ClassCastException going from interface to object

[Alan Smithee]

Given the class
===================
public class AllStuff implements Serializable {

public List <IBigCar> bigcars;

}


And the following code
=======================

BigCar bc = new BigCar();
bc = (BigCar) this.classname.getAllStuff("uniqueID").getBigCarList().get(0);


This code compiles. Why am I not able to cast an interface from a list to an object?

[Garrett Rowe]

If the runtime type is actually a BigCar then the cast should work. If you are getting a ClassCastException, then the run time type must not be a BigCar.

interface Foo
{
   void bar();
}
 
class DefaultFoo implements Foo
{
   public void bar()
   {
      System.out.println("Default);
   }
 
   public void baz()
   {
      System.out.println("Not defined in Foo interface");
   }
}
 
public class Test
{
   public static void main(String[] args)
   {
      Foo myFoo = new DefaultFoo();
      //myFoo.baz(); //Won't compile
      
      System.out.println("Runtime class = " + myFoo.getClass().getName());
      DefaultFoo asDefault = (DefaultFoo) myFoo;
      asDefault.baz();
   }
}