Some help with a program

Question

I have a program that basically simulates a parking meter.
It essentially contains a buffer - which holds the coins prior to processing
A hopper pack - Which contains a collection of 5 change hoppers
Ok - at the moment i have managed to get the system to add coins to the buffer - display the amount and lookup the relevant parking time.
What i am trying to do now is iterate through the buffer ArrayList coin by coin and check to see if the relevant change hopper needs filling up - i have got this to work for first element of the collection but then it doesn't seem to work for subsequent elements. I am not sure why.....
My class files are included below:
import java.util.*;
* Class to implement a facade controller for the ATM software
* (not complete)
* @author  Les Hazlewood
* @version 1.0 written on 23/11/05
public class ATM_System
    // Variables to represent Buffer, Hopper_Pack and Changes objects
    private static Buffer      buffer;
    private static Hopper_Pack hoppers;
    private static Charges     charges;
     * Constructor for objects of class ATM_System
    public ATM_System()
        // To create new Buffer, Hopper_Pack and Changes objects
        buffer  = new Buffer();
        hoppers = new Hopper_Pack();
        charges = new Charges();
        // To initialise the ATM Display and Change Light      
        Hardware.display("0.00");
        Hardware.setLightOff();
     * Method to perform the actions required for the use case :
     * "Insert a coin"
     * @param  coin   The coin inserted into the ATM
    public void insertCoin(Coin coin)
        System.out.println();
        // We need to verify the coin is of the right denomination / Legal coin
        if(coinDetector(coin))
             // We have a legal coin process
             // Add the coin to the buffer
             Hardware.sendDetectorToBuffer(); // Call method from hardware class to print to terminal
             buffer.add(coin);
        else
             // We have a fake/invalid/unrecognised coin - send to reject slot
             Hardware.sendDetectorToReject();
    public static void main(String args[])
         ATM_System atm = new ATM_System();
         Coin five = new Coin(5);
         Coin ten = new Coin(10);
         Coin twenty = new Coin(20);
         Coin pound = new Coin(100);
         atm.insertCoin(five);
        atm.insertCoin(five);
         atm.insertCoin(five);
         atm.pressPrintTicketButton();
         //atm.processBuffer(twenty);
         //System.out.println("Hopper Amount: " + hoppers.returnHopper(0).getHopperAmount());
     * Method to perform the actions required for the use case :
     * "Press the Return Coins Button"
    public void pressReturnCoinsButton()
          // We need to empty everything in the buffer
          buffer.emptyBuffer();
          // Send the coins to refund slot
          Hardware.sendBufferToRefund();
     * Method to perform the actions required for the use case :
     * "Press the Print Ticket Button"
    public void pressPrintTicketButton()
        System.out.println();
        System.out.println("Printing Ticket");
        // Get the relevant charge
        if(buffer.getBufferValue()>=10)
            ParkingPeriodFee thisCharge;
            thisCharge = (ParkingPeriodFee) charges.getCharge(buffer.getBufferValue());
            System.out.println("Minutes: " + thisCharge.getMinutes());
            System.out.println("Fee: " + thisCharge.getFee());
        else
            System.out.println("Not enough");
        // Process the buffer
        ArrayList bufferArray = (ArrayList)buffer.getBuffer();
        for(Iterator iter = bufferArray.iterator(); iter.hasNext();)
            Coin coin = (Coin)iter.next();
            processBuffer(coin);
    public void processBuffer(Coin coin)
         //ArrayList bufferArray = (ArrayList)buffer.getBuffer();
        //System.out.println("--------" + bufferArray.size());
        //int bufferSize = bufferArray.size();
         //for(Iterator iter = bufferArray.iterator(); iter.hasNext();)
            //Coin coin = (Coin)iter.next();
            if(coin.value() == 5)
                 // Process for 5p | Hopper Number 1     
                 if(hoppers.fillHopper(0,coin) == true)
                      // Then we filled the hopper - remove the coin from the buffer
                      buffer.remove(coin);
                 else
                      // Hopper was full so move the coin to the cash box
                      buffer.remove(coin);
                      Hardware.sendBufferToCashBox();
            else if(coin.value() == 10)
                 // Process for 10p Hopper | Hopper Number 2
            else if(coin.value() == 20)
                 // Process for 20p Hopper | Hopper Number 3
            else if(coin.value() == 50)
                 // Process for 50p Hopper | Hopper Number 4
            else if(coin.value() == 100)
                 // Process for �1 Hopper | Hopper Number 5
            else
                 // Something seriously wrong has occured.
