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();
}
}