How can I make graphics moving when I press start button and stop when I press stop button.(Java)

Question

I am working on my first college project. I just start coding. I am making a washing machine for this project.

How can I make my graphics rotate when pressed the start button and stop when I pressed the stop button? Also, I have a countdown timer, once it times out, my graphics will stop rotating as well. (They are in different packages).

Here is my code(Main, first package)

package Main;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import Timer.*;

    public class WashingMachine extends JPanel implements ActionListener{
        JFrame frame = new JFrame("Washing Machine");
        JLabel label_numCloth = new JLabel("Number of Clothes");
        JTextField num_tf = new JTextField("",10);
        JButton com_bt = new JButton("Compute");
        JButton start_bt = new JButton("Start");
        JButton stop_bt = new JButton("Stop");
        JLabel label_cost = new JLabel("Cost: ");   
        JLabel label_price = new JLabel("1 Kg = 4 Baht");
        JPanel panel_num = new JPanel();
        JPanel panel_cost = new JPanel();
        JPanel panel_r = new JPanel();
        JPanel panel_l = new JPanel();
        JPanel panel_start_stop = new JPanel();
        static double cost;
        
    WashingMachine(){ 
        
        panel_num.setLayout(new GridLayout(3,1));
        panel_num.add(label_numCloth);
        panel_num.add(num_tf);
        panel_num.add(com_bt);
        panel_cost.setLayout(new GridLayout(2,1));
        panel_cost.add(label_cost);
        panel_cost.add(label_price);
        panel_start_stop.setLayout(new GridLayout(1,2));
        panel_start_stop.add(start_bt);
        panel_start_stop.add(stop_bt);
        panel_l.add(panel_start_stop);
        panel_r.setLayout(new BorderLayout());
        panel_r.add(panel_num,BorderLayout.NORTH);
        panel_r.add(panel_cost,BorderLayout.CENTER);

        frame.add(this);
        setLayout(new BorderLayout());
        frame.add(panel_r,BorderLayout.EAST);
        frame.add(panel_l,BorderLayout.WEST);
        frame.setBackground(Color.BLACK);
        frame.setSize(250,250);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        label_price.setForeground(Color.red);
        
        com_bt.addActionListener(this);
        start_bt.addActionListener(this);
        stop_bt.addActionListener(this);
     }

    public void actionPerformed(ActionEvent e) {
        //Calculate price
        double cloth = Double.parseDouble(num_tf.getText());
        cost = cloth*4;
        label_cost.setText("Cost: " + cost + " " + "Baht");
        
        if(e.getSource() == start_bt) {
            repaint();
            Simulation sim = new Simulation(); 
            Countdown cout_d = new Countdown();
         if(e.getSource() == start_bt) {
             repaint();
             
         }
        }
    
    }
    }

Here is my code (Simulation for washing machine,second package)

package Timer;

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;


public class Simulation extends JPanel implements ActionListener{
    JFrame frame = new JFrame("Simulation and Timer");
    Timer timer = new Timer(500, this);
    int startAngle = 0;
    int shift =5;
    
    
    public Simulation(){
        timer.start();
        frame.add(this);
        frame.setSize(500,500);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    
    
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.black);
        g.fillOval(87,90,275,275);
        g.setColor(new Color(0,255,255));
        g.fillOval( 100,100 ,250,250 );
        g.setColor(Color.white);
        g.fillOval(275,120,20,20);
    }

    public void actionPerformed(ActionEvent e){
    }
}

package Timer;

import java.awt.Font;
import java.awt.event.*;
import javax.swing.*;
import java.text.DecimalFormat;
import java.awt.*;

public class Countdown {
    
    JFrame frame = new JFrame("Countdown Clock");
    JLabel counter_label = new JLabel("");
    Timer timer;    
    private int second = 0;
    private int minute = 40;
    String ddSecond;
    String ddMinute;    
    DecimalFormat dFormat = new DecimalFormat("00");
    Font font = new Font("Arial",Font.BOLD,20);

    public static void main(String[] args) {
        
        new Countdown();        
    }
    
    public Countdown() {
        
    
        frame.setSize(300,300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(null);
        counter_label.setBounds(120, 100,50 ,50 );
        counter_label.setHorizontalAlignment(JLabel.CENTER);
        counter_label.setFont(font);
        frame.setBackground(Color.black);
        frame.add(counter_label);
        frame.setVisible(true);
        counter_label.setText("40:00");
        countdownTimer();
        timer.start();                      
    }
    
    public  void countdownTimer() {
        
        timer = new Timer(1000, new ActionListener() {
            
            public void actionPerformed(ActionEvent e) {
                
                second--;
                ddSecond = dFormat.format(second);
                ddMinute = dFormat.format(minute);  
                counter_label.setText(ddMinute + ":" + ddSecond);
                
                if(second==-1) {
                    second = 59;
                    minute--;
                    ddSecond = dFormat.format(second);
                    ddMinute = dFormat.format(minute);  
                    counter_label.setText(ddMinute + ":" + ddSecond);
                }
                if(minute==0 && second==0 ) {
                    timer.stop();
                }
            }
        });     
    }       
}