extends class and implements interface in java
extends should go before implements: class Sub extends Super implements Colorable {}
extends
How to merge objects?
Copy var src = { name: ‘Apple’, price: 5}; var dst= angular.copy(src); deep copy Extend: var mergedObject = angular.extend(dst, src1, src2, …) shallow copy Merge: var mergedObject = angular.merge(dst, src); since angular 1.4+ deep (recursively) copy If you want to not overwrite with null, you can use this. Object.assign(): let movie2 = Object.assign({}, movie1, { … Read more
how to extend service with dependencies in angular 2
The parameters of the super class need to be repeated and passed to the super call: @Injectable() export class ChildService extends ParentService{ constructor (http:Http, customService:CustomService){ super(http, customService); } } There are some “hacks” to work around like Inheritance and dependency injection
extends and implements in one class in TypeScript
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
Java why interface extends interface
The significant reasons depend entirely on what the interface is supposed to do. If you have an interface Vehicle and an interface Drivable it stands to reason that all vehicles are drivable. Without interface inheritance every different kind of car class is going to require class ChevyVolt implements Vehicle, Drivable class FordEscort implements Vehicle, Drivable … Read more
Scala – extends vs with
If you have multiple classes or traits to inherit, the first one is always extends, and the following >=0 class/trait to be withs. But remember that you can only inherit <=1 (abstract) class, which means if you need to inherit a parent class (Parent), it should always comes at first of the form … extends … Read more
Why “extends” precedes “implements” in class declaration [closed]
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
Generics : List
List<Dog> is a subtype of List<? extends Animal>, but not a subtype of List<Animal>. Why is List<Dog> not a subtype of List<Animal>? Consider the following example: void mySub(List<Animal> myList) { myList.add(new Cat()); } If you were allowed to pass a List<Dog> to this function, you would get a run-time error. EDIT: Now, if we use … Read more
Interface extends another interface but implements its methods
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