java - How to implement a list of a specific concrete class from the abstract class? -

i have abstract class "actor" , should generate list (arraylist, maybe best option) of 1 of concrete classes implemented, lets use "actor1". there 3 or more concrete classes actor1,2,3... made using factory method , of them must have list of actor1(s) created.

any suggestion?

ok, didn't expected such fast response. well, don't start with, of code this, far:

public abstract class actor implements iactor {     protected coordinates coordinates;    protected list<actor> actor1;    public actor(coordinates coordinates) {        this.coordinates = coordinates;           //how implemet list?     }      public coordinates getlocation() {        return coordinates;     }     public void setcoordinates(coordinates coordinates) {        this.coordinates = coordinates;     } 

i make actor generic type bounded itself, , restrict further in concrete subclasses.

public abstract class actor<a extends actor<a>> {      public list<a> getactors() { ...  }  public class actor1 extends actor<actor1> { ... 

that way, getactors actor1 return list<actor1>.