Comment 4 for bug 254587

I assume you have folder /usr/lib/jvm/java-6-sun present on your system but package sun-java6-jdk is not installed. Problem is in netbeans postinstall step which has test for presence jdk but it is not specific enough. We will fix it in next release. As workaround you can use --jdkhome on command line or fix netbeans_jdkhome property in /etc/netbeans/conf.