I am having some trouble working out how defining constructors in interfaces work. I might be totally misunderstanding something. But I have searched for answers for a good while and I can not find anything related to this. How do I implement the following interface in a TypeScript class: interface MyInterface { new ( … … Read more
In Java, it is perfectly legal to define final arguments in interface methods and do not obey that in the implementing class, e.g.: public interface Foo { public void foo(int bar, final int baz); } public class FooImpl implements Foo { @Override public void foo(final int bar, int baz) { … } } In the … Read more
I’m at a point in my development learning where I feel like I must learn more about interfaces. I frequently read about them but it just seems like I cannot grasp them. I’ve read examples like: Animal base class, with IAnimal interface for things like ‘Walk’, ‘Run’, ‘GetLegs’, etc – but I’ve never been working … Read more
Consider an example (which compiles in java) public abstract interface Interface { public void interfacing(); public abstract boolean interfacing(boolean really); } Why is it necessary for an interface to be “declared” abstract? Is there other rules that applies with an abstract interface? Finally: If abstract is obsolete, why is it included in Java? Is there … Read more
How does one go about and try to find all subclasses of a given class (or all implementors of a given interface) in Java? As of now, I have a method to do this, but I find it quite inefficient (to say the least). The method is: Get a list of all class names that … Read more
I recently watched a Tutorial on Angular 2 with TypeScript, but unsure when to use an Interface and when to use a Model for data structures. Example of interface: export interface IProduct { ProductNumber: number; ProductName: string; ProductDescription: string; } Example of Model: export class Product { constructor( public ProductNumber: number, public ProductName: string, public … Read more
Since multiple inheritance is bad (it makes the source more complicated) C# does not provide such a pattern directly. But sometimes it would be helpful to have this ability. For instance I’m able to implement the missing multiple inheritance pattern using interfaces and three classes like that: public interface IFirst { void FirstMethod(); } public … Read more
I have just found a static nested interface in our code-base. class Foo { public static interface Bar { /* snip */ } /* snip */ } I have never seen this before. The original developer is out of reach. Therefore I have to ask SO: What are the semantics behind a static interface? What … Read more
Interfaces allow you to create code which defines the methods of classes that implement it. You cannot however add any code to those methods. Abstract classes allow you to do the same thing, along with adding code to the method. Now if you can achieve the same goal with abstract classes, why do we even … Read more
For example, suppose I want an ICar interface and that all implementations will contain the field Year. Does this mean that every implementation has to separately declare Year? Wouldn’t it be nicer to simply define this in the interface? 12 Answers 12