The details are in the
Java™ Language Specification. But it is reluctant to open for me.
Simply: yes. You must initialise all the fields, so as to create your instance in a consistent state, ie fulfilling its class invariants. The only instance where you can get away without a
super(...); call is if the superclass has an accessible no-arguments constructor. One must presume that constructor will put the superclass object into a consistent state.
I think the only state in which case it is good design not to initialise the fields in the superclass is when the superclass hasn't got any fields!