三种实现方式

继承Thread类，synchronized同步代码块

public class SellTicket extends Thread {

    // 多个对象共享，必须static修饰
    private static int tickets = 100;

    @Override
    public void run() {
        while (true) {
            synchronized (SellTicket.class) {
                try {
                    sleep(1000);
                } catch (Exception e) {
                    e.printStackTrace();
                }
                if (tickets > 0) {
                    System.out.println(getName() + " 正在出售第 " + tickets-- + " 张票");
                }
            }
        }
    }
}

public class TicketDemo {

    public static void main(String[] args){
        SellTicket thread01 = new SellTicket();
        SellTicket thread02 = new SellTicket();
        SellTicket thread03 = new SellTicket();

        thread01.setName("窗口一");
        thread02.setName("窗口二");
        thread03.setName("窗口三");

        thread01.start();
        thread02.start();
        thread03.start();
    }
}

实现runnable接口，同步代码块

public class SellTicket2 implements Runnable {

    // 多个对象共享，必须static修饰
    private static int tickets = 100;

    @Override
    public void run() {
        while (true) {
            synchronized (SellTicket2.class) {
                if (tickets > 0) {
                    try {
                        Thread.sleep(1000);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() + " 正在出售第 " + tickets-- + " 张票");
                }
            }
        }
    }
}

public class TicketDemo2 {

    public static void main(String[] args) {
        SellTicket2 sellTicket2 = new SellTicket2();

        Thread thread01 = new Thread(sellTicket2);
        Thread thread02 = new Thread(sellTicket2);
        Thread thread03 = new Thread(sellTicket2);

        thread01.setName("窗口一");
        thread02.setName("窗口二");
        thread03.setName("窗口三");

        thread01.start();
        thread02.start();
        thread03.start();
    }
}

实现runable接口，Lock锁实现线程安全

public class SellTicket3 implements Runnable {

    // 多个对象共享，必须static修饰
    private static int tickets = 100;

    private Lock lock = new ReentrantLock();

    @Override
    public void run() {
        while (true) {
            lock.lock();
            if (tickets > 0) {
                try {
                    Thread.sleep(1000);
                } catch (Exception e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName() + " 正在出售第 " + tickets-- + " 张票");
            }
            lock.unlock();
        }
    }
}

public class TicketDemo3 {

    public static void main(String[] args) {
        SellTicket3 sellTicket3 = new SellTicket3();

        Thread thread01 = new Thread(sellTicket3);
        Thread thread02 = new Thread(sellTicket3);
        Thread thread03 = new Thread(sellTicket3);

        thread01.setName("窗口一");
        thread02.setName("窗口二");
        thread03.setName("窗口三");

        thread01.start();
        thread02.start();
        thread03.start();
    }
}