JDeveloper has trouble to locate the Java JDK.
To solve this problem run the following shell script in the terminal.
sudo mkdir /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6
sudo mkdir /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/bin
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/bin/java /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/bin/java
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/bin/javac /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/bin/javac
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/bin/javap /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/bin/javap
sudo ln -s /System/Library/Java/Support/Deploy.bundle/Contents/Home/bin/javaws /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/bin/javaws
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/bin/jar /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/bin/jar
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/bin/xjc /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/bin/xjc
sudo mkdir /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/lib
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Classes/classes.jar /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/lib/tools.jar
sudo mkdir /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/jre
sudo mkdir /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/jre/bin
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/bin/java /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/jre/bin/java
sudo mkdir /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/jre/lib
sudo ln -s /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Classes/classes.jar /System/Library/Java/Javavirtualmachines/1.6.0.jdk/Contents/Home/jdk6/jre/lib/rt.jar
