Java install/update issue

[munit]

I have been looking at various things to do now I have Kali installed on my laptop and found this link: http://www.blackmoreops.com/2014/03/03/20-things-installing-kali-linux/

update-alternatives --install /usr/bin/java java /opt/jdk1.7.0_45/bin/java 1
update-alternatives --install /usr/bin/javac javac /opt/jdk1.7.0_45/bin/javac 1
update-alternatives --install /usr/lib/mozilla/plugins/libjavaplugin.so mozilla-javaplugin.so /opt/jdk1.7.0_45/jre/lib/amd64/libnpjp2.so 1
update-alternatives --set java /opt/jdk1.7.0_45/bin/java
update-alternatives --set javac /opt/jdk1.7.0_45/bin/javac
update-alternatives --set mozilla-javaplugin.so /opt/jdk1.7.0_45/jre/lib/amd64/libnpjp2.so

I am successful up until the --set commands, where I get:

root@lynx:/opt/jdk1.7.0_67# update-alternatives --set java /opt/jdk1.7.0_45/bin/java
update-alternatives: error: alternative /opt/jdk1.7.0_45/bin/java for java not registered; not setting
root@lynx:/opt/jdk1.7.0_67# update-alternatives --set javac /opt/jdk1.7.0_45/bin/javac
update-alternatives: error: alternative /opt/jdk1.7.0_45/bin/javac for javac not registered; not setting
root@lynx:/opt/jdk1.7.0_67# update-alternatives --set mozilla-javaplugin.so /opt/jdk1.7.0_45/jre/lib/amd64/libnpjp2.so
update-alternatives: error: alternative /opt/jdk1.7.0_45/jre/lib/amd64/libnpjp2.so for mozilla-javaplugin.so not registered; not setting

Any ideas? I'm sure it's something simple?