Attach classes Observer design pattern [closed]

Hello I was doing this project, but I haven't been able to complete it. I am trying to build an analog clock using the Observer design pattern. My question is: how do I attach the analog clock to the clock timer and then be able to run them in the main method?

I am new to do this subject, please let me know if there are other mistakes.

ClockApp -> main class

package clock;

import clock.analog.AnalogClock;
import clock.timer.ClockTimer;

public class ClockApp {

    public ClockApp() {
        AnalogClock analogClock = new AnalogClock(timer);
        ClockTimer timer = new ClockTimer(analogClock);
        timer.start();
    }
    
    public static void main(String[] args) {
        new ClockApp();
    }
}

Clock Timer

package clock.timer;

import clock.ClockFrame;
import clock.Observable;

import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.logging.Logger;

public class ClockTimer extends Observable implements Runnable {
private long time;

private Calendar calendar;

private long delay = 1000;

private Thread thread;

private static Logger loggingService = Logger.getLogger("ClockTimer");

private ClockFrame clockFrame;

public ClockTimer(ClockFrame clockFrame){
    this.clockFrame = clockFrame;
    calendar = new GregorianCalendar();
}

private int getHour() {
    return calendar.get(Calendar.HOUR_OF_DAY);
}

private int getMinute() {
    return calendar.get(Calendar.MINUTE);
}

private int getSecond() {
    return calendar.get(Calendar.SECOND);
}

@Override
public void run() {
    while (thread != null) {
        try {
            time = System.currentTimeMillis();
            calendar.setTimeInMillis(time);

            notifyObservers(getHour());
            notifyObservers(getMinute());
            notifyObservers(getSecond());

            Thread.sleep(delay);
        } catch (InterruptedException e) {
            loggingService.severe("Timer got interrupted");
        }
    }

}

public void start() {
    if (thread == null) {
        thread = new Thread(this);
        thread.start();
    }
}

public void stop() {
    if (thread != null) {
        thread = null;
    }
}

}

Clock Frame

package clock;

import clock.analog.AnalogClock;
import clock.timer.ClockTimer;
import clock.util.PositionManager;

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

public abstract class ClockFrame extends JFrame implements Observer {

    private ClockTimer timer;
    private ClockPanel clockPanel;

    public ClockFrame(ClockTimer timer){
        super();
        this.timer = timer;

        setFrameTitle();
        addWindowListener(new DetachOnClosingWindowListener());

        clockPanel = createClockPanel();

        getContentPane().add(clockPanel, BorderLayout.CENTER);

        setLocation(PositionManager.getUniqueInstance().getClockWindowPosition());

        // Attach the analog clock to the clock timer
        AnalogClock analogClock = new AnalogClock(this.timer);
        timer.addObserver(analogClock);

        pack();
        setVisible(true);
    }

    protected abstract ClockPanel createClockPanel();

    public abstract void setFrameTitle();

    int hour;
    int minute;
    int second;

    @Override
    public void update(Observable o, Object arg) {
        clockPanel.displayTime(hour, minute, second);
    }

    private class DetachOnClosingWindowListener extends WindowAdapter {
        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    }

}

Analog Clock

package clock.analog;

import clock.ClockFrame;
import clock.ClockPanel;
import clock.timer.ClockTimer;

import java.awt.*;

public class AnalogClock extends ClockFrame {

    private static final long serialVersionUID = 3544948857483180340L;

    public AnalogClock(ClockTimer timer) {
        super(timer);
    }

    protected ClockPanel createClockPanel(){
        AnalogClockPanel clockPanel = new AnalogClockPanel();
        clockPanel.setPreferredSize(new Dimension(400, 400));
        return clockPanel;
    }

    @Override
    public void setFrameTitle() {
        setTitle("Analog Clock");

    }
}