Generics, oddly enough, use extends for interfaces as well.1 You’ll want to use: public class Foo<T extends SomeInterface>{ //use T as you wish } This is actually a requirement for the implementation, not a true/false check. For a true/false check, use unbounded generics(class Foo<T>{) and make sure you obtain a Class<T> so you have a … Read more
extends should go before implements: class Sub extends Super implements Colorable {}
in runtime i get this Uncaught ReferenceError: MyBaseClass is not defined Yes you can do that. The code you posted will work fine. However I suspect in your actual code you have it split across multiple files and MyBaseClass is not executed before the code for MyClass. Fix JavaScript ordering or use external modules to … 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
When the Java compiler turns a class into bytecode, it must first look to a parent class. That is because the underlying implementation of classes is to point to the bytecode of the parent class – which holds the relevant methods and fields. Then it adds in pointers to the code of the child class … Read more
Why does it implement its methods? How can it implement its methods when an interface can’t contain method body? How can it implement the methods when it extends the other interface and not implement it? What is the purpose of an interface implementing another interface? Interface does not implement the methods of another interface but … Read more
The implements keyword treats the A class as an interface, that means C has to implement all the methods defined in A, no matter if they have an implementation or not in A. Also there are no calls to super methods in C. extends behaves more like what you’d expect from the keyword. You have … Read more
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
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