We will focus on the relationship between polymorphism and Java inheritance ... requires an inheritance or an interface implementation. You can see this in the example below, featuring Duke ...

Imagine you are an expert object-oriented Java developer ... create a closed-type system for their components. Sealed classes address precisely the type of inheritance control previously described.

Many mistakenly assume that interfaces only sidestep Java’s failure to support multiple implementation inheritance ... those data items. For example, the integer type identifies a set of ...