Скачать или смотреть Embrace Java Generics with Lower Bound Type Parameters

Explore how to use generic functions with a lower bound in Java, enabling you to create reusable and type-safe code that operates on a specific set of related types, such as superclasses or more general interfaces.

In the code example above, we create a Fruit class and an Apple class that extends it. We then create a generic function addFruit that accepts a list of objects of a type that is a superclass or a more general interface of Apple (indicated by the super keyword). This lower bound ensures that the function can only be called with types that are related to Apple as a superclass or more general interface.

Finally, we create a list of Apple objects and call the addFruit function with this list, which results in adding a new Apple object to the list and printing the updated size of the list. Note that in this example, we are using the lower bound to allow insertion of elements into the list, which is a common use case for lower bounds in Java Generics.