package org.apidesign.apifest08.currency;

 public final class CurrencyRateImpl implements CurrencyRate {

     private String currency1;

     private String currency2;

     private Rate rate;

     CurrencyRateImpl(final String currency1, final String currency2, final Rate rate) {

         if ((currency1 == null)||(currency2 == null) || (rate == null)) {

             throw new IllegalArgumentException("Argument cannot be null.");

         }

         if ("".equals(currency1) || "".equals(currency2)) {

             throw new IllegalArgumentException("Name of currency cannot be empty string");

         }

         if (currency1.equals(currency2)) {

             throw new IllegalArgumentException("Currencies in rate cannot be the same");

         }

         this.currency1 = currency1;

         this.currency2 = currency2;

         this.rate = rate;

     }

     public String getCurrency1() {

         return currency1;

     }

     public String getCurrency2() {

         return currency2;

     }

     public Rate getRate(){

         return rate;

     }

 }