Abstract class is to avoid object creation
in this, defined and abstract method is possible the abstract method should override.
for example consider "livin_being" as a class in this catagory human ,animal or living being are possible so we can declare generalised class as abstract from this we can extend subclass such human,animal,etc.,
Interface is totally different concept don't relate with abstract
it is just like a template, if we need we can use it, if we use interface we must override because,
all the methods are abstract method. it is one way of achieveing multiple inheritance but java never support multiple inheritance
so don't compare abstract and interface