JPanel в JFrame

package main;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
 
 
interface gridPanel{
    void paintChildren(Graphics g);
}
 
public class Dots {
 
public static void main(String args[]){
 
    WindowMain ml = new WindowMain("Dots Game");
    ml.setVisible(true);
}
 
}
 
class WindowMain extends JFrame  {
 
    private final int DEFUALT_WIDTH=600;
    private final int DEFAULT_HEIGHT=500;
    private Container container = new Container();
 
    WindowMain (String name){
        setTitle(name);
        setSize(DEFUALT_WIDTH, DEFAULT_HEIGHT);
        setLocationRelativeTo(null);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        add(new CellPane());
    }
 
 
 
}
 
class CellPane extends JPanel  implements gridPanel{
 
    private final int scale=19;
    private int ArrayCells[][];
    private final int DEFAULT_WIDTH=456;
    private final int DEFAUTL_HEIGHT=456;
 
    CellPane()
    {
        setBackground(Color.WHITE);
        setSize(DEFAULT_WIDTH,DEFAUTL_HEIGHT);
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                super.mouseClicked(e);
                System.out.print("Clicked");
            }
        });
    }
 
    @Override
    public void paintChildren(Graphics g) {
        super.paintChildren(g);
       // g.setColor(Color.WHITE);
       // g.fillRect(0,0,DEFAULT_WIDTH,DEFAUTL_HEIGHT);
        g.setColor(Color.LIGHT_GRAY);
        for(int X=0;X<DEFAULT_WIDTH;X+=scale)
            for(int Y=0;Y<DEFAUTL_HEIGHT;Y+=scale){
                g.drawLine(X,0,X,DEFAUTL_HEIGHT);
                g.drawLine(0,Y,DEFAULT_WIDTH,Y);
            }
        repaint();
    }
 
}

class WindowMain extends JFrame  {
 
    private final int DEFUALT_WIDTH=600;
    private final int DEFAULT_HEIGHT=500;
    private Container container = new Container();
 
    WindowMain (String name){
        setTitle(name);
        setSize(DEFUALT_WIDTH, DEFAULT_HEIGHT);
        setLocationRelativeTo(null);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        CellPane cp= new CellPane();
        Container content = getContentPane();
        content.add(cp);
    }
 
 
 
}
 
class CellPane extends JPanel  implements gridPanel{
 
    private final int scale=19;
    private int ArrayCells[][];
    private final int DEFAULT_WIDTH=456;
    private final int DEFAUTL_HEIGHT=456;
 
    CellPane()
    {
 
 
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                super.mouseClicked(e);
                Graphics g; g=getGraphics();
                Graphics2D g2= (Graphics2D) g;
                g2.draw(new Ellipse2D.Double(10,10,10,10));
                repaint();
            }
        });
    }
 
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        setBorder(BorderFactory.createLineBorder(Color.LIGHT_GRAY));
        setSize(DEFAULT_WIDTH,DEFAUTL_HEIGHT);
        g.setColor(Color.WHITE);
        g.fillRect(0,0,DEFAULT_WIDTH,DEFAUTL_HEIGHT);
        g.setColor(Color.LIGHT_GRAY);
        for(int X=0;X<DEFAULT_WIDTH;X+=scale)
            for(int Y=0;Y<DEFAUTL_HEIGHT;Y+=scale){
                g.drawLine(X,0,X,DEFAUTL_HEIGHT);
                g.drawLine(0,Y,DEFAULT_WIDTH,Y);
            }
    }
 
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package cyberforum;
 
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.util.ArrayList;
import java.util.List;
 
/**
 *
 * @author BleStaR
 */
public class NewJFrame extends javax.swing.JFrame {
    
    private List<Point> points = new ArrayList<>();
    
    /**
     * Creates new form NewJFrame
     */
    public NewJFrame() {
        initComponents();
    }
 
    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {
 
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        addMouseListener(new java.awt.event.MouseAdapter() {
            public void mouseClicked(java.awt.event.MouseEvent evt) {
                formMouseClicked(evt);
            }
        });
 
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );
 
        pack();
    }// </editor-fold>                        
 
    private void formMouseClicked(java.awt.event.MouseEvent evt) {                                  
        points.add(evt.getPoint());
        repaint();
    }                                 
 
    @Override public void paint(Graphics g) {
        super.paintComponents(g); //To change body of generated methods, choose Tools | Templates.
        g.setColor(Color.red);
        for(int i = 0 ; i < 300; i+=30) {
            g.drawLine(i, 0, i, 300);
            g.drawLine(0, i, 300, i);
        }
        for(int i = 0; i < points.size(); i++) {
            g.fillOval(points.get(i).x, points.get(i).y, 10, 10);
        }
    }
    
    
    
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see [url]http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html[/url] 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>
 
        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new NewJFrame().setVisible(true);
            }
        });
    }
 
    // Variables declaration - do not modify                     
    // End of variables declaration                   
}