diff -r f6073056b9fe -r a7e6f84fb078 task2/solution13/src/org/apidesign/apifest08/currency/ExchangeRateProvider.java
--- a/task2/solution13/src/org/apidesign/apifest08/currency/ExchangeRateProvider.java	Wed Oct 01 10:43:05 2008 +0200
+++ b/task2/solution13/src/org/apidesign/apifest08/currency/ExchangeRateProvider.java	Tue Oct 07 01:18:23 2008 +0200
@@ -3,27 +3,33 @@
 
 import java.math.BigDecimal;
 import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
- * Exchange rate provider - can provide fixed exchange rate which does not depend
- * on date (method {@link #getExchangeRate()} ) or exchange rate based on date (method {@link #getExchangeRate(java.util.Date) }).
+ * Exchange rate provider. Provides fixed exchange rate which does not depend
+ * on date (method {@link #getExchangeRate()} ).
  * 
+ * Date dependend exchange rate to be implemented.
  * 
  * @author arnostvalicek
  */
 public class ExchangeRateProvider {
     BigDecimal fromValue, toValue;
     ConvertorCurrency fromCurrency, toCurrency;
+    
+    Map exchangeRateMap = new HashMap();
 
     /**
      * Simple constructor for <code>ExchangeRateProviderM</code> which can provide fixed exchange rate.
      * 
-     * Describes conversion <em>from</em> to <em>to</em> currency.
+     * Describes conversion <em>from ONE</em> to <em>to ONE</em> currency.
      * 
      * @param fromValue From value. BigDecimal value, precision should be set to currency precision.
      * @param fromCurrency From currency.
      * @param toValue To value. BigDecimal value, precision should be set to currency precision.
      * @param toCurrency To currency.
+     * @deprecated deprecated since task2. Use {@link #createExchangeRateProvider() } instead of this constructor.
      */
     public ExchangeRateProvider(BigDecimal fromValue, ConvertorCurrency fromCurrency, BigDecimal toValue, ConvertorCurrency toCurrency) {
         this.fromValue = fromValue;
@@ -32,18 +38,89 @@
         this.toCurrency = toCurrency;
     }
     
+    private ExchangeRateProvider() {
+        
+    }
+    
+    /**
+     * Static method to create new exchange rate provider. This exchange rate provider does not contain
+     * any exchange rates (this is difference to public constructor).
+     * @return New <code>ExchangeRateProvider</code>
+     */
+    public static ExchangeRateProvider createExchangeRateProvider() {
+        ExchangeRateProvider provider = new ExchangeRateProvider();
+        return provider;
+    }
+    
+    /**
+     * Add new exchange rate to <code></code> to this exchange rate provider.
+     * <p>
+     * Example of specifiing conversion rate: 100 SKK == 80 CZK:<br>
+     * <code>addFixedCurencyRate(ConvertorCurrency.getInstance("SKK"), new BigDecimal(100), ConvertorCurrency.getInstance("CZK"),  new BigDecimal(80));</code>
+     * <p>
+     * 
+     * @param fromCurrency Source currency.
+     * @param fromValue Valye for from currency.
+     * @param toCurrency Target currency.
+     * @param toValue Value for target currency.
+     */
+    public synchronized void addFixedCurencyRate(ConvertorCurrency fromCurrency, BigDecimal fromValue, ConvertorCurrency toCurrency, BigDecimal toValue) {
+        if (fromValue==null) {
+            throw new NullPointerException("fromValue can't be null");
+        }
+        if (toValue==null) {
+            throw new NullPointerException("toValue can't be null");
+        }
+        Map map2 = (Map) exchangeRateMap.get(fromCurrency);
+        if (map2==null) {
+            map2 = new HashMap();
+            exchangeRateMap.put(fromCurrency, map2);
+        }
+        
+        ExchangeRate rate = new ExchangeRate(fromValue, toValue);
+        map2.put(toCurrency, rate);
+    }
+    
     /**
      * Get fixed exange rate for currencies (from->to).
      * @return Returns exchange rate.
+     * @deprecated deprecated since task2. Use {@link #getExchangeRate(ConvertorCurrency, ConvertorCurrency) }
      */
     public ExchangeRate getExchangeRate() {
         return new ExchangeRate(fromValue, toValue);
     }
+
+    
+    /**
+     * Get fixed exange rate for currencies (from->to).
+     * @return Returns exchange rate or <code>null</code> if exchange rate not found.
+     */
+    public ExchangeRate getExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {
+        return getExchangeRateImpl(fromCurrency, toCurrency);
+    }
+    
+    /**
+     * Get fixed exange rate for currencies (from->to) or reversed exchange rate (to->from).
+     * @return Returns exchange rate or <code>null</code> if exchange rate not found.
+     */
+    public ExchangeRate getReversibleExchangeRate(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {
+       ExchangeRate rate = getExchangeRateImpl(fromCurrency, toCurrency);
+       if (rate==null) {
+           ExchangeRate revertedRate = getExchangeRateImpl(toCurrency, fromCurrency);
+           if (revertedRate!=null) {
+            rate = ExchangeRate.createRevertedRate(revertedRate);
+           }
+       }
+       return rate;
+    }
+        
+
     
     /**
      * Get exchange rate for currencies (from->to) based on provided date.
      * @param date Date for which exchange rate should be provided.
      * @return Returns exchange rate 
+     * @deprecated deprecated since task2. No real implementation in version2.
      */
     public ExchangeRate getExchangeRate(Date date) {
         return new ExchangeRate(fromValue, toValue);
@@ -57,6 +134,19 @@
     ConvertorCurrency getToCurrency() {
         return toCurrency;
     }
+
+    private ExchangeRate getExchangeRateImpl(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency) {
+        if (fromValue != null && toValue != null && fromCurrency.equals(this.fromCurrency) && toCurrency.equals(this.toCurrency)) {
+            return new ExchangeRate(fromValue, toValue);
+        }
+        //return new ExchangeRate(fromValue, toValue);
+        Map map2 = (Map) exchangeRateMap.get(fromCurrency);
+        if (map2 == null) {
+            return null;
+        }
+        ExchangeRate result = (ExchangeRate) map2.get(toCurrency);
+        return result;
+    }
     
 
 }