Question

我在理解如何实现继承方面遇到了一些麻烦。

我的模型纯粹是出于示范的目的，但我们走了：

我有一个家长班Bus。它有两个孩子DieselBus和ElectricBus。这些是抽象类。

我还有两个班级Coach和CityBus。如何将这些内容设置为从DieselBus或ElectricBus继承而不必定义单独的Coach和CityBus类，例如CoachDieselBus，CoachElectricBus ，CityBusDieselBus和CityBusElectricBus？这甚至可行/可能吗？

到目前为止，我没有关于一些骷髅的例子，在这一点上寻求建议。

我在寻找的是： Correct

与此相反： Incorrect

谢谢！

编辑（2013-07-03）：

首先，一些代码：

Bus.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InheritanceTest {
    abstract class Bus {
        public Bus () {

        }

        public abstract Engine EngineType {
            get;
            set;
        }

        private int id;
        public int ID {
            get {
                return id;
            }
            set {
                id = value;
            }
        }

        private int seats;
        public int Seats {
            get {
                return seats;
            }
            set {
                seats = value;
            }
        }

        private float length;
        public float Length {
            get {
                return length;
            }
            set {
                length = value;
            }
        }

        private String colour;
        public String Colour {
            get {
                return colour;
            }
            set {
                colour = value;
            }
        }
    }
}

Coach.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InheritanceTest {
    class Coach : Bus {
        public Coach (int id, int seats, float length, String colour, String company, Engine engine) {
            this.ID = id;
            this.Seats = seats;
            this.Length = length;
            this.Colour = colour;
            this.EngineType = engine;
            this.company = company;
        }

        public override Engine EngineType {
            get;
            set;
        }

        private String company;
        public String Company {
            get {
                return company;
            }
            set {
                company = value;
            }
        }

        public override string ToString () {
            return (this.ID + "\t" + this.Seats + "\t" + this.Length + "\t" + this.Colour + "\t" + this.Company + "\t" + this.EngineType.ToString ());
        }
    }
}

Engine.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InheritanceTest {
    abstract class Engine {
        public Engine () {

        }

        private float power;
        public float Power {
            get {
                return power;
            }
            set {
                power = value;
            }
        }

        private float torque;
        public float Torque {
            get {
                return torque;
            }
            set {
                torque = value;
            }
        }

        private int redline;
        public int Redline {
            get {
                return redline;
            }
            set {
                redline = value;
            }
        }
    }
}

DieselEngine.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InheritanceTest {
    class DieselEngine : Engine {
        public DieselEngine (float power, float torque, int redline, float displacement, float fuelEconomy) {
            this.Power = power;
            this.Torque = torque;
            this.Redline = redline;
            this.displacement = displacement;
            this.fuelEconomy = fuelEconomy;
        }

        private float displacement;
        public float Displacement {
            get {
                return displacement;
            }
            set {
                displacement = value;
            }
        }

        private float fuelEconomy;
        public float FuelEconomy {
            get {
                return fuelEconomy;
            }
            set {
                fuelEconomy = value;
            }
        }

        public override string ToString () {
            return "Diesel Engine";
        }
    }
}

我的程序执行有问题：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace InheritanceTest {
    class Program {
        static void Main (string[] args) {
            String line;
            var diesel = new DieselEngine (200F, 550F, 3500, 7.5F, 10F);
            var electric = new ElectricEngine (85F, 1000F, 19000, 24F, 65000F);
            var city = new CityBus (124, 75, 18.5F, "Red", "Brisbane", electric);
            var coach = new Coach (777, 120, 22.5F, "Blue", "GreyHound", diesel);
            line = new String ('-', city.ToString ().Length * 2);

            System.Console.WriteLine ("City Buses\n\nID\tSeats\tLength\tColour\tCity\t\tEngine Type");
            System.Console.WriteLine (line);
            System.Console.WriteLine (city.ToString ());

