package junit.samples.money;import java.util.ArrayList;import java.util.List;/** * A MoneyBag defers exchange rate conversions. For example adding  * 12 Swiss Francs to 14 US Dollars is represented as a bag  * containing the two Monies 12 CHF and 14 USD. Adding another * 10 Swiss francs gives a bag with 22 CHF and 14 USD. Due to  * the deferred exchange rate conversion we can later value a  * MoneyBag with different exchange rates. * * A MoneyBag is represented as a list of Monies and provides  * different constructors to create a MoneyBag.  */ public class MoneyBag implements IMoney {	private List<Money> fMonies= new ArrayList<Money>(5);	public static IMoney create(IMoney m1, IMoney m2) {		MoneyBag result= new MoneyBag();		m1.appendTo(result);		m2.appendTo(result);		return result.simplify();	}	public IMoney add(IMoney m) {		return m.addMoneyBag(this);	}	public IMoney addMoney(Money m) { 		return MoneyBag.create(m, this);	}	public IMoney addMoneyBag(MoneyBag s) {		return MoneyBag.create(s, this);	}	void appendBag(MoneyBag aBag) {		for (Money each : aBag.fMonies)			appendMoney(each);	}	void appendMoney(Money aMoney) {		if (aMoney.isZero()) return;		IMoney old= findMoney(aMoney.currency());		if (old == null) {			fMonies.add(aMoney);			return;		}		fMonies.remove(old);		Money sum= (Money) old.add(aMoney);		if (sum.isZero()) 			return;		fMonies.add(sum);	}	@Override	public boolean equals(Object anObject) {		if (isZero())			if (anObject instanceof IMoney)				return ((IMoney)anObject).isZero();		if (anObject instanceof MoneyBag) {			MoneyBag aMoneyBag= (MoneyBag)anObject;			if (aMoneyBag.fMonies.size() != fMonies.size())				return false;		    for (Money each : fMonies)		        if (! aMoneyBag.contains(each))					return false;			return true;		}		return false;	}	private Money findMoney(String currency) {		for (Money each : fMonies)			if (each.currency().equals(currency))				return each;		return null;	}	private boolean contains(Money m) {		Money found= findMoney(m.currency());		if (found == null) return false;		return found.amount() == m.amount();	}	@Override	public int hashCode() {		int hash= 0;	    for (Money each : fMonies)	        hash^= each.hashCode();	    return hash;	}	public boolean isZero() {		return fMonies.size() == 0;	}	public IMoney multiply(int factor) {		MoneyBag result= new MoneyBag();		if (factor != 0)			for (Money each : fMonies)				result.appendMoney((Money) each.multiply(factor));		return result;	}	public IMoney negate() {		MoneyBag result= new MoneyBag();	    for (Money each : fMonies)	        result.appendMoney((Money) each.negate());		return result;	}	private IMoney simplify() {		if (fMonies.size() == 1)			return fMonies.iterator().next();		return this;	}	public IMoney subtract(IMoney m) {		return add(m.negate());	}	@Override	public String toString() {		StringBuffer buffer = new StringBuffer();		buffer.append("{");		for (Money each : fMonies)		    buffer.append(each);		buffer.append("}");		return buffer.toString();	}	public void appendTo(MoneyBag m) {		m.appendBag(this);	}}