private static List<BookProcessor> createBookProcessors(List<String> bookProcessorNames) {
List<BookProcessor> result = new ArrayList<BookProcessor>(bookProcessorNames.size());
for (String bookProcessorName: bookProcessorNames) {
BookProcessor bookProcessor = null;
try {
bookProcessor = (BookProcessor) Class.forName(bookProcessorName).newInstance();
result.add(bookProcessor);
} catch (Exception e) {
e.printStackTrace();