inheritance

问题 here is my scenario: class SomeBaseClass { public void foo(String str) { ....... } public void foo(String strs[]) { ....... } } class MyClass extends SomeBaseClass { public void foo(String str) { super.foo(str); } public void foo(String strs[]) { throw new RuntimeException("only one input please!"); } } The logic is pretty simple. "SomeBaseClass" is 3rd party tool that i cannot modify. I want to limit its functionality and don't want to allow foo(String strs[]). the problem is that inside

问题 Is there a way to force a derived class to use the constructor of the abstract base class? It must not be a real constructor, I have an open mind about creative solutions. class Abstract { private: int Member; string Text; public: Abstract(int Member, string Text) { this->Member = Member; this->Text = Text; } // e.g. defining virtual functions } For example my abstract class has some private members which every derived class should also have. And they should be defined in the constructor,

问题 I saw this code example and was wondering what the purpose of the new() constraint was: public class Client<T> : IClient where T : IClientFactory, new() { public Client(int UserID){ } } 回答1: That's called a "'new' constraint". Here's the documentation on it. The new constraint specifies that any type argument in a generic class declaration must have a public parameterless constructor . To use the new constraint, the type cannot be abstract. (Emphasis mine) Basically, you need it whenever you

问题 I'm trying to understand how JavaScript's prototype-based inheritance works. I was expecting the below outputs would evaluate as true . Why is this? var myStr = "Sample"; String.prototype.isPrototypeOf(myStr); // false Object.prototype.isPrototypeOf(myStr); // false 回答1: JavaScript has both primitive strings and string objects. What you've written there is a primitive string. The Object.prototype.isPrototypeOf method always returns false for any primitive, so your results make sense. If you

问题 I want to implement my own matrix-class that inherits from numpy's matrix class. numpy's matrix constructor requires an attribute, something like ("1 2; 3 4'") . In contrast, my constructor should require no attributes and should set a default attribute to the super-constructor. That's what I did: import numpy as np class MyMatrix(np.matrix): def __init__(self): super(MyMatrix, self).__init__("1 2; 3 4") if __name__ == "__main__": matrix = MyMatrix() There must be a stupid mistake in this

问题 I am running into a hangup while trying to leverage Object.defineProperty() on a base object. I want to inherit properties from that object, using Object.create() , and then define more properties in the derived object (which may be inherited from there). I should note that I am targetting this at node.js. Here's an example: var Base = {}; Object.defineProperty(Base, 'prop1', { enumerable:true, get:function(){ return 'prop1 value';} }); Object.defineProperty(Base, 'prop2', { enumerable:true,

问题 I am running into a hangup while trying to leverage Object.defineProperty() on a base object. I want to inherit properties from that object, using Object.create() , and then define more properties in the derived object (which may be inherited from there). I should note that I am targetting this at node.js. Here's an example: var Base = {}; Object.defineProperty(Base, 'prop1', { enumerable:true, get:function(){ return 'prop1 value';} }); Object.defineProperty(Base, 'prop2', { enumerable:true,

问题 I come across to a strange behavior while trying to override a method with default accessor (ex: void run() ). According to Java spec, a class can use or override default members of base class if classes belongs to the same package. Everything works correctly while all classes loaded from the same classloader. But if I try to load a subclass from separate classloader then polymorphism don't work. Here is sample: App.java: import java.net.*; import java.lang.reflect.Method; public class App {

问题 I found a (at least for me) unexpected behavior when using interface inheritance in Delphi. I have this simple class and interface hierarchy: +---------------+ | << IMyBase >> | +---------------+ ^ | +---------------+ | << IMyIntf >> | +---------------+ ^ | +---------+ | TMyObj | +---------+ I wanted to declare a variable of type IMyBase . Create a TMyObj and assign it to my variable. IHMO this is normal OOP practice. But it turned out that it does not compile. I Have also tried to declare a

问题 package myPackage; public class inheritance { int salary = 50000; } class worker extends inheritance { int bonus = 10000; public static void main(String[] args) { worker obj1 = new worker(); System.out.println("employee salary is" + obj1.salary); System.out.println("employee bonus is" + obj1.bonus); } } Hi.. I am new to java. I am trying to write an inheritance program and getting this error. Error: Main method not found in class myPackage.inheritance, please define the main method as: public