Short version extends means: The new class is a child. It gets benefits coming with inheritance. It has all the properties and methods of its parent. It can override some of these and implement new ones, but the parent stuff is already included. implements means: The new class can be treated as the same “shape”, … Read more
The issue Microsoft/TypeScript#18499 discusses why private members are required when determining compatibility. The reason is: class private members are visible to other instances of the same class. One remark by @RyanCavanaugh is particularly relevant and illuminating: Allowing the private fields to be missing would be an enormous problem, not some trivial soundness issue. Consider this … Read more
First, there is no best practice defined by Android regarding registering click listeners. It totally depends on your use case. Implementing the View.OnClickListener interface to Activity is the way to go. As Android strongly recommends interface implementation over and over again whether it is an Activity or Fragment. Now as you described : public class … Read more
extends is for extending a class. implements is for implementing an interface The difference between an interface and a regular class is that in an interface you can not implement any of the declared methods. Only the class that “implements” the interface can implement the methods. The C++ equivalent of an interface would be an … Read more
“implements Runnable” vs “extends Thread” in Java