Drawing circle using circle equation directly , on mouse

package drawIT;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.event.MouseInputListener;

public class WindowDraw extends JFrame implements MouseInputListener {

    private Point p1 = new Point();
    private Point p2 = new Point();
    private List list = new ArrayList();
    private Circle circleObj;
    private int clicks = 0;

    public WindowDraw() {

        setTitle("Drawing ");
        addMouseListener(this);
        setLocation(100, 100);
        setSize(500, 500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        g.setColor(Color.white);
        g.fillRect(0, 0, 600, 600);
        g.setColor(Color.red);
        Circle currentCircle;
        for (int i = 0; i < list.size(); i++) {
            currentCircle = (Circle) (list.get(i));
            currentCircle.CircleDirect(g);
        }
    }

    public static void main(String[] args) {
        new WindowDraw();
    }

    @Override
    public void mouseClicked(MouseEvent e) {
    }

    @Override
    public void mousePressed(MouseEvent e) {
        int x = e.getX();
        int y = e.getY();

        if (clicks == 0) {
            circleObj = new Circle();
            circleObj.setCenter(new Point(x, y));

            clicks++;
        } else {
            circleObj.setP2(new Point(x, y));
            circleObj.calRadius();
            list.add(circleObj);
            clicks = 0;
        }
        repaint();
    }

    @Override
    public void mouseReleased(MouseEvent e) {
    }

    @Override
    public void mouseEntered(MouseEvent e) {
    }

    @Override
    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void mouseDragged(MouseEvent e) {
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }
}

class Point {

    private int x;
    private int y;

    public Point() {
    }

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int getX() {
        return x;
    }

    public int getY() {
        return y;
    }

    public void setX(int x) {
        this.x = x;
    }

    public void setY(int y) {
        this.y = y;
    }
}

class Circle {

    private Point center;
    private Point p2;
    private float radius;

    public Circle() {
    }

    public Circle(Point center, Point p2) {
        this.center = center;
        this.p2 = p2;
        radius = (float) Math.sqrt((double) ((center.getX()
                - p2.getX()) * (center.getX() - p2.getX())) + ((center.getY()
                - p2.getY()) * (center.getY() - p2.getY())));
    }

    public Point getCenter() {
        return center;
    }

    public Point getP2() {
        return p2;
    }

    public void setCenter(Point p1) {
        this.center = p1;
    }

    public void setP2(Point p2) {
        this.p2 = p2;
    }

    public void calRadius() {
        radius = (float) Math.round(Math.sqrt((double) ((center.getX()
                - p2.getX()) * (center.getX() - p2.getX())) + ((center.getY()
                - p2.getY()) * (center.getY() - p2.getY()))));
    }

    public void setRadius(float radius) {
        this.radius = radius;
    }

    public float getRadius() {
        return radius;
    }
      void CircleDirect(Graphics g)
      {
           int xc = center.getX();
           int yc = center.getY();
           int R = (int) radius;
           
           int x=0,y=R;
           int R2=R*R;
           Draw8Points(g,xc,yc,x,y);
           while(x<y)
           {
                     x++;
                     y=(int) Math.round(Math.sqrt((double)(R2-x*x)));
                     Draw8Points(g,xc,yc,x,y);
           }
      }

    void Draw8Points(Graphics g,int xc,int yc, int a, int b)
      {
          g.drawOval(xc+a, yc+b, 1,1);
          g.drawOval(xc-a, yc+b, 1,1);
          g.drawOval(xc-a, yc-b, 1,1);
          g.drawOval(xc+a, yc-b, 1,1);
          
          g.drawOval(xc+b, yc+a, 1,1);
          g.drawOval(xc-b, yc+a, 1,1);
          g.drawOval(xc-b, yc-a, 1,1);
          g.drawOval(xc+b, yc-a, 1,1);
           
      }
      
}