NOTE: If you wish to move to Java SE 6 for Tiger or a pre-10.5 release of OS X, you may want to consider using SoyLatte, as recommended by the 2 tablespoons blog. I don’t imagine that any 3.x version of Eclipse would raise additional issues.

When you unpack the installer .dmg for Eclipse 3.4 Ganymede, it’s simply going to install the package. It will not automatically assume that you want to use it (not such a bad assumption, as it turns out). So there are a few caveats you need to deal with. I’m taking the approach of addressing all the details I know of, regardless of how obvious this may all seem :blush:

Post-install, Java 5 will still be in active use:

% ls -l /usr/bin/java
/usr/bin/java -> /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java
% Lunditer:~ root# java -version
java version "1.5.0_16"

You’ll see something much like this under /System/Library/Frameworks/JavaVM.framework/Versions:

1.3 -> 1.3.1
1.4 -> 1.4.2
1.4.1 -> 1.4
1.5 -> 1.5.0
Current -> A
CurrentJDK -> 1.5

Initially, I went and modified the symlink for CurrentJDK. Modifying the symlink for Current brought me nothing but pain. You can get the results you want by making the following change:

CurrentJDK -> 1.6.0

I’d had it set up that way until I wrote this post. But Apple highly discourages this practice. Instead, they recommend that you use the Java Preferences pane. Get rid of all your symlink shenanigans, and simply drag the ‘Java SE 6’ option to the top of the applet and application listings. It works like a charm. Start a new Terminal shell and you can confirm:

% /usr/bin/java -version
java version "1.6.0_07"
% /usr/bin/javac -version
javac 1.6.0_07

However … from my experience, this is a user-specific setting. Which means if you run Java as root, you’ll still get Java SE 1.5. Not a problem. We’ll stick with the Apple-sanctioned solution here.

Hooray, Java SE 6! Now let’s start Eclipse 3.4! Hooray … oops? Startup failure dialog:

JVM terminated.
Exit code=-1
-vm /System/Library/Frameworks/JavaVM.framework

This is a well documented issue. Both the Rob Kischuk and Stack Overflow blogs are very helpful in explaining that; Eclipse uses 32-bit SWT-Cocoa / Carbon, and Mac OS Java SE 6 only comes in a 64-bit flavor. I have not looked into the SoyLatte option, as suggested above, though that may prove to be an alternative approach.

I had some struggles getting their approach to work (until now, that is). Easiest way to start config testing is to run Eclipse from the command line:

% cd /Applications/eclipse/
% ./eclipse -vm /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Commands/java

You can also provide /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0, which I extrapolated from the -vm setting in the failure message. If you still get an error dialog, you may see multiple instances of -vm, but that’s a red herring; it will work once properly configured.

Great. Once that’s working for you, let’s apply it to the App shortcut. There’s two ways you can go about this:

The blogs above recommend that you modify the Info.plist:

  • edit /Applications/eclipse/
  • uncomment the following line:

Alternately, you can modify eclipse.ini, where you might also configure your JVM memory configuration:

  • edit /Applications/eclipse/
  • add the following line:
    -vm /System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Commands/java

Either dab will do ya. But if you didn’t know before, now you know where eclipse.ini lives :thumbsup:

Things should be grand now. If they aren’t, I suggest trying some variations while running Eclipse from the command line. It took me a while to get the right combination, even though this post and (the ones it references) may seem very cookie-cutter. It will eventually work for you!

Now, I mentioned that the Apple-sanctioned approach seems to be user-specific. And I run Tomcat as root. So you will probably still want to add the traditional environment settings.

You can either make these changes to /etc/profile, or to the ~/.bashrc of each relevant account. No surprises here:

export JAVA_HOME=/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home

My experiments to get /etc/paths to inject something into the path before ‘/usr/bin’ weren’t so useful, so I chose the brute force method.

If you’re going to use sudo to run Tomcat, you’ll want to make sure to load the bash environment.

% sudo su -

to guarantee that root’s environment includes the custom /etc/profile overrides. No dash, and it no work. Tomcat Java 5 + App Java 6 =

SEVERE: Error deploying web application directory ...
java.lang.UnsupportedClassVersionError: Bad version number in .class file

With the environment in place, you should be good to go.

The writing of this post drove me to (a) drop the symlinks, (b) use Java Preferences pane and (c) get the right -vm config set up (since I’d been leaning entirely on the environment settings up to this point). So there are definitely a few ways to skin this cat.