Tuple.java

// extracting the first tuple from the list
Tuple bookGenreTuple = bookGenreTuples.get(0);

// getting the first element of the tuple 
// and converting it into a Book object
Book book = bookGenreTuple.get(0, Book.class);

// getting the second element of the tuple
// and converting it into a Genre object
Genre genre = bookGenreTuple.get(1, Genre.class);