无法创建抽象类或接口的实例
我不熟悉使用抽象类。
我正在尝试调用抽象类并收到此错误无法创建抽象类或接口的实例并且我已经研究了此错误，但我真的很困惑这。
这是我的代码：
string B1String;
while ((B1String = OasisFile.ReadLine()) != null)
{
Questions_Base oQuestions_Base = new Questions_Base(); // error here
oQuestions_Base.Import(B1String);
}
请给我建议..谢谢！
I'm not familiar on using abstract class.
I'm trying to call a abstract class and get this error Cannot create an instance of the abstract class or interface and I already research this error but I'm really confused on this.
Here's my code:
string B1String;
while ((B1String = OasisFile.ReadLine()) != null)
{
Questions_Base oQuestions_Base = new Questions_Base(); // error here
oQuestions_Base.Import(B1String);
}
Please advice me.. thanks!
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抽象类的目的是作为类层次结构的一部分，其中更多派生类共享一些公共实现。
如果您有一个飞行模拟器，您可以定义一个抽象类
ThingsThatFly来实现所有飞行物体都具有的一些属性（空速、高度、航向）和方法（TakeOff()、Land()）常见，但会被声明为抽象，因为 ThingsThatFly 是所有会飞的具体事物的抽象。当然，您也可以在两者之间添加类，例如Cessna172可以继承自Airplane，而Airplane又继承自ThingsThatFly。如果所有飞机都有一些共同的实现，例如鸟类没有的（例如，剩余燃料属性），您就可以这样做。然后，您将拥有许多像塞斯纳 172、航天飞机和鸭子一样飞行的具体（=现实生活）物体。其中每一个都是从
ThingsThatFly派生的具体类，这与让具体类实现诸如
IThingsThatFly之类的接口不同，因为抽象类不仅提供定义预期的属性和方法，而且还提供了这些属性和方法的（希望有用的）实现。The purpose of an abstract class it to serve as part of a class hierarchy where more-derived classes share some common implementation.
If you have a flight simulator, you might define an abstract class
ThingsThatFlythat implements some properties (air speed, altitude, heading) and methods (TakeOff(), Land()) that all flying things have in common, but would be declared abstract because ThingsThatFly is an abstraction of all concrete things that fly. You could certainly have classes inbetween as well, for exampleCessna172could inherit fromAirplanethat inherits fromThingsThatFly. You would do that if all airplanes have some common implementation that e.g. birds don't have (for example, a Fuel Remaining property).You would then have a number of concrete (= real life) things that fly like a Cessna 172, a Space Shuttle and a Duck. Each of those would be a concrete class that derives from
ThingsThatFlyThis is different than having the concrete classes implement an interface such as
IThingsThatFlyin that the abstract class provides not only a definition of the properties and methods that are expected, but also provides a (hopefully useful) implementation of those properties and methods.抽象类只能被继承。
这是一个关于抽象类及其使用方法的链接。
An Abstract class can only be inherited.
Here's a link all about abstract classes and how to use them.
您无法创建抽象类的实例。
您需要定义一个继承抽象类的具体类，并创建它的实例。
You cant create an instance of an abstract class.
You need to define a concrete class that inherits the abstract class, and create an instance of that.
Abstract类被派生类覆盖。如果您必须拥有Abstract类，请首先从中创建Derived类并使用Derived类构造函数。Questions_Base类声明中删除abstract一词，从而使其成为非抽象的。另外，因为在提供的代码中我没有看到任何abstract成员，所以这可能是正确的选择。问候。
Abstractclass is made to be overriden by Derived class. If you have to haveAbstractclass, first create sDerivedclass from it and useDerivedclass contructor.abstractword fromQuestions_Baseclass declaration, so making that non abstract one. Also because in code provided I don't see anyabstractmember, so may this one is correct choice.Regards.
抽象类不能被实例化。您必须为该类提供一个实现。
有关详细信息，请参阅摘要上的 MSDN
An abstract class cannot be instantiated. You must provide an implementation for the class.
See MSDN on abstract for more information
文档中：“abstract 关键字使您能够创建不完整且必须在派生类中实现的类和类成员。”
使用抽象的目的正是为了防止实例化，因为您创建的类只是用作基类，而不想创建实例。
更多信息请参见此处。
From the documentation: "The abstract keyword enables you to create classes and class members that are incomplete and must be implemented in a derived class."
The purpose of using abstract is exactly to prevent instantiation, because you only created the class to use as a base class and never want an instance created.
More here.
抽象类是必须被继承的类。
它介于接口（仅定义类必须实现的接口而没有实现代码）和可以创建其实例的类（定义接口和实现代码）之间。 .NET框架中有几个抽象类，例如CollectionBase。您无法创建 CollectionBase 的实例，它旨在让您创建一个继承它并扩展其功能的类。
您应该能够简单地从 Questions_Base 的类定义中删除 kwy 工作“抽象”，或者创建一个继承自它的新类定义。
An abstract class is one which MUST be inherited.
It falls somewhere between an Interface, which defines only the interface that a class must implement and no implementation code and a class that you can create an instance of which defines both the interface and the implementation code. There are several abstract classes in the .NET framework such as CollectionBase. You cannot create an instance of CollectionBase, it is intended for you to create a class that inherits from it and extends it's capabilities.
You should simpley be able to remove the kwy work "abstract" from your class definition of Questions_Base or create a new class definition that inherits from it.
抽象类在类定义中由关键字abstract 标记，通常用于定义层次结构中的基类。它们的特别之处在于您无法创建它们的实例 - 如果您尝试，您将收到编译错误。相反，您必须按照继承一章中的介绍对它们进行子类化，并创建子类的实例。那么什么时候需要抽象类呢？这实际上取决于你做什么。老实说，您可以在不需要抽象类的情况下走很长的路，但它们对于特定的事物（例如框架）非常有用，这就是为什么您会在 .NET 框架本身中找到相当多的抽象类。一个好的经验法则是，这个名字实际上很有意义——抽象类经常（如果不是总是）用来描述抽象的东西，更多的是概念而不是真实的东西。
Abstract classes, marked by the keyword abstract in the class definition, are typically used to define a base class in the hierarchy. What's special about them, is that you can't create an instance of them - if you try, you will get a compile error. Instead, you have to subclass them, as taught in the chapter on inheritance, and create an instance of your subclass. So when do you need an abstract class? It really depends on what you do. To be honest, you can go a long way without needing an abstract class, but they are great for specific things, like frameworks, which is why you will find quite a bit of abstract classes within the .NET framework it self. A good rule of thumb is that the name actually makes really good sense - abstract classes are very often, if not always, used to describe something abstract, something that is more of a concept than a real thing.