Can someone help me to look at how to write, changed many times feel wrong

Create three classes, a main class, a Printer class, and a Thread class.
main class:

public class main {

    public static void main(String[] args) {
        Printer printer = new Printer();
        new Thread(new Employee("李强", printer)).start();
        new Thread(new Employee("王晓", printer)).start();
        new Thread(new Employee("陈明", printer)).start();
    }
    

}

class Printer {
    public synchronized void print(String name) {
        System.out.print(name + "正在使用打印机");
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(name + "使用完毕");
    }
    
}

Employee class:

public class Employee implements Runnable {
    private final String name;
    private final Printer printer;

    public Employee(String name, Printer printer) {
        this.name = name;
        this.printer = printer;
    }

    @Override
    public void run() {
        printer.print(name);
    }
}

There you go

// defines employee threads where the keyword synchronized is a lock and only one thread can access the printer ata time

public class MyThread extends Thread {

      private int count=5; 
        @Override 
        synchronized  public void run()
        { 
            super.run(); 
            count--; 
            //此示例不要用for语句，因为使用同步后其他线程就得不到运行的机会了， 
            //一直由一个线程进行减法运算 
            System.out.println("count="+count); 
        }
    }

// Start the thread,

public class Test {
    public static void main(String[] args)
    { 
        MyThread mythread=new MyThread(); 
        Thread a=new Thread(mythread,"A"); 
        Thread b=new Thread(mythread,"B"); 
        Thread c=new Thread(mythread,"C"); 
        a.start(); 
        b.start(); 
        c.start(); 
    }
}

All three threads run at the same time and print different results.
If synchronized is not added, the printed result may have the same value.