Superclass og subclass...

jeg har følgende kode(3 klasser):

public class Point {
    protected int x,y;
   
    public Point() {
        setPoint(0,0);
        System.out.println(\"Point constructor: \" + toString());
    }
   
    public Point(int a, int b) {
        setPoint(a,b);
        System.out.println(\"Point constructor: \" + toString());
    }
   
    protected void finalize() throws Throwable {
        System.out.println(\"Point finalizer: \" + toString());
        super.finalize();
    }
   
    public void setPoint(int a, int b) {
        x=a;
        y=b;
    }
   
    public int getX() {return x;}

    public int getY() {return y;}

    public String toString() {return \"[\" + x + \", \" + y + \"]\";}
}

public class Circle extends Point{
    protected double radius;
   
    public Circle() {
        setRadius(0);
        System.out.println(\"Circle constructor: \" + toString());
    }
   
    public Circle(double r, int a, int b) {
        super( a, b );
        setRadius(r);
        System.out.println(\"Circle constructor: \" + toString());
    }
   
    protected void finalize() throws Throwable {
        System.out.println(\"Circle finalizer: \" + toString());
        super.finalize();
    }
   
    public void setRadius(double r) {
        radius=(r >= 0? r : 0);
    }
   
    public double getRadius() {return radius;}

    public double area() {return Math.PI * radius * radius;}

    public String toString() {return \"Center = \" + super.toString() + \"; Radius = \" + radius;}
}
import java.awt.Graphics;
import java.applet.Applet;

public class Test extends Applet {
    private Circle circle1, circle2;

    public void init() {
        circle1 = new Circle(4.5, 72, 29);
        circle2 = new Circle(10, 5, 5);
    }
   
    public void start() {
        circle1 = null;   
        circle2 = null;

        System.gc();
    }

    public void paint(Graphics g) {
        g.drawString(\"See command in console\",25,25);
    }
}

Outputtet fra dette er:
Point constructor: Center = [72, 29]; Radius = 0.0
Circle constructor: Center = [72, 29]; Radius = 4.5
Point constructor: Center = [5, 5]; Radius = 0.0
Circle constructor: Center = [5, 5]; Radius = 10.0
Circle finalizer: Center = [72, 29]; Radius = 4.5
Point finalizer: Center = [72, 29]; Radius = 4.5
Circle finalizer: Center = [5, 5]; Radius = 10.0
Point finalizer: Center = [5, 5]; Radius = 10.0

Hvordan kan det være at Radius bliver printet ud når konstruktor og finalizer i point bliver eksekveret???? og hvad refererer super.finalize() i point finalizer motoden til????