inheritance

问题 Disclaimer: I am new to programming and have just started learning about Classes and Inheritance so perhaps it is my lack of understanding which is causing me issues? I have created two classes in seperate files person.py and address.py . The person class inherits from the address class however a person can have multiple addresses (postal, physical etc..) How can I inherit multiple instances of my address class to for each type. My goal is to eventually have a library of common classes for

问题 Disclaimer: I am new to programming and have just started learning about Classes and Inheritance so perhaps it is my lack of understanding which is causing me issues? I have created two classes in seperate files person.py and address.py . The person class inherits from the address class however a person can have multiple addresses (postal, physical etc..) How can I inherit multiple instances of my address class to for each type. My goal is to eventually have a library of common classes for

问题 I'm very new to java and would like to know whether calling a subclass method in a superclass is possible. And if doing inheritance, where is the proper place to set public static void main . Superclass public class User { private String name; private int age; public User() { //Constructor } //Overloaded constructor public User(String name, int age) { this.name = name; this.age = age; } public String getName() { return this.name; } public static void main(String []args) { User user1 = new

问题 This question already has answers here : Why do I have to access template base class members through the this pointer? (3 answers) Closed 15 days ago . I require some clarification on the question why do we need the scope resolution operator or this pointer to access publicly inherited members from a template base class. As I understand it is for adding clarity but then how does this add any further clarity than just point that it is a member of the class. To make my question clearer I have

问题 This question already has answers here : Why do I have to access template base class members through the this pointer? (3 answers) Closed 15 days ago . I require some clarification on the question why do we need the scope resolution operator or this pointer to access publicly inherited members from a template base class. As I understand it is for adding clarity but then how does this add any further clarity than just point that it is a member of the class. To make my question clearer I have

问题 I want to have a derived class which has a default constructor that initializes the inheirited members. Why can I do this class base{ protected: int data; }; class derived: public base{ public: derived(){ //note data = 42; } }; int main(){ derived d(); } But not this class base{ protected: int data; }; class derived: public base{ public: derived(): //note data(42){} }; int main(){ derived d(); } error: class ‘derived’ does not have any field named ‘data’ 回答1: An object can only be initialized

问题 Is it possible to derive a class from a specialized generic type: TGenericBase <T> = class // ... end; TSpecializedDerived = class (TGenericBase <String>) // ... end; Just wondering if this is possible at all... EDIT Code works fine when I put it in a new project. Must be due to some other mistake; sorry about that 回答1: Yes. I do it all the time. It's very useful. One of my favorite tricks goes something like this: TSpecializedList = class(TObjectList<TMyType>) public (extra methods specific

问题 I have parent class and a child class, both of having a method m1 with same signature (Override), can I call parent class method in following scenario. I dont want to change child class method. // Super class public class Parent { public void m1() { System.out.println("Parent method"); } } // Sub class public class Child extends Parent { @Override public void m1() { System.out.println("Child method"); } } // User class public class Kavi { public static void main(String[] args) { Parent p =

问题 I have parent class and a child class, both of having a method m1 with same signature (Override), can I call parent class method in following scenario. I dont want to change child class method. // Super class public class Parent { public void m1() { System.out.println("Parent method"); } } // Sub class public class Child extends Parent { @Override public void m1() { System.out.println("Child method"); } } // User class public class Kavi { public static void main(String[] args) { Parent p =

问题 I have a requirement where I have a number of classes all derived from a single base class. The base class contains lists of child classes also derived from the same base class. All classes need to be able to obtain specific values which may be obtained from the class itself -OR- it's parent depending on what the derived class is. I looked at using Methods rather than properties however I also want to make the values available to a .NET reporting component which directly accesses exposed