Wildcards (?) solve the problem that List<Dog> is not a List<Animal>. They let you write methods that work with generic types in a flexible but still type-safe way. There are three kinds: unbounded (?), upper-bounded (? extends T), and lower-bounded (? super T).
Unbounded Wildcard — ?
Content is available with subscription.
Get full access to all courses on the platform for one year with a single payment.
▼
Unlike other platforms that charge per course, here you get everything for one price, and after one year of use there will be no automatic charge for the following year.