diff -r 03c5c5dc94e7 -r 58ec6da75f6f task4/solution14/src/org/apidesign/apifest08/currency/ConvertorFactory.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution14/src/org/apidesign/apifest08/currency/ConvertorFactory.java	Sat Oct 11 23:38:46 2008 +0200
@@ -0,0 +1,66 @@
+
+package org.apidesign.apifest08.currency;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public final class ConvertorFactory {
+
+    //Singleton
+    private static ConvertorFactory thisFactory = new ConvertorFactory();    
+    private ConvertorFactory() {};    
+    public static ConvertorFactory newInstance() { //ehm, mistake - it should be named getInstance
+        return thisFactory;
+    }        
+    
+    public Convertor createConvertor(String currency1, String currency2, Rate rate) {
+        return new Convertor(currency1, currency2, rate);
+    }
+    
+    public Convertor createConvertor(String currency1, String currency2, int amount1, int amount2) {
+        return new Convertor(currency1, currency2, new Rate(amount1, amount2));
+    }
+
+    public Convertor createConvertor(String currency1, String currency2, double amount1, double amount2) {
+        return new Convertor(currency1, currency2, new Rate(amount1, amount2));
+    }
+    
+    public Convertor createConvertor(String currency1, String currency2, double rate) {
+        return new Convertor(currency1, currency2, new Rate(rate));
+    }
+
+    public Convertor createConvertor(CurrencyRate currencyRate) {
+        return new Convertor(currencyRate);
+    }
+
+    public Convertor createConvertor(CurrencyRate ... currencyRates) {
+        return new Convertor(currencyRates);
+    }
+
+    public Convertor mergeConvertors(Convertor ... convertors) {
+        if (convertors == null) {
+            throw new IllegalArgumentException("Parameter cannot be null.");
+        }
+        if (convertors.length == 0) {
+            throw new IllegalArgumentException("Convertors cannot be empty.");
+        }
+        List<CurrencyRate> currRates = new ArrayList<CurrencyRate>();
+        List<Pair<String,String>> currPairs = new ArrayList<Pair<String,String>>();
+        for (Convertor convertor : convertors) {
+            if (convertor == null) {
+                throw new IllegalArgumentException("Parameter cannot be null.");                
+            }
+            for (CurrencyRate currRate : convertor.getCurrencyRates()) {
+                Pair<String,String> currPair = new Pair<String,String>(currRate.getCurrency1(), currRate.getCurrency2());
+                if (currPairs.contains(currPair)) {
+                    throw new IllegalArgumentException("Cannot merge - convertors contain same currency rates.");
+                }
+                currPairs.add(currPair);
+                currRates.add(currRate);
+            }
+        }
+        
+        return new Convertor(currRates.toArray(new CurrencyRate[0]));
+    }
+
+}