Java：包含内部枚举的接口;在实现类中扩展功能

package example;
import java.awt.Point;

public interface Thing {
    public enum MovingState {
        MOVING_LEFT,MOVING_UP,MOVING_RIGHT,MOVING_DOWN
    }

    public void setNewPosition(MovingState state);
    public Point getPosition();
}

和一个实现类：

package example;
import java.awt.Point;

public class ThingImpl implements Thing {
    public enum MovingState {
        MOVING_LEFT (-1,0),MOVING_UP (0,-1),MOVING_RIGHT (1,MOVING_DOWN (0,1);

        private int x_move;
        private int y_move;

        MovingState(int x,int y) {
            x_move = x;
            y_move = y;
        }

        public int xMove() {
            return x_move;
        }

        public int yMove() {
            return y_move;
        }
    }


    private Point position;

    public void setNewPosition(MovingState state) {
        position.translate(state.xMove(),state.yMove());
    }

    public Point getPosition() {
        return position;
    }
}

这个想法是让ThingImpl中的MovingState从Thing界面扩展MovingState(从而将MoveState的实际实现与界面分开).

这不起作用 – ThingImpl中的MovingState枚举会影响接口中的定义,而不是扩展它,然后编译器抱怨ThingImpl不是抽象的,并且不会覆盖Thing中的抽象方法setNewPosition(Thing.MovingState).

有没有实际的方法来做我想要实现的？还是Java根本没有这种能力？