从基类 C# 调用子类方法

Question

是否可以从基类引用中调用子类方法？请建议...

代码示例如下：

public class Parent
{
    public string Property1 { get; set; }
}

public class Child1:Parent
{
    public string Child1Property { get; set; }
}
public class Child2 : Parent
{
    public string Child2Property { get; set; }
}

public class Program
{
    public void callMe()
    {
        Parent p1 = new Child1();
        Parent p2 = new Child2();

        //here p1 & p2 have access to only base class member.
        //Is it possible to call child class memeber from the base class reference based on the child class object it is referring to?
        //for example...is it possible to call as below:
        //p1.Child1Property = "hi";
        //p2.Child1Property = "hello";
    }
}

Answer 1

实际上，您已经创建了 Child1 和 Child2 实例，因此您可以投射给它们：

  Parent p1 = new Child1();
  Parent p2 = new Child2();

  // or ((Child1) p1).Child1Property = "hi";
  (p1 as Child1).Child1Property = "hi";
  (p2 as Child2).Child2Property = "hello";

要检查 cast 是否成功，请测试null：

  Child1 c1 = p1 as Child1;

  if (c1 != null)
    c1.Child1Property = "hi";

然而，更好的设计是分配给Child1 和Child2 局部变量

   Child1 p1 = Child1(); 
   p1.Child1Property = "hi";