package junit.samples.money;
   
   /**
    * A simple Money.
    */
   public class Money implements IMoney {
   
       private int fAmount;
       private String fCurrency;
  
      /**
       * Constructs a money from the given amount and currency.
       */
      public Money(int amount, String currency) {
          fAmount = amount;
          fCurrency = currency;
      }
  
      /**
       * Adds a money to this money. Forwards the request to the addMoney helper.
       */
      public IMoney add(IMoney m) {
          return m.addMoney(this);
      }
  
      public IMoney addMoney(Money m) {
          if (m.currency().equals(currency())) {
              return new Money(amount() + m.amount(), currency());
          }
          return MoneyBag.create(this, m);
      }
  
      public IMoney addMoneyBag(MoneyBag s) {
          return s.addMoney(this);
      }
  
      public int amount() {
          return fAmount;
      }
  
      public String currency() {
          return fCurrency;
      }
  
      @Override
      public boolean equals(Object anObject) {
          if (isZero()) {
              if (anObject instanceof IMoney) {
                  return ((IMoney) anObject).isZero();
              }
          }
          if (anObject instanceof Money) {
              Money aMoney = (Money) anObject;
              return aMoney.currency().equals(currency())
                      && amount() == aMoney.amount();
          }
          return false;
      }
  
      @Override
      public int hashCode() {
          if (fAmount == 0) {
              return 0;
          }
          return fCurrency.hashCode() + fAmount;
      }
  
      public boolean isZero() {
          return amount() == 0;
      }
  
      public IMoney multiply(int factor) {
          return new Money(amount() * factor, currency());
      }
  
      public IMoney negate() {
          return new Money(-amount(), currency());
      }
  
      public IMoney subtract(IMoney m) {
          return add(m.negate());
      }
  
      @Override
      public String toString() {
          return "[" + amount() + " " + currency() + "]";
      }
  
      public /*this makes no sense*/ void appendTo(MoneyBag m) {
          m.appendMoney(this);
      }
  }