多线程问题（生产者和消费者）

class Message {

           privateString title;

           privateString content;

           privateboolean flag = true;

           //flag == true：表示可以生产，但是不能取走

           //flag == false：表示可以取走，但是不能生产

           publicsynchronized void set(String title, String content) {

                     if(this.flag == false) {                                            //已经生产过了，不能生产

                                try{

                                          super.wait();                                                   //等待

                                }catch (InterruptedException e) {

                                          e.printStackTrace();

                                }

                     }

                     this.title= title;

                     try{

                                Thread.sleep(200);

                     }catch (InterruptedException e) {

                                e.printStackTrace();

                     }

                     this.content= content;

                     this.flag= false;                                                      //已经生产完成，修改标志位

                     super.notify();                                                                     //唤醒等待线程

           }

           public synchronized void get() {

                     if(this.flag == true) {                                              //未生产，不能取走

                                try{

                                          super.wait();                                                   //等待

                                }catch (InterruptedException e) {

                                          e.printStackTrace();

                                }

                     }

                     try{

                                Thread.sleep(100);

                     }catch (InterruptedException e) {

                                e.printStackTrace();

                     }

                     System.out.println(this.title+ " --> " +this.content);

                     this.flag = true;                                                       //已经取走了，可以继续生产

                     super.notify();                                                                     //唤醒等待线程

           }

           // setter、getter略

}

}

}