                System.out.println("ERROR");
     * Method to perform the role of the coin detector
     *@param coin The coin to pass through the detector
     *@return boolean True if coin is valid false if coin reject
     public boolean coinDetector(Coin coin)
          boolean legal;
          if(coin.value() == 5 || coin.value() == 10 || coin.value() == 20 || coin.value() == 50 || coin.value() == 100)
               // We have a real coin
               legal = true;
          else
               // We have a reject coin
               legal = false;
          // Return our boolean value
          return legal;
     public void distributeCoins(Coin coin)
          // Method to either fill up the hoppers with change OR send to cashbox.
import java.util.*;
/* Hopper_Pack.java - Groups the hoppers into a unit
*@author The Hazelnuts
*@veriso 1.0
public class Hopper_Pack
     private ArrayList pack;
     //private static final int PACK_SIZE = 5; // Only 5 hoppers in each machine
     public Hopper_Pack()
          pack = new ArrayList();
          // Make 5p Hopper
          pack.add(new Hopper(5,1));
          // Make 10p Hopper
          pack.add(new Hopper(10,2));
          // Make 20p Hopper
          pack.add(new Hopper(20,3));
          // Make 50p Hopper
          pack.add(new Hopper(50,4));
          // Make �1 Hopper
          pack.add(new Hopper(100,5));
     public boolean fillHopper(int hopperNo, Coin coin)
          // Create a flag
          boolean flag;
          // We need to see if the required Hopper needs to be filled up
          Hopper workingHopper = (Hopper) pack.get(hopperNo);
          //System.out.println("Hopper 1 Size:" + workingHopper.getSize());
          if(workingHopper.getSize() < 10)
               // Then we will add the coin to the Hopper
               workingHopper.add(coin);
               flag = true; // We did fill the hopper
               System.out.println("Added to hopper: " + workingHopper.getHopperAmount());
          else
               flag = false; // We didn't need to fill the hopper
          return flag;
     public void processBuffer(Buffer buffer)
          // We need to process the buffer to see if the hopper should be filled or not
          ArrayList thisBuffer = buffer.getBuffer();
          for(Iterator iter = thisBuffer.iterator(); iter.hasNext(); )
            Coin coin = (Coin)iter.next();
            if(coin.value() == 5)
                 // Hopper Number for 5p     
            else if(coin.value() == 10)
                 // Process for 10p Hopper
            else if(coin.value() == 20)
                 // Process for 20p Hopper
            else if(coin.value() == 50)
                 // Process for 50p Hopper
            else if(coin.value() == 100)
                 // Process for �1 Hopper
            else
                 // Something seriously wrong has occured.
     public Hopper returnHopper(int hopperNo)
          return (Hopper) pack.get(hopperNo);
import java.util.*;
/* Hopper.java - Simulates a coin hopper
*@Author The Hazelnuts
*@version 1.0
public class Hopper
     private static final int HOPPER_SIZE = 10;
     private ArrayList hopper;
     private int hopperName; // The value of the coins it holds
     private int hopperNumber;
     private int hopperAmount;
     public Hopper(int hopperName, int hopperNumber)
          hopper = new ArrayList();
          this.hopperName = hopperName;
          this.hopperNumber = hopperNumber;
          this.hopperAmount = 0;
     public void add(Coin coin)
          // Add a coin to the hopper
          hopper.add(coin);
          hopperAmount = hopperAmount + coin.value();
     public int getHopperAmount()
          return hopperAmount;
     public int getSize()
          return hopper.size();
     public void remove(Coin coin)
          // Removes a coin from the hopper
          // Sends to refund slot
          hopper.remove(coin);
          hopperAmount = hopperAmount - coin.value();
import java.util.*;
import java.text.DecimalFormat;
* Buffer.java - Buffer Class
*@Author The Hazlenuts
*@Version 1.0
public class Buffer
     private static final int BUFFER_SIZE = 20;   // Maximum size of Array List
     private ArrayList buffer = new ArrayList(); // Holds coin objects
     private int bufferValue;
     public Buffer()
          bufferValue = 0;
     public void add(Coin coin)
          // Add a new coin to buffer
          // Check that the buffer isn't at its maximum size
          if(isEmpty() || buffer.size() < 20) // we are allowed 0-19
               // Then the buffer is ok to add another coin
               buffer.add(coin);
               bufferValue = bufferValue + coin.value();
               Hardware.display(valueString(bufferValue));
               //System.out.println(bufferValue);
               //System.out.println(coin.value());
               //System.out.println(valueString(bufferValue));
          else
               // THe buffer is already full - the coin gets sent to reject slot
               Hardware.sendDetectorToReject();
     public int getBufferValue()
          return bufferValue;
     public boolean isEmpty()
          // Is the ArrayList empty?
          boolean empty = false;
          if(buffer.isEmpty()){empty=true;}
          return empty;
     public void remove(Coin coin)
          // Remove a coin from the buffer
          buffer.remove(coin);
          bufferValue = bufferValue - coin.value();
          Hardware.display(valueString(bufferValue));               
          //System.out.println(bufferValue);
     public String valueString(int bufferAmount)
          double curr = ((double)bufferAmount / 100);
          DecimalFormat df = new DecimalFormat("0.00");
          String buffStr = df.format(curr);
          return buffStr;
     public void emptyBuffer()
          // Empty the buffer on call from System class
        for(Iterator iter = buffer.iterator(); iter.hasNext(); )
            Coin coin = (Coin)iter.next();
            buffer.remove(coin);
        // Set the Hardware Display to �0.00
        Hardware.display("0.00");     
     public ArrayList getBuffer()
          return buffer;
import java.util.*;
/* Charge.java - Holds
public class Charges
     ArrayList feeTable = new ArrayList();
     public Charges()
          // Create our fee table
          feeTable.add(new ParkingPeriodFee(10,15));   // 10p for 15 Minutes
          feeTable.add(new ParkingPeriodFee(20,30));   // 20p for 30 Minutes
          feeTable.add(new ParkingPeriodFee(30,45));   // 30p for 45 Minutes
          feeTable.add(new ParkingPeriodFee(40,60));   // 40p for 60 Minutes
          feeTable.add(new ParkingPeriodFee(80,120));  // 80p for 120 Minutes
          feeTable.add(new ParkingPeriodFee(120,180)); // �1.20 for 180 Minutes
          feeTable.add(new ParkingPeriodFee(160,240)); // �1.60 for 4 Hours
          feeTable.add(new ParkingPeriodFee(200,300)); // �2 for 5 Hours
          feeTable.add(new ParkingPeriodFee(240,360)); // �2.40 for 6 Hours
          feeTable.add(new ParkingPeriodFee(280,420)); // �2.80 for 7 Hours
          feeTable.add(new ParkingPeriodFee(320,480)); // �3.20 for 8 hours
          feeTable.add(new ParkingPeriodFee(360,540)); // �3.60 for 9 Hours
          feeTable.add(new ParkingPeriodFee(400,600)); // �4 for 10 hours
     public ParkingPeriodFee getCharge(int fee)
             // Return a ArrayList of the relevant charge
          //ArrayList thisFee = new ArrayList();
          ParkingPeriodFee highestFee = null;
          for(Iterator iter = feeTable.iterator(); iter.hasNext(); )
                    ParkingPeriodFee charge = (ParkingPeriodFee)iter.next();
                    // Check to see if the current cycle yields acceptable fee
                    if(charge.getFee() <= fee)
                        // We have a new highest fee
                        highestFee = charge;
          //thisFee.add(highestFee);
          return highestFee;
public class ParkingPeriodFee
     private int fee;     // The cost for the parking period
     private int minutes; // The time available for this fee
     public ParkingPeriodFee(int fee, int minutes)
          this.fee = fee;
          this.minutes = minutes;          
     public int getFee()
          // Return Fee
          return this.fee;
     public int getMinutes()
          // Return available minutes
          return this.minutes;
* CLass to simulate the behaviour of the ATM hardware for the purpose
* of testing the ATM Control System software
* @author  Les Hazlewood
* @version 1.0 written on 22/11/05
public class Hardware
     * Method to simulate the action of setting the value shown on the
     * Display by the ATM hardware
     * @param  amount   The value to be shown on the Display
    public static void display(String amount)
        System.out.println("Display shows : �" + amount);
     * Method to simulate the action of setting the Change Light to "OFF"
     * by the ATM hardware
    public static void setLightOff()
        System.out.println("Change Light is OFF");
     * Method to simulate the action of setting the Change Light to "ON"
     * by the ATM hardware
    public static void setLightOn()
        System.out.println("Change Light in ON");
     * Method to simulate the action of sending the coin in the Detector
     * to the coin Reject Slot by the ATM hardware
    public static void sendDetectorToReject()
        System.out.println("Detector coin sent to Reject Slot");
     * Method to simulate the action of sending the coin in the Detector
     * to the Buffer by the ATM hardware
    public static void sendDetectorToBuffer()
        System.out.println("Detector coin sent to Buffer");
     * Method to simulate the action of sending the bottom coin in the
     * Buffer to the coin Refund Slot by the ATM hardware
    public static void sendBufferToRefund()
        System.out.println("Buffer coin sent to Refund Slot");
     * Method to simulate the action of sending the bottom coin in the
     * Buffer to the Cash Box by the ATM hardware
    public static void sendBufferToCashBox()
        System.out.println("Buffer coin sent to Cash Box");
     * Method to simulate the action of sending the bottom coin in the
     * Buffer to a specified Hopper by the ATM hardware
     * @param  num   The number of the hopper
    public static void sendBufferToHopper(int num)
        System.out.println("Buffer coin sent to Hopper number " + num);
     * Method to simulate the action of sending the bottom coin from a
     * specified Hopper to the coin Refund Slot by the ATM hardware
     * @param  num   The number of the hopper
    public static void sendHopperToRefund(int num)
        System.out.println("Coin sent to Refund Slot from Hopper number " + num);
     * Method to simulate the actions of a ticket being printed by the
     * ATM hardware
     * @param  value        The fee paid for the ticket
     * @param  startTime    The clock time at the start of the parking,
     * @param  startDay        together with the corresponding date
     * @param  startMonth      (as day, month name and year) at the start
     * @param  startYear       of the parking period
     * @param  finishTime   The clock time at the end of the parking,
     * @param  finishDay       together with the corresponding date
     * @param  finishMonth     (as day, month name and year) at the end
     * @param  finishYear      of the parking period
    public static void printTicket(String value,
                                   String startTime, String finishTime,
                  String startDay, String startMonth, String startYear,
                  String finishDay, String finishMonth, String finishYear)
        System.out.println("---------------------------------------");
        System.out.println("Aston University Car Parks Ltd - Ticket");
        System.out.println("      Fee paid : �" + value);
        System.out.println("   Time and date      Time and date");
        System.out.println("   at start of        at end of");
        System.out.println("   parking period     parking period");
        System.out.print  ("   " + startTime + " " + startDay + " " +
                                   startMonth + " " + startYear);
        System.out.println("   " + finishTime + " " + finishDay + " " +
                                   finishMonth + " " + finishYear);
        System.out.println("---------------------------------------");
* Class to model a Coin.
* @author Les Hazlewood
* @version 1.0 written on 22/11/05
public class Coin
    // To hold the value of a coin
    private int coinValue;
     * Constructor for objects of class Coin
    public Coin(int value)
        // Valid coins are of 5, 10, 20, 50 and 100 pence denominations.
        // All other values are considered to correspond to an invalid
        // coin, and are represented with a coinValue of 0.
        if ( (value == 5) || (value == 10) || (value == 20) ||
             (value == 50) || (value == 100) )
              coinValue = value;
          else
              coinValue = 0;
     * Method to return the value of the coin
     * @return     The value of the coin
    public int value()
        return coinValue;
     * Method to return if this is a valid coin
     * @return     true if the coin is valid, and false otherwise
    public boolean isValid()
        return (coinValue != 0);
}

Answer 1

After some debugging it appears it is a problem with my loop not progressing...
Any ideas why?
    public void loopTest()
         ArrayList bufferArray = (ArrayList)buffer.getBuffer();
         System.out.println("---");
         System.out.println("Loop Test");
         int i=0;
         for(Iterator iter = bufferArray.iterator(); iter.hasNext();)
              //Print i
              Coin coin = (Coin)iter.next();
              System.out.println(i);
            if(coin.value() == 5)
                 // Process for 5p | Hopper Number 0     
                 if(hoppers.fillHopper(0,coin))
                      // Then we filled the hopper - remove the coin from the buffer
                      buffer.remove(coin);
                 else
                      // Hopper was full so move the coin to the cash box
                      buffer.remove(coin);
                      Hardware.sendBufferToCashBox();
                 //System.out.println(buffer.getBufferValue());
              i++;
    }