Java类继承重写列表字段

Question

I am facing a problem, I have a avro generated class A and another B defined like this :

class A {
    String code;
}

class B {
     String someString;
     List<A> codes;
}

And custom classes that extends the two generated classes, described before, like these :

class CustomA extends A {
    String type;
}

class CustomB extends B {
    List<CustomA> codes;
}

It works if I remove the List<> but I realy need it. For the getters/setters, I use lombok @Data annotations.

Do somebody have a solution to work around?

I suppose that the same problème will arrived with a Map<> , so I need a solution too.

Thanks for your answers.

[EDIT] So I will give more concrete examples with these two screenshot below.

Here my classes declarations . As I said before, classes A and B (here User and ToDoItem) are generated classes by an avro schema, so I cannot modify/write in it. Here the compilation errors I have .

Answer 1

You can use generics. Like

class B<T extends A> {
   List<T> codes;
}

class CustomB extends B<CustomA> {
    ...
}

Answer 2

The only way to make that work is generics, as @kiv_apple pointed out . With your generated code, instances of CustomB may always contain references to A instances in the codes list. There is no way you can restrict that without touching the class definition of B .

As this is not possible in your case, you have to find a workaround. One way to go could be defining a custom, differently named getter (without Lombok) that only returns those elements of codes that are instances of CustomB .