import java.io.*;
import javax.swing.*;

class WriteDataFile2
{
    public static void main(String[] args)  throws IOException
    {
        String fname = JOptionPane.showInputDialog(null,"Enter file name");
        FileOutputStream myStream = new FileOutputStream(fname);
        DataOutputStream myDataStream = new DataOutputStream(myStream);

        for (int i=0;i<30;i++) {
           double x = Math.random();
           myDataStream.writeDouble(x);
          }
        myDataStream.close();
        System.exit(0);
    }
}