Java tutorial
import java.io.RandomAccessFile; public class Main { public static void main(String[] args) throws Exception { RandomAccessFile randomAccessFile = null; String line1 = "line\n"; String line2 = "asdf1234\n"; // read / write permissions randomAccessFile = new RandomAccessFile("yourFile.dat", "rw"); randomAccessFile.writeBytes(line1); randomAccessFile.writeBytes(line2); // Place the file pointer at the end of the first line randomAccessFile.seek(line1.length()); byte[] buffer = new byte[line2.length()]; randomAccessFile.read(buffer); System.out.println(new String(buffer)); randomAccessFile.close(); } }