Java tutorial
import java.io.*; public class Main { public static void main(String[] args) { try { double d = 1.2345678; RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw"); raf.writeDouble(123.456789); // set the file pointer at 0 position raf.seek(0); System.out.println(raf.readDouble()); // set the file pointer at 0 position raf.seek(0); // write a double at the start raf.writeDouble(d); // set the file pointer at 0 position raf.seek(0); // read double System.out.println(raf.readDouble()); raf.close(); } catch (IOException ex) { ex.printStackTrace(); } } }