/**
 * A concrete state for customer shopping
 */
import java.io.*;

public class Pay extends ShopState {
 public static boolean instanceFlag = false; //true if have 1 instance
 private Pay() {
 }
 public static Pay getInstance() {
 if(! instanceFlag) {
 instanceFlag = true;
 return new Pay();
 }
 return null;
 }
 public void pay() {
 System.out.println("The state is pay now !");
 }
}