public void SetSearchStrategy(SearchStrategy strategy)
 {
     if (strategy.Equals(SearchStrategy.TITLE))
     {
         this.strategy = new TitleSearch();
     }
     else if (strategy.Equals(SearchStrategy.AUTHOR))
     {
         this.strategy = new AuthorSearch();
     }
     else
     {
         this.strategy = new IsbnSearch();
     }
 }
 public BookService()
 {
     bookrepository = new BookRepositoryHC();
     strategy       = new TitleSearch();
 }