            System.Console.WriteLine ("\n\nCoach Buses\n\nID\tSeats\tLength\tColour\tCompany\t\tEngine Type");
            System.Console.WriteLine (line);
            System.Console.WriteLine (coach.ToString ());

            System.Console.ReadKey (true);
        }
    }
}

无论我如何尝试，我都无法访问从相关总线继承引擎的任何类的任何属性。例如，我看不到Displacement DieselEngine给Coach“教练的{{1}}。”

Answer 1

我还有两个课程Coach和CityBus。如何设置继承DieselBus或ElectricBus，而不必定义单独的Coach和CityBus类，如CoachDieselBus，CoachElectricBus，CityBusDieselBus和CityBusElectricBus？这甚至可行/可能吗？

不，那不可行。继承关系必须已修复，因此Coach必须始终具有相同的父类。

针对您的问题的适当解决方案是使用合成而不是继承：Coach和CityBus都继承自Bus。 Bus具有Engine属性，可以设置为DieselEngine或ElectricEngine。

Diagram

（对不起粗略的图表，我现在只有MS Paint可用。）

Answer 2

像往常一样，当这个问题到来时，混乱开始于一个不可行的类树。我个人会说，这些都不是继承问题。

公共汽车有一个发动机，它是DieselEngine和ElectricEngine的基础。

公共汽车的用法可能是City and Coach的基类。

这里使用继承是一种经典的反模式。一个典型的初学者错误 - 所以不要为此感到难过。结果主要是太复杂的继承树。

您也可以使用接口（IDieselEngine，IElectricEngine），但我可能会使用它。

Answer 3

在C＃中，您只能从一个类继承，因此只能使用第二个图中显示的类。

您可以使用接口，因为类可以实现多个接口，但接口应该更多地用于定义行为，而不是类和属性/质量的类和柴油/电动和城市/教练看起来更像是公共汽车的属性。 / p>

Answer 4

这是一个如何做你想做的事的例子

public abstract class Engine
{
    public abstract string Name { get; set; }
}

public class DieselEngine:Engine
{
    public override string Name { get; set; }

    public string DieselEngineProperty { get; set; }
}

public class ElectricEngine : Engine
{
    public override string Name { get; set; }

    public string ElectricEngineProperty { get; set; }
}

public class HybridEngine : Engine
{
    public override string Name { get; set; }

    public string HybridEngineProperty { get; set; }
    public List<Engine> EngineList { get; set; }
}



public abstract class Bus
{
    public abstract string Name { get; set; }
    public abstract string Lengh { get; set; }
    public abstract Engine BusEngine { get; set; }
}

public class CoachBus: Bus
{
    public override string Name { get; set; }

    public string CoachBusProperty { get; set; }
}

public class CityBus:Bus
{

    public override string Name { get; set; }
    public override string Lengh { get; set; }
    public override Engine BusEngine { get; set; }

    public string CityBusProperty { get; set; }
}

这里有一些巴士

        var myDieselEngine = new DieselEngine();
        myDieselEngine.Name = "TöffTöff";

        var myElectricEngine = new ElectricEngine();
        myDieselEngine.Name = "SumSum";

        var myHybridEngine = new HybridEngine();
        myDieselEngine.Name = "SumTöff";

        var myDieselCityBus = new CityBus();
        myDieselCityBus.Name = "Shorty1";
        myDieselCityBus.Lengh = "5 m";
        myDieselCityBus.BusEngine = myDieselEngine;

        var myElectricCityBus = new CityBus();
        myElectricCityBus.Name = "Shorty2";
        myElectricCityBus.Lengh = "7 m";
        myElectricCityBus.BusEngine = myElectricEngine;

        var myHybridCoachBus = new CoachBus();
        myHybridCoachBus.Name = "Shorty2";
        myHybridCoachBus.Lengh = "15 m";
        myHybridCoachBus.BusEngine = myHybridEngine;

在C＃中解决继承问题

4 个答案: