VendingMachineMenu.java

import java.util.Scanner;
import java.io.IOException;

/**
   A menu from the vending machine.
*/
public class VendingMachineMenu
{    
   private Scanner in;
   private static Coin[] coins = { new Coin(0.05, "nickel"),
                                   new Coin(0.1, "dime"),
                                   new Coin(0.25, "quarter"),
                                   new Coin(1, "dollar") };

   /**
      Constructs a VendingMachineMenu object
   */
   public VendingMachineMenu()
   {
      in = new Scanner(System.in);
   }
   
   /**
      Runs the vending machine system.
      @param machine the vending machine
   */
   public void run(VendingMachine machine)
         throws IOException
   {
      boolean more = true;
      
      while (more)
      { 
         System.out.println("S)how products  I)nsert coin  B)uy  A)dd product  R)emove coins  Q)uit");
         String command = in.nextLine().toUpperCase();

         if (command.equals("S"))
         {  
            for (Product p : machine.getProductTypes())
               System.out.println(p);
         }
         else if (command.equals("I"))
         { 
            machine.addCoin((Coin) getChoice(coins));
         }
         else if (command.equals("R"))
         {  
            System.out.println("Removed: $" + machine.removeMoney());
         }
         else if (command.equals("B"))
         {              
            try
            {
               Product p = (Product) getChoice(machine.getProductTypes());
               machine.buyProduct(p);
               System.out.println("Purchased: " + p);
            }
            catch (VendingException ex)
            {
               System.out.println(ex.getMessage());
            }
         }
         else if (command.equals("A"))
         {  
            System.out.println("Description:");
            String description = in.nextLine();
            System.out.println("Price:");
            double price = in.nextDouble();
            System.out.println("Quantity:");
            int quantity = in.nextInt();
            in.nextLine(); // read the new-line character
            machine.addProduct(new Product(description, price), quantity);
         }
         else if (command.equals("Q"))
         { 
            more = false;
         }
      }
   }

   private Object getChoice(Object[] choices)
   {
      while (true)
      {
         char c = 'A';
         for (Object choice : choices)
         {
            System.out.println(c + ") " + choice); 
            c++;
         }
         String input = in.nextLine();
         int n = input.toUpperCase().charAt(0) - 'A';
         if (0 <= n && n < choices.length)
            return choices[n];
      }      
   }
}