Some time ago I had set JAVA_HOME in my .profile on Mac OS X to the following:
JAVA_HOME=/Library/Java/Home; export JAVA_HOME
To some extent this works, but it doesn’t apparently pick up your preferred JDK version that you can set via the Java Preferences app in /Applications/Utilities (you set your preferred version by dragging your choice to the top of the list).
To set JAVA_HOME to be set to your preferred version, use this instead:
JAVA_HOME=`/usr/libexec/java_home`; export JAVA_HOME
This post here talks about the first approach, but there’s a comment in response to the post that points out the second point.