为什么列出接口而不是类

Question

My doubt is between a simple class with implementations of methods and an interface. not the abstract class. Why cant we just make a List Class , give all the method implementations and make Array List or Linked list to extend it. arent the implementations of methods same.

Answer 1

No, the implementations are not the same. A linked list contains a collection of doubly linked nodes and is optimized for fast insertion/removal. An array list is backed by an array of references and is optimized for random access, but will be less efficient as elements are added and removed.

Defining List as an interface allows callers to apply list-based semantics regardless of the internal details.

Answer 2

In Java, multi-inheritance is not possible. So if a class extends another class, it cannot extend anything else. Whereas implementing an interface is unrestrained. You can implement multiple interfaces with one class.