phonecard.java

关于隐藏域抽象域的例子

class PhoneCard
{
   long cardNumber;
   private int password;
   double balance;
   String connectNumber;
   boolean connected;

   boolean performConnection(long cn,int pw)
   {
     if(cn==cardNumber&&pw==password)
     {
       connected=true;
       return true;
     }
     else
     {
       connected=false;
       return false;
     }
   }
   double getBalance()
   {
     if(connected)
        return balance;
     else
        return -1;
  }
  void performDial()
  {
     if(connected)
        balance-=0.5;
  }
}