import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock; public class IntegerDemo {  public static void main(String[] args) {    // 創建3個線程對象    SellTicket st = new SellTicket();     Thread t1 = new Thread(st, "窗口1");    Thread t2 = new Thread(st, "窗口2");    Thread t3 = new Thread(st, "窗口3");     // 啟動線程    t1.start();    t2.start();    t3.start();  }} class SellTicket implements Runnable {  private int ticket = 100;  private Lock lock = new ReentrantLock();   public void run() {    while (true) {      lock.lock();       if (ticket > 0) {        try {          Thread.sleep(100);        } catch (InterruptedException e) {          // TODO Auto-generated catch block          e.printStackTrace();        }         System.out.println(Thread.currentThread().getName() + "正在出售第" + (ticket--) + "張票。");      }       lock.unlock();    }  }}