Java tutorial
import java.io.IOException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.nio.file.StandardOpenOption; public class Main { public static void main(String[] args) throws IOException { Path path = Paths.get("/users.txt"); byte[] contents = Files.readAllBytes(path); Path newPath = Paths.get("/newUsers.txt"); byte[] newContents = "aaa".getBytes(); Files.write(newPath, contents, StandardOpenOption.CREATE); Files.write(newPath, newContents, StandardOpenOption.APPEND); } }