Just set java_home of 1.8 jdk version in netbeans.conf
file:
/Applications/NetBeans/NetBeans 8.2.app/Contents/Resources/NetBeans/etc/netbeans.conf
uncomment line:
netbeans_jdkhome="path/to/jdk"
and set path to your 1.8 jdk, in my case:
netbeans_jdkhome="/Library/Java/JavaVirtualMachines/jdk1.8.0_121.jdk/Contents/Home"
This approach lays you to have several jdk versions on mac os