Java tutorial
import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.SeekableByteChannel; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.nio.file.StandardOpenOption; public class Test { public static void main(String[] args) throws IOException { Path path = Paths.get("/users.txt"); final String newLine = System.getProperty("line.separator"); try (SeekableByteChannel sbc = Files.newByteChannel(path, StandardOpenOption.APPEND)) { String output = newLine + "asdf" + newLine; ByteBuffer buffer = ByteBuffer.wrap(output.getBytes()); sbc.write(buffer); } } }