接口与抽象类 [英] interface vs abstract class

问题描述

可能重复：

接口或抽象类？

我有一组定义的类如下：

I have a group of classes defined as follows:

namespace VGADevices.UsingAbstractClass
{
    public abstract class VGA
    {
        public abstract int HorizontalResolution { get; set; }
        public abstract int VerticalResolution { get; set; }
    }
    public class LCDScreen : VGA
    {
        public override int HorizontalResolution { get; set; }
        public override int VerticalResolution { get; set; }
    }
}  // namespace VGADevices.UsingAbstractClass

namespace VGADevices.UsingInterfaces
{
    public interface IVGA
    {
        int HorizontalResolution { get; set; }
        int VerticalResolution { get; set; }
    }
    public class LCDScreen : IVGA
    {
        public virtual int HorizontalResolution { get; set; }
        public virtual int VerticalResolution { get; set; }
    }
}  // namespace VGADevices.UsingInterfaces

客户端代码，I可以选择：

Client code, I have the choice between:

class Computer
{
        public VGA VGAOutput { get; set; }
}

或

class Computer
{
        public IVGA VGAOutput { get; set; }
}

我在某处读到使用接口更好，但为什么？
使用抽象类我可以定义一个接口以及添加数据成员，那么为什么接口是首选方法呢？
二元替换在这里也起作用吗？

I read somewhere that using interfaces is better, but why? With abstract classes I can define an interface as well plus add data-members so why are interfaces the preferred method? Does binary replacement play a role here as well?

谢谢

Chris

推荐答案

您可以继承（即实现）多个接口。您不能从多个抽象类继承

You can inherit from(that is, implement) multiple interfaces. You can't inherit from multiple abstract classes

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