如何從派生類初始化基類屬性？

Question

我在我的mvc應用程序中編寫了以下代碼。

public class TestController : Controller
{
    public ActionResult StronglyTypedView()
    {
      var obj = new MvcRouting.Models.Student();
      obj.age = 24;
      obj.name = "prab";
      ViewData.Model = obj;
      return View();
    }
}

在上面的代碼中， ViewData是ControllerBase類的屬性， Model是ViewDataDictionary類的屬性。我在下面的代碼中試過但是我在property1中得到空值，如何解決這個問題？

 public interface Iface1
 {       
    int age { get; set; }
 }
 public class classA : Iface1
 {       
   public int age { get; set; }
 }
 public abstract class classB
 {       
    public classA Property1 { get; set; }
 }
 public class TEST : classB
 {
   public void test()
   {          
      Property1.age = 24;
   }
   public static void Main()
   {
     TEST obj = new TEST();
     obj.test();
     Console.Read();
   }
 }

Answer 1

您將獲得null引用異常，因為您需要在classB初始化Property1

 public interface Iface1
 {       
    int age { get; set; }
 }
 public class classA : Iface1
 {       
   public int age { get; set; }
 }
 public abstract class classB
 {       
    public classA Property1 { get; set; }
 }
 public class TEST : classB
 {
   public void test()
   {    
      if(Property1 == null)
      {
          Property1 = new classA();
      }

      Property1.age = 24;
   }
   public static void Main()
   {
     TEST obj = new TEST();
     obj.test();
     Console.Read();
   }
 }

Answer 2

請改用它。

public abstract class classB
{
 public classA Property1 { get; set; }

 public classB()
 {
   Property1 = new classA();
 }
}

Answer 3

您在設置其屬性之前忘記初始化Property1 。

public class TEST : classB
{
   public void test()
   {    
      Property1 = new classA();
      Property1.age = 24;
   }
   public static void Main()
   {
     TEST obj = new TEST();
     obj.test();
     Console.Read();
   }
}