How to declare a Generic class variable without knowing its type?

Question

OOP

There is an abstract class

public abstract class Adapter<T> {
            public abstract T onCreateViewHolder(ViewGroup parent);
            public abstract void onBindViewHolder(T holder, int position);
            public abstract int getItemCount();
}

I use it like this:

public class AdapterAudioList: Adapter<VListView> {

        PlayList list;
        public AdapterAudioList(PlayList list){
            this.list = list;
        }
        public override VListView onCreateViewHolder(ViewGroup parent) {
            return new VListView();
        }

        public override void onBindViewHolder(VListView holder, int position) {
            holder.setLabel(list.getAudio(position).artist);
            holder.setLabel2(list.getAudio(position).title);
        }
        public override int getItemCount() {
            return 500;
        }
    }

initialize

AdapterAudioList listx = new AdapterAudioList(list);
recyclerView1.setAdapter(listx);

private Adapter adapter;
 public void setAdapter(Adapter adb) {
            adapter = adb;
}

Right now everything is not working, I tried to inherit from the empty Adapter class and cast it, but I got null.
The question is how to do it right?
I also tried to do this, but it still didn’t cast, maybe I didn’t cast correctly)

public abstract class BaseElement :UserControl {}

public abstract class Adapter<T>:BaseElement {
            public abstract T onCreateViewHolder(ViewGroup parent);
            public abstract void onBindViewHolder(T holder, int position);
            public abstract int getItemCount();
}

Answer 1

You do not declare a universal variable. But you can create a geneticist and work with him through reflection.