Extending a class with a container

Question

Here's the thing: I have a set of classes that extend a basic one. All of them have a container that holds objects of the same type (for example, class C1 has a vector of C1s).
In the old days, I had to cast to get the correct type in each getter. I was wondering if somehow I could set the type of the container now.
I know with generics I can do Vector<C1> v, but the declaration of the vector is in the basic class, So I would still have to cast in the subclasses...
Is there a way to do what I want?
Thanks,
Cesar

Answer 1

Make your base class parameterized:
import java.util.*;
public class Base<T> {
    private List<T> list = new ArrayList<T>();
    public void add(T object) {
        list.add(object);
    public String getMessage() {
        return toString() + ": " + list.toString();
}And derive accordingly:
import java.util.*;
public class Derived extends Base<Derived>{
    private String name;
    public Derived(String name) {
        this.name = name;
    public String toString() {
        return name;
    public static void main(String[] args) {
        Derived d = new Derived("dad");
        d.add(new Derived("hello"));
        d.add(new Derived("world"));
        //d.add(new Base()); //syntax error
        System.out.println(d.getMessage());
}