public Book getBookById(long id) { Book book = myBooksById.get(id); if (book != null) { return book; } book = myDatabase.loadBook(id); if (book == null) { return null; } book.loadLists(myDatabase); final ZLFile bookFile = book.File; final ZLPhysicalFile physicalFile = bookFile.getPhysicalFile(); if (physicalFile == null) { // loaded from db addBook(book, false); return book; } if (!physicalFile.exists()) { return null; } FileInfoSet fileInfos = new FileInfoSet(myDatabase, physicalFile); if (fileInfos.check(physicalFile, physicalFile != bookFile)) { // loaded from db addBook(book, false); return book; } fileInfos.save(); try { book.readMetaInfo(); // loaded from db addBook(book, false); return book; } catch (BookReadingException e) { return null; } }