extends

Here is what I know: Double is a subtype of Number and List<Double> is not a subtype of List<Number> . List<Dog> is not a subtype of List<Animal> because you can add Cat to List<Animal> but you can't do that with List<Dog> . List<? extends Number> means this list can store variables of type Number and variables of subtype of Number. List<Double> means this list can store variables of type Double. Please correct me if anything above is wrong and then Is List<Double> a subtype of List<? extends Number> and why? There are a few points that should also be added At runtime List<Double> , List<?

How do I call a super constructor in Dart? Is it possible to call named super constructors? Eduardo Copat Yes, it is, the syntax is close to C# , here is an example with both default constructor and named constructor: class Foo { Foo(int a, int b) { //Code of constructor } Foo.named(int c, int d) { //Code of named constructor } } class Bar extends Foo { Bar(int a, int b) : super(a, b); } class Baz extends Foo { Baz(int c, int d) : super.named(c, d); } If you want to initialize instance variables in the subclass, the super() call must be last in an initializer list. class CBar extends Foo { int

I was wondering if you could help me out.. I have two classes, one extends the other.. Class B will be extended by various different objects and used for common database interactions.. Now I would like class B to handle its connect and disconnects without direction from class A or any external input.. The problem from what I understand is that an extended class won't automatically run its __construct function.. Is there a way around this? Thanks in advance.. class a extends b { public function __construct() { } public function validateStuff() { $this->insert_record(); } } class b { public

I need to create a base view which all my views would extends. I'm not really sure where and when to declare this view. Basically, I need to inject global variables to all my templates and I don't do to that in each and every render() methods. this is my tree structure for now: |-main.js |-app.js |-require.js |-App | |-View | | |-Dashboard.js | | |-Header.js | | |-Content.js | |-Model | |-Collection | |-Template | |-Libs |-... this is my app.js var App = { ApiURL: "http://domain.local", View: {}, Model: {}, Collection: {}, Registry: {}, Router: null }; define(['backbone', 'View/Dashboard'],

I have Table field as Templates. For this Table field I have form data created with anotation @FormData(value = AbstractMyTableData.class, sdkCommand = FormData.SdkCommand.USE, defaultSubtypeSdkCommand = FormData.DefaultSubtypeSdkCommand.CREATE) public abstract class MyTableField extends AbstractTableField<MyTableField.Table> Inside MyTableField.Table I have n column and all of them is presented in form data for this field, so I can add rows like : int rowNum = formData.addRow(); formData.setColumn_1(rowNumber, value); .... formData.setColumn_n(rowNumber, value); Now I want to extend my table

I just came across this while reading some code and I have absolutely no idea what it means. I tried googling and whatnot but I got nothing, probably due to a lack of vocabulary. The code: public final class GeneralPath extends Path2D.Float { // code and whathaveyou } What I know so far: So I dont have any questions regarding the "public final class ClassName extends" portion, but I don't understand the presence of the dot/scope-resolution operator in the superclass designation. For starters, I imagine that someone is going to say something like "Java doesn't have a scope-resolution operator"

A friend of mine found this tidbit in the Java API ( https://docs.oracle.com/javase/7/docs/api/java/lang/Enum.html ), Class Enum<E extends Enum<E>> and by reading the following article https://docs.oracle.com/javase/tutorial/java/generics/genTypes.html I could understand what the aforementioned line entailed syntactically but from the examples given I could not figure out a use case for this beyond the Enum class (reviewed the source). I'd like to learn more about possible problems where the above may present a solution. It's for example useful to to allow subclasses to use their own type

Question How can you extend a python property? A subclass can extend a super class's function by calling it in the overloaded version, and then operating on the result. Here's an example of what I mean when I say "extending a function": # Extending a function (a tongue-in-cheek example) class NormalMath(object): def __init__(self, number): self.number = number def add_pi(self): n = self.number return n + 3.1415 class NewMath(object): def add_pi(self): # NewMath doesn't know how NormalMath added pi (and shouldn't need to). # It just uses the result. n = NormalMath.add_pi(self) # In NewMath,