abstract

Override abstract readonly property to read/write property

由 可紊 提交于 2019-11-27 03:52:49
问题 I would like to only force the implementation of a C# getter on a given property from a base abstract class. Derived classes might, if they want, also provide a setter for that property for public use of the statically bound type. Given the following abstract class: public abstract class Base { public abstract int Property { get; } } If I want a derived class that also implements a setter, I could naively try: public class Derived : Base { public override int Property { get { return field; }

php类abstract和final，类方法abstract和final， interface

由 大憨熊 提交于 2019-11-27 02:11:11
class 类 修饰符 final： 当final作用于某个类时，此类被限定为不可继承类，即其他类无法继承此类，最终类，当你不想让别人继承自己的编写的类时只需要在前面加上final关键字即可 final class MyClass { //code } //fatal error final class MyClass can not be inherited by other class class SubClass extends Myclass { } 当final作用于某个类方法时，此方法被限定为不可重写，即子类中不可以重写此方法，并非不可继承，类方法可否被继承依旧被public protected private限定， 但 即 便父类的fianl private方法无法被子类继承，子类中仍然不能重写此方法 php的继承机制是先检查此方法是不是final，若为final子类中仍重写此方法，则报错 只有在不是final时才会进一步依据public protected private来限定子类是否能继承此方法 且重写追寻访问权限必须宽松于父类的原则 class MyClass { final public function finalPublic() { echo __METHOD__; } final private function finalPrivate() {

Can an enum have abstract methods?

由 萝らか妹 提交于 2019-11-27 02:07:46
问题 Can an enum have abstract methods? If so, what is the use, and give a scenario which will illustrate this usage. 回答1: Yes, but you may prefer enum which implements an interface, Look here. I think It looks much better. This is example for abstract method: public enum Animal { CAT { public String makeNoise() { return "MEOW!"; } }, DOG { public String makeNoise() { return "WOOF!"; } }; public abstract String makeNoise(); } 回答2: Yes, you can define abstract methods in an enum declaration if and

Abstract Method Error

由 久未见 提交于 2019-11-27 02:05:07
I am working on a project in netbeans that when I launch it using the glassfish 3.1.2.Everything works fine.But when i call the /invite url which is mapped to following method @RequestMapping(value = "/invite", method = RequestMethod.POST) @ExceptionHandler(GenericException.class) public ModelAndView create(@ModelAttribute(value = "preRegister") @Valid PreRegister preRegister, BindingResult result, HttpServletRequest request) { mav = new ModelAndView(); validator.validate(preRegister, result); List<Role> roleList = null; if (result.hasErrors()) { mav.setViewName("user_populate_create"); try {

Scala client composition with Traits vs implementing an abstract class

由 限于喜欢 提交于 2019-11-27 01:15:26
问题 I have read that with Scala, it is generally advised to use Traits instead of Abstract classes to extend a base class. Is the following a good design pattern and layout? Is this how Traits were intended to replace Abstract? client class (with def function1) trait1 class (overrides function1) trait2 class (overrides function1) specificClient1 extends client with trait1 specificClient2 extends client with trait2 回答1: I don't know what your source is for the claim that you should prefer traits

Instantiating interfaces in Java

由 家住魔仙堡 提交于 2019-11-27 00:36:30
问题 I have this interface: public interface Animal { public void Eat(String name); } And this code here implements the interface: public class Dog implements Animal { public void Eat(String food_name) { System.out.printf(food_name); } public static void main(String args[]) { Animal baby2 = new Dog(); //HERE!!!!!!!!!!!!!!!!!!!!!! baby2.Eat("Meat"); } } My question is, why does the code work? An interface cannot be instantiated. Yet in this case, interface was instantiated (marked with the comment

Can we use static method in an abstract class?

由 若如初见. 提交于 2019-11-27 00:15:05
问题 In Java Programming, Can we call a static method of an abstract class? Yes I know we can't use static with a method of an abstract class. but I want to know why.. ? 回答1: In Java you can have a static method in an abstract class: abstract class Foo { static void bar() { } } This is allowed because that method can be called directly, even if you do not have an instance of the abstract class: Foo.bar(); However, for the same reason, you can't declare a static method to be abstract. Normally, the

Making a vector of instances of different subclasses

由 旧巷老猫 提交于 2019-11-26 23:24:07
问题 Tried searching, nothing returns( i ithink). Is it possible to make a vector of an abstract class? For example, I have the super class Unit. And I Have the subclasses soldier, vehicle, and bomber. However I would want ever instance of any subclass in one vector, e.g. the vector UnitList can hold instances of both soldier and vehicle? Is this possible? I'm using C++ if it helps. 回答1: Yes, but you'll need to use either pointers or smart pointers (I'd go with this). struct X { virtual ~X() {} //

Java abstract class fields override

由 ☆樱花仙子☆ 提交于 2019-11-26 23:21:08
问题 I have an abstract class that should implement a public field, this field is an interface or another abstract classe. something like this: public abstract class GenericContainer { public GenericChild child; } public abstract class GenericChild { public int prop1=1; } public abstract class SpecialChild extend GenericChild { public int prop1=2; } Now i have another specialized class Container: public abstract class SpecialContainer extends GenericContainer { public SpecialChild child=new

How can I force a Constructor to be defined in all subclass of my abstract class

由 倖福魔咒の 提交于 2019-11-26 22:51:55
问题 I have an abstract class A that define abstract methods. This means that, for a class to be instanciable, all the abstract method have to be implemented. I'd like all my subclasses to implement a constructor with 2 ints as parameters. Declaring a constructor defeats my purpose, as I want the constructor defined in subclasses and I don't know anything about the implementation. Moreover I cannot declare a constructor as being abstract; Is there a way to do this ? Example of what I want: Lets
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