package test.visitor;
public abstract class Payment {
   interface Visitor {
      Object visit(CardPayment payment);
      Object visit(CashPayment payment);
   }
   public abstract Object accept(Visitor visitor);
}


package test.visitor;
public class CardPayment extends Payment {
   @Override
   public Object accept(Visitor visitor) {
      return visitor.visit(this);
   }
}


package test.visitor;
public class CashPayment extends Payment {
   @Override
   public Object accept(Visitor visitor) {
      return visitor.visit(this);
   }
}


package test.visitor;
public class PaymentDisplayStringVisitor implements Payment.Visitor {
   public Object visit(CardPayment payment) {
      return "CC";
   }
   public Object visit(CashPayment payment) {
      return "CS";
   }
}


package test.visitor;
import java.util.ArrayList;
import java.util.List;
public class Test {

   public static void main(String[] args) {
      List<Payment> payments = new ArrayList<Payment>();
      payments.add(new CashPayment());
      payments.add(new CardPayment());
      
      PaymentDisplayStringVisitor visitor = new PaymentDisplayStringVisitor();
      for (Payment payment : payments) {
         System.out.println(payment.accept(visitor));
      }
   }
}