inheritance

问题 Since I am trying to learn more about OOP (Java) I'm working my way through some literature where I found this 'task'. Unfortunately I am having kind of a hard time since I am pretty new to OOP and I don't have any sample solution to this. Maybe some of you can give me some input so can work my way through this. Define a class hierarchy for these classes: quadrilateral convex quadrilateral trapezoid parallelogram rhombus rectangle square Create an instance of each class if possible Define

问题 I have two classes: class A { public: int i; }; class B : public A { public: int i; }; Suppose that I created an object for class B B b; Is it possible to access A::i using b ? 回答1: Is it possible to access A::i using b? Yes! How about b.A::i ? ;) 回答2: Yes: int main() { B b; b.i = 3; b.A::i = 5; A *pA = &b; B *pB = &b; std::cout << pA->i << std::endl; std::cout << pB->i << std::endl; } 回答3: Yes you can. To find out read this An override method provides a new implementation of a member

问题 This question already has answers here : How to correctly cast a class to an abstract class when using type generics? (3 answers) Closed last year . Casting Deriving Class as Base Class I have a base abstract class which is generic and inherits from IComparable which is defined like below public abstract class BaseClass<T> where T : IComparable { protected readonly T Data; protected BaseClass(T data) { Data = data; } public abstract T Get(); } Then I have defined a classe which inherits from

问题 This question already has answers here : How to correctly cast a class to an abstract class when using type generics? (3 answers) Closed last year . Casting Deriving Class as Base Class I have a base abstract class which is generic and inherits from IComparable which is defined like below public abstract class BaseClass<T> where T : IComparable { protected readonly T Data; protected BaseClass(T data) { Data = data; } public abstract T Get(); } Then I have defined a classe which inherits from

问题 For the latest version of protobuf-net ( r640 folder ), how to best annotate a ProtoMember that is a derived type ? [ProtoBuf.ProtoContract(Name=@"MyBaseTypeProto")] [Serializable] public partial class MyBaseType: ProtoBuf.IExtensible { ... } [ProtoBuf.ProtoContract(Name=@"MyDerivedTypeProto")] [Serializable] public partial class MyDerivedType : MyBaseType, ProtoBuf.IExtensible { ... } [ProtoBuf.ProtoContract(Name=@"MyMessageProto")] [Serializable] public partial class MyMessage : ProtoBuf

问题 I could not find this question anywhere. Based upon my understanding, Inheritance should/might be the subset of Abstraction. 回答1: First of you should be aware, that here is always some leeway in interpreting such terms and concepts. Below is my take on it. Abstraction is the concept while inheritance is a technical realization. Abstraction in general refers to the leaving out of (unnecessary) details. The opposite direction is concretization. Generalization is also often used in this context

问题 Using Xcode 7 Swift 2 I have been researching inheriting Objective C base class in a Swift UIViewController. I have added my Bridging header file correctly and it is correctly part of my project build settings: In my SCS-Bridging-Header.h file I have the following code: #import "UIViewControllerPlus.h" And then I am trying to inherit the Objective C class UIViewControllerPlus in a Swift class: import UIKit class TestBasicTabBarSegueViewController: UIViewControllerPlus { override func

问题 I could not find this question anywhere. Based upon my understanding, Inheritance should/might be the subset of Abstraction. 回答1: First of you should be aware, that here is always some leeway in interpreting such terms and concepts. Below is my take on it. Abstraction is the concept while inheritance is a technical realization. Abstraction in general refers to the leaving out of (unnecessary) details. The opposite direction is concretization. Generalization is also often used in this context

问题 I have two entities where one of them inherits the other one, so I have in jar1 the entity1 and I have a jar2 the entity2->inherits(entity1) in jar1: @Entity public class Entity1 {...} in jar2: @Entity public class Entity2 extends Entity1 {...} So how can I make this to work, it doesn't even compile saying: An annotation processor threw an uncaught exception... Caused by: java.lang.NullPointerException at org.eclipse.persistence.internal.jpa.metadata.accessors.classes.EntityAccessor

问题 While referring JavaDocs for LongAdder, it's extending Number class. Then while looking at source code , It's extending from Striped64 It's quite confusing for me, Why we can't specify in javadocs that LongAdder extending from Striped64 class ? Is it because Striped64 extends Number ? 回答1: Which class does LongAdder extends? As shown in the source, it extends Striped64 . Since that class is not public API, however, the Javadoc doesn't tell you that. Javadoc, by default, only generates