Unchecked cast warning when casting from MyAbstractParameter to T

Question

sorry I know similar questions have been asked before, but none of them solve my current problem.

I currently have something like this:

abstract class MyAbstractParameter{ /* Some methods/parameters */ }

class MyParameter extends MyAbstractParameter { /*more methods/parameters*/ }

abstract class MyAbstractClass<T extends MyAbstractParameter> extends Thread{
    private List<MyAbstractParameter> list;
    public MyAbstractClass(List<MyAbstractParameter> list) { this.list = list; }
    public List<MyAbstractParameter> getList() { return list; }

    public void run() {
        for(MyAbstractParameter e : list) {
             doStuffWithList((T) e); // WARNING IS HERE WHEN CASTING! ! !!
        }
    }
    public abstract void doStuff(T element);
}

class MyClass extends MyAbstractClass<MyParameter> {
    public MyClass(List<MyAbstractParameter> list) { super(list); }
    public void doStuff(MyParameter element) { /* does something */ }
}

I want that the method getList() to always returns a List<MyAbstractParameter> , and it does, however it gives me this warning, and I understand that the reason behind it is that if I send a list of MyOtherParameter extends MyAbstractParameter , the cast would fail, and I will cry.

So I decided to go for private List<? extends MyAbstractParameter> list; private List<? extends MyAbstractParameter> list; , but I had to the modify everything so that there is no problem with this <? ...> <? ...> .

So... Is there another way if doing it, while avoiding to modify everything?
I mean.. like doing something in MyAbstractClass , without using @SuppressWarning("unchecked") .

Answer 1

If every element in the list is supposed to be a an instance of T, then the list should be a List<T> :

abstract class MyAbstractClass<T extends MyAbstractParameter> extends Thread {
    private List<T> list;
    public MyAbstractClass(List<T> list) { this.list = list; }
    public List<T> getList() { return list; }

    public void run() {
        for (T e : list) {
             doStuffWithList(e); 
        }
    }
    public abstract void doStuff(T element);
}