The more important question is do you really need JAVA at all ?
e.g. do you have an application/s that require JAVA or do you have to visit a site/s that require JAVA. If you can answer no or you don't know if you need it, then the likelihood is that you don't need JAVA.
So rather than update from JAVA 6 to 7 check if you really need it.
In due course the avast software updater would be aware of no further JAVA 6 updates.