public class Person { @Position(start = 1, length = 10) private String name; @Position(start = 11, length = 3) private int age; // Getter and Setter methods } FlatFileReader<Person> reader = new FlatFileReader<>(Person.class, "data.txt"); List<Person> persons = reader.read(); List<Person> persons = new ArrayList<>(); FlatFileWriter<Person> writer = new FlatFileWriter<>(Person.class, "data.txt"); writer.write(persons);