Hello everyone!

I've tried to create objects from classes and it worked until I wanted to draw the new objects I created.

package objectclasstrain;
import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Dimension;
import java.awt.Color;
import java.awt.Graphics;
 
 
 
 
public class ObjectClassTrain {
 
 
 
 
 
 
    public static void main(String[] args) {
 
        square squareRed = new square();
        System.out.println(squareRed.returnXposition());
        System.out.println(squareRed.returnYposition());
 
        SwingUtilities.invokeLater(new Runnable(){
            @Override
            public void run(){
                createAndShowGUI();
            }
        });
 
    }
 
    public static void createAndShowGUI(){
 
        JFrame f = new JFrame("JFrame test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setResizable(false);
        f.add(new myPanel());
        f.pack();
        f.setVisible(true);
 
    }
 
}
 
class myPanel extends JPanel{
 
 
     int room_width = 640;
     int room_height = 480;
 
 
 
 
    public myPanel(){
 
 
 
    }
 
 
 
 
 
 
    @Override
    public Dimension getPreferredSize(){
 
        return new Dimension(room_width, room_height);
 
    }
 
    @Override
    public void paintComponent(Graphics g){
        super.paintComponent(g);        
        g.setColor(Color.BLACK);
        g.fillRect(squareRed.returnXposition(), 0, room_width, room_height);
 
    }
 
 
}
 
 
class square{
 
    int room_width = 640;
     int room_height = 480;
 
    double Xposition;
    double Yposition;
 
         public square(){
 
             Xposition = (int) (Math.random() * room_width);
             Yposition = (int) (Math.random() * room_height);
             }
 
         public double returnXposition(){
             return Xposition;
         }
 
         public double returnYposition(){
             return Yposition;
         }
 
 
}

I don't really know how I could get access to the squareRed's Xposition variable.

oh, and another problem is that there is only one line of code which will paint the objects, and I want to be able, for example,
to click on the screen to create an object which is automatically be painted on the screen. And to do that I can't just create new lines
of code for every object that could be created.

What should I do?