Banking system, called thread-safe version

Use synchronized (object) to achieve thread safety

package com.dwz.concurrency.chapter7;

public class TicketWindowRunnable implements Runnable {
    private int index = 1;
    private final static int MAX = 500;
    private final Object MONITOR = new Object();
    
    @Override
    public void run() {
        while(true) {
            synchronized (MONITOR) {
                if(index > MAX) {
                    break;
                }
                
                try {
                    Thread.sleep(5);
                } catch (InterruptedException e) {
                    e.printStackTrace ();
                }
                System.out.println (Thread.currentThread () + "number is:" + (index ++ ));
            }
        }
    }

}

Test code

package com.dwz.concurrency.chapter7;

public class BankVersion2 {
    public static void main(String[] args) {
        TicketWindowRunnable wr = new TicketWindowRunnable();
        Thread thread1 = new Thread(wr, "柜台一");
        Thread thread2 = new Thread(wr, "柜台二");
        Thread thread3 = new Thread(wr, "柜台三");
        
        thread1.start();
        thread2.start();
        thread3.start();
    }
}