C# 无法从抽象父类对象访问子公共(public)方法

Question

我正在学习 OOAD 并尝试通过继承来实现类关系，但代码存在问题

父类

namespace ConsoleApplication1
{
    abstract class Classification
    {
        public abstract string type();
    }
}

第一个子类

namespace ConsoleApplication1
{
    class FullTime : Classification
    {
        bool inCampus;
        string roomDetail;
        float rent;

        public FullTime(string studentRoomDetail, float studentRent)
        {
            this.inCampus = true;
            this.roomDetail = studentRoomDetail;
            this.rent = studentRent;
        }

        public FullTime()
        {
            this.inCampus = false;
        }

        public string printAccommodationDescription()
        {
            if (!this.inCampus)
            {
                return "Not in campus";
            }
            else
            {
                return "Room: " + this.roomDetail + " Rent: " + this.rent.ToString();
            }
        }

        public override string type()
        {
            return "fulltime";
        }
    }
}

第二个 child 类(class)

namespace ConsoleApplication1
{
    class PartTime : Classification
    {
        bool onJob;
        string jobTitle;
        float salary;

        public PartTime(string studentJobTitle, float studentSalary)
        {
            this.onJob = true;
            this.jobTitle = studentJobTitle;
            this.salary = studentSalary;

        }

        public PartTime()
        {
            this.onJob = false;
        }

        public string printJobDescription()
        {
            if (!this.onJob)
            {
                return "Not on job";
            }
            else
            {
                return "JobTitle: " + this.jobTitle + " Salary: " + this.salary.ToString();
            }
        }

        public override string type()
        {
            return "parttime";
        }
    }
}

现在在 Program.cs 中，当我尝试从 PartTime 类访问方法 printJobDescription

Classification classification = new PartTime("Software Engineer", 10000);
classification.printJobDescription();

它说

Error CS1061 'Classification' does not contain a definition for 'printAccommodationDescription' and no extension method 'printAccommodationDescription' accepting a first argument of type 'Classification' could be found (are you missing a using directive or an assembly reference?)

我该如何解决这个问题？

更新

我需要让对象在运行时更改其类的能力，因此我必须创建类型为Classification 的对象并使用其他类中未实现的任一方法

Answer 1

您只能使用您使用的类中声明的函数。

abstract class Classification
{
  public abstract string type();
}

class PartTime : Classification
{
  public override string type() {...}
  public Job1() {...}
}

class FullTime : Classification
{
  public override string type() {...}
  public Job2() {...}
}

• Classification类型的对象只能使用type()
• PartTime 类型的对象可以使用 type 和 Job1()
• FullTime 类型的对象可以使用 type 和 Job2()

如果你有这样一个对象:

Classification classification = new PartTime();

并且您不知道是哪种特殊类型，您必须强制转换此对象才能使用其他方法:

if (classification is PartTime)
{
  ((PartTime)classification).Job1();
}
else if (classification is FullTime)
{
  ((FullTime)classification).Job2();
}

希望这对您有所帮助。