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So, I broke Java I'm on Mountain Lion. I had Java 6 SE (the Apple-distributed JDK/JRE) and Oracle's Java 7u10 preview. Trying to get a stub app to launch with Java 7, I unchecked the Java 6 SE checkboxes in Java Now not only will my stub app not launch, but Java won't launch (it says there's no valid JRE 1.4+ available). I understand this is probably because Apple's Java launcher stub is not compatible with 7u10 -- not sure how to manually re-enable SE 6, though.

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I'm hoping you are running 10.6 and not a newer version of OS X since the java waters are quite muddy with Apple removing functionality and having a lot of downloads to confuse us all. – bmike Oct 26 '12 at 2:46
The accepted answer to How to reinstall Java 6 on Mac OS X Mountain Lion involves a sequence of commands. – Graham Perrin Nov 25 '12 at 18:07

Two things are needed worst case (and assuming you are still on 10.6 Snow Leopard):

  1. Re-download the SE 6 and install it
  2. Manually enable browser plug in if you care to have that functionality:
 ln -sf /System/Library/Java/Support/Deploy.bundle/Contents/Resources/JavaPlugin2_NPAPI.plugin "/Library/Internet Plug-Ins/JavaAppletPlugin.plugin"
 ln -sf /System/Library/Frameworks/JavaVM.framework/Commands/javaws /usr/bin/javaws

There is great coverage of the how and why I came up with these steps from Rich Trouton's blog:

Apple also has similar steps in their KB article about the move from SE 6 to 7 here:

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The link to Java for Mac OS X 10.6 Update 11 (Java 6 Update 37 for Snow Leopard) is no longer appropriate since the opening poster has confirmed his use of Mountain Lion. For OS X Lion v10.7 or later, for the same version of Java: Java for OS X 2012-006. – Graham Perrin Nov 3 '12 at 18:33 and refer to Apple article HT5559, modified 2012-10-22:

Java for OS X 2012-006: How to re-enable the Apple-provided Java SE 6 applet plug-in and Web Start functionality

to disable Java 7 and re-enable the Apple-provided Java SE 6 plug-in

  • three commands
  • a fourth command to re-enable Apple's Java SE 6 Web Start.
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