Drawing multiple objects in Java [duplicate]

Question

I would like to draw multiple objects like ovals, rectangles and lines together. But somehow I can draw only an object. When I try to draw another shape more, the object I drew is deleted and I can only draw new thing. I've tried to use while loop in the paintComponent Method. But it seems while loop makes the program freeze. I would like to know why it works like that too. How can I solve this?

package package22;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class LecGUI2 {
    // ? 응용 프레임을 생성하고 디스플레이 한다.

    public static void main(String[] args) {
        JFrame frame = new JFrame("Rubber Lines");
        frame.setPreferredSize(new Dimension(500, 500));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new RubberLinesPanel2());
        frame.pack();
        frame.setVisible(true);
    }

}

class RubberLinesPanel2 extends JPanel {
    final int CIRCLE = 0;
    final int LINE = 1;
    final int RECTANGLE = 2;
    private int polygon = LINE;
    private JRadioButton b1, b2, b3;
    private boolean clear = false;

    public RubberLinesPanel2() {
        // 추가하시오
        DrawButtonListener buttonListener = new DrawButtonListener();
        JButton clearButton = new JButton("Clear");
        b1 = new JRadioButton("Circle");
        b2 = new JRadioButton("Line");
        b3 = new JRadioButton("Rectangle");
        b1.addActionListener(buttonListener);
        b2.addActionListener(buttonListener);
        b3.addActionListener(buttonListener);
        clearButton.addActionListener(buttonListener);
        ButtonGroup buttonGroup = new ButtonGroup();
        buttonGroup.add(b1);
        buttonGroup.add(b2);
        buttonGroup.add(b3);
        buttonGroup.add(clearButton);

        add(b1);
        add(b2);
        add(b3);
        DrawPanel drawPanel = new DrawPanel();
        add(drawPanel);
        add(clearButton);
    }

    private class DrawButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            // 추가하시오
            if (b1.isSelected())
                polygon = CIRCLE;
            else if (b2.isSelected())
                polygon = LINE;
            else if (b3.isSelected())
                polygon = RECTANGLE;
            else
                clear = true;
        }

    }

    class DrawPanel extends JPanel {
        private Point point1 = null;
        private Point point2 = null;

        // ? 구성자: 이 패널이 마우스 이벤트들을 감청하도록 설정한다.
        public DrawPanel() {
            LineListener listener = new LineListener();
            addMouseListener(listener);
            addMouseMotionListener(listener);
            setBackground(Color.black);
            setPreferredSize(new Dimension(500, 400));
        }

        public void paintComponent(Graphics page) {
            super.paintComponent(page);
            // 구현하시오
            
            page.setColor(Color.yellow);
            if (point1 != null && point2 != null && polygon == 1)
                page.drawLine(point1.x, point1.y, point2.x, point2.y);
            else if (point1 != null && point2 != null && polygon == 2)
                page.drawRect(point1.x, point1.y, Math.abs(point1.x - point2.x), Math.abs(point1.y - point2.y));
            else if (point1 != null && point2 != null && polygon == 0)
                page.drawOval(point1.x, point1.y, Math.abs(point1.x - point2.x), Math.abs(point1.y - point2.y));

        }

        private class LineListener implements MouseListener, MouseMotionListener {

            public void mousePressed(MouseEvent event) {
                point1 = event.getPoint();
            }

            public void mouseDragged(MouseEvent event) {
                point2 = event.getPoint();
                repaint();
            }

            public void mouseClicked(MouseEvent event) {
            }

            public void mouseReleased(MouseEvent event) {
                repaint();
            };

            public void mouseEntered(MouseEvent event) {
            };

            public void mouseExited(MouseEvent event) {
            };

            public void mouseMoved(MouseEvent event) {
            };
        }
    }

}