account.java

《java事件处理指南》一书的代码,好东西

class Account
{
   int balance;
   String name;

   public Account(int amt, String nm)
   {
      balance = amt;
      name = nm;
   }

/*  The transfer() method is used to transfer money from the invoking    */
/*  Account object to the one passed as an argument to the method.       */
/*  The transfer() method is synchronized.  It first subtracts the       */
/*  specified amount from the invoking Account object and then adds      */
/*  the same amount to the other Account object.  The subtractBalance()  */
/*  and addBalance() methods are synchronized.  Calling a synchronized   */
/*  method from within a synchronized method can lead to deadlock.       */

   public synchronized void transfer(Account acctB, int amount)
   {
      subtractBalance(amount);

      try
      {
         Thread.sleep(1000);
      }
      catch (Exception e) {}

      System.out.println(Thread.currentThread().getName()+
                            " trying to call addBalance()");
         
      acctB.addBalance(amount);//调用另外一个帐户对象的同步方法可能引起死锁。
   }

   public synchronized void addBalance(int amt) 
   { 
      balance += amt; 
   }

   public synchronized void subtractBalance(int amt) 
   { 
      balance -= amt; 
   }

   public int getBalance() 
   { 
      return balance; 
   }

   public String getName() 
   { 
      return name; 
   }
}