inheritance

问题 So going back to basics, I'm trying to wrap my head around vtables and whatnot. In the following example, if I were to, say, pass a B* to some function, how does that function know to call the methods in the vtable of the C object instead of the methods from the vtable of A ? Are there two, separate VTables that are passed to that object? Are interface pointers really just vtables (since interfaces, IIRC, cannot contain property declarations)? What I'm trying to say is, up until I actually

问题 This question already has answers here : How does Python's super() work with multiple inheritance? (14 answers) Closed 4 years ago . in multiple inheritance how super() works? for example here I have Two init and I want to send args by super(): class LivingThings(object): def __init__(self, age ,name): self.name=name self.age=age def Print(self): print('age: ', self.age) print('name: ', self.name) class Shape(object): def __init__(self, shape): self.shape=shape def Print(self): print(self

问题 so I have a java class called User that contains a constructor like this: public class User extends Visitor { public User(String UName, String Ufname){ setName(UName); setFname(Ufname); } } And then the he problems occur in my other class called Admin: public class Admin extends User { //error "Implicit super constructor User() is undefined for default constructor. Must define an explicit constructor" //public Admin() { } //tried to add empty constructor but error stays there //} public void

问题 I have a class I am serializing with C#'s XmlSerializer. It is marked with the XmlRoot attribute, and I would like to inherit this attribute in a derived class. Looking at the documentation it does not say that XmlRoot sets Inherit to false with AttributeUsageAttribute (Inherit is supposed to default to true), but I get an error when trying to deserialize my inherited class without an XmlRoot attribute ("<rootNode xmlns=''> was not expected."). This currently works: [Serializable()] [XmlRoot(

问题 I know that there have been similar questions. The examples given in them are too fragmentary and unclear. I need to edit the entities through a form on the page that sends the POST. The standard method is a method in the controller uses the parameter with @ModelAttribute and validator. If one form serves some subclass of an abstract class, there are no problems with the generation of the necessary fields, but there is a problem in the controller. As I understand it, @ModelAttribute works

问题 I know that there have been similar questions. The examples given in them are too fragmentary and unclear. I need to edit the entities through a form on the page that sends the POST. The standard method is a method in the controller uses the parameter with @ModelAttribute and validator. If one form serves some subclass of an abstract class, there are no problems with the generation of the necessary fields, but there is a problem in the controller. As I understand it, @ModelAttribute works

问题 This question already has answers here : Java doesn't support multiple inheritance but implicitly every class in java extends Object and allows one more [duplicate] (8 answers) Closed 4 years ago . In this tutorial (http://www.studytonight.com/java/object-and-classes) I read that a java class may optionally extend one parent class. By default, it will extend java.lang.Object. Note: important statement that i was read that Java enums extend the java.lang.Enum class implicitly, so your enum

问题 While i was reading java book, i came across " Every class extends class Object "...but if want a class B to extend class A.....but Class B will be now having multiple inheritance,one from Object class and one from Class A.How the conflict is resolved. Can anyone explain? 回答1: First of all, Object class is the super/base/parent class of every class including user-defined classes. So even if we don't mention it explicitly, the user-defined classes extends Object class by default. Morevoer,

问题 i have just started learning java::Inheritance and confused while mixing Up-Casting. class Example{ public void methodOne(){ System.out.println("Example::Method_1"); } public void methodTwo(){ System.out.println("Example::Method_2"); } } public class Test extends Example{ public void methodTwo(){ //Method overriding System.out.println("Test::Method_2"); } public void methodThree(){ System.out.println("Test::Method_3"); } public static void main(String[] args){ Example exa = new Test(); //

问题 i have just started learning java::Inheritance and confused while mixing Up-Casting. class Example{ public void methodOne(){ System.out.println("Example::Method_1"); } public void methodTwo(){ System.out.println("Example::Method_2"); } } public class Test extends Example{ public void methodTwo(){ //Method overriding System.out.println("Test::Method_2"); } public void methodThree(){ System.out.println("Test::Method_3"); } public static void main(String[] args){ Example exa = new Test(); //