, and lower the security to “Medium.”.

Open the Mac System Preferences and select “Java” (found in the “Other” section).

Select that and “Disable Local File Restrictions.” You should see a new “Develop” menu bar item in Safari.

Check the “Show Develop menu in menu bar” checkbox:.

Open up Safari’s Preferences and navigate to the “Advanced” panel.The following instructions are for Safari (version 6.0.4). So you’ll need to use another browser like Safari or Firefox. Java 7 requires a 64 bit browser, and Chrome, at the time I’m writing this entry, is 32 bits.This isn’t just good advice… you may find that older versions of the Java plug-in won’t run anymore. The latest version includes fixes for previous security issues. Make sure you are using the latest JRE available for the Mac.Personally, I lower the security to test my own code and then immediately reset the security levels back to a higher level when I’m finished. If you decide to lower the security settings, you do so at your own risk. WARNING: these security settings were enabled for a reason: to help avoid running malware on your system.

Of course, we’re seeing fewer and fewer new applets being made these days, but for those that are still supporting them, and want to do local testing on a Mac (OS X 10.7.3 Lion or greater), security restrictions will need to be lowered via the following steps: In many cases you won’t see any warnings, errors, or further instructions the applet will simply not appear in the web page.

With recent security issues involving the JRE, Apple has added a few layers of protection to prevent local Java Applets from running in a browser.

Chrome applet viewer