/Applications/Netbeans
folder, and open the Netbeans package.etc/netbeans.conf
# Default location of JDK, can be overridden by using --jdkhome [<dir>:#netbeans_jdkhome="/path/to/jdk"
netbeans_jdkhome="/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home/"
after theses lines.