~~~ package thread.a5; public class Test { public static void main(String[] args) { Xc8 xc81=new Xc8(); Thread ee = new Thread(xc81); ee.start(); Xc8 xc82=new Xc8(); Thread ff = new Thread(xc82); ff.start(); } } class Xc8 implements Runnable { public static int chepiao = 100;//static只執行一次，共享100張票，否則會是200張 public void run() { while (true) { if (chepiao > 0) { System.out.println("第"+Thread.currentThread().getName()+"個車站正在賣第"+(101-chepiao)+"張車票"); --chepiao; } else { break; } } } } ~~~  程序還是有問題，因為程序執行到一半，另一個線程也開啟了 優化代碼如下 ~~~ package thread.a5; public class Test1 { public static void main(String[] args) { Xc9 xc9=new Xc9(); Thread ee = new Thread(xc9); ee.start(); Thread ff = new Thread(xc9); ff.start(); } } class Xc9 implements Runnable { public static int chepiao = 100; String aa = new String("1"); //字符串隨意定義，定義在函數上邊 //synchronized 的作用是，讓它所管轄的代碼部分，要么全部執行完，要么全部不執行 public void run() //synchronized修飾函數不需要字符串，相當于默認是this { while (true) { synchronized (aa) //既可以修飾代碼塊，又可以修飾函數 { if (chepiao > 0) { System.out.println("第"+Thread.currentThread().getName()+"個車站正在賣第"+(101-chepiao)+"張車票"); --chepiao; } else { break; } } } } } ~~~