Java线程：线程的同步-同步方法

/** 
* Java线程：线程的同步 
* 
* @author leizhimin 2009-11-4 11:23:32 
*/ 
public  class Test { 
         public  static  void main(String[] args) { 
                User u =  new User( "张三", 100); 
                MyThread t1 =  new MyThread( "线程A", u, 20); 
                MyThread t2 =  new MyThread( "线程B", u, -60); 
                MyThread t3 =  new MyThread( "线程C", u, -80); 
                MyThread t4 =  new MyThread( "线程D", u, -30); 
                MyThread t5 =  new MyThread( "线程E", u, 32); 
                MyThread t6 =  new MyThread( "线程F", u, 21); 

                t1.start(); 
                t2.start(); 
                t3.start(); 
                t4.start(); 
                t5.start(); 
                t6.start(); 
        } 
} 

class MyThread  extends Thread { 
         private User u; 
         private  int y = 0; 

        MyThread(String name, User u,  int y) { 
                 super(name); 
                 this.u = u; 
                 this.y = y; 
        } 

         public  void run() { 
                u.oper(y); 
        } 
} 

class User { 
         private String code; 
         private  int cash; 

        User(String code,  int cash) { 
                 this.code = code; 
                 this.cash = cash; 
        } 

         public String getCode() { 
                 return code; 
        } 

         public  void setCode(String code) { 
                 this.code = code; 
        } 

         /** 
         * 业务方法 
         * @param x 添加x万元 
         */ 
         public  synchronized  void oper( int x) { 
                 try { 
                        Thread.sleep(10L); 
                         this.cash += x; 
                        System.out.println(Thread.currentThread().getName() +  "运行结束，增加“" + x +  "”，当前用户账户余额为：" + cash); 
                        Thread.sleep(10L); 
                }  catch (InterruptedException e) { 
                        e.printStackTrace(); 
                } 
        } 

        @Override 
         public String toString() { 
                 return  "User{" + 
                                 "code='" + code + '\'' + 
                                 ", cash=" + cash + 
                                '}'; 
        } 
}

void notify()    
                    唤醒在此对象监视器上等待的单个线程。    
void notifyAll()    
                    唤醒在此对象监视器上等待的所有线程。    
void wait()    
                    导致当前的线程等待，直到其他线程调用此对象的 notify() 方法或 notifyAll() 方法。    
void wait( long timeout)    
                    导致当前的线程等待，直到其他线程调用此对象的 notify() 方法或 notifyAll() 方法，或者超过指定的时间量。    
void wait( long timeout,  int nanos)    
                    导致当前的线程等待，直到其他线程调用此对象的 notify() 方法或 notifyAll() 方法，或者其他某个线程中断当前线程，或者已超过某个实际时间量。