1 package com.cn; 2  3 class Test{ 4     public static void main(String [] args){ 5         TestThread t = new TestThread(); 6         new Thread(t).start(); 7         try { 8             Thread.sleep(10); 9         } catch (InterruptedException e) {10             e.printStackTrace();11         }12         t.str="method";13         new Thread(t).start();14     }15 }16 17 class TestThread implements Runnable {18     int tickets = 100;19     String str = new String("");20     public void run() {21         if(str.equals("method")){22             while(true){23                 synchronized (this) {24                     if(tickets>0){25                         try {26                             Thread.sleep(10);27                         } catch (InterruptedException e) {28                             e.printStackTrace();29                         }30                         System.out.println(Thread.currentThread().getName()+" is salling ticket "+tickets--);31                     }32                 }33             }34         }else{35             while(true){36                 sale();37             }38         }39     }40     public synchronized void sale(){41         if(tickets>0){42             try {43                 Thread.sleep(10);44             } catch (InterruptedException e) {45                 e.printStackTrace();46             }47             System.out.println(Thread.currentThread().getName()+" is salling ticket "+tickets--);48         }49     }50 }

sale()方法使用的监视器对象是this，所以要实现同步代码块和sale()方法之间的同步，同步代码块检查的同步对象也应该为this