Controlling white space on output

Pass an indent string and whether or not to add newlines to the XMLSerializer constructor.

import org.jdom.*;
import org.jdom.output.XMLOutputter;
import java.math.BigInteger;
import java.io.*;


public class PrettyFibonacciJDOM {

  public static void main(String[] args) {

    Element root = new Element("Fibonacci_Numbers");

    BigInteger low  = BigInteger.ONE;
    BigInteger high = BigInteger.ONE;

    for (int i = 1; i <= 25; i++) {
      Element fibonacci = new Element("fibonacci");
      Attribute index = new Attribute("index", String.valueOf(i));
      fibonacci.setAttribute(index);
      fibonacci.setText(low.toString());
      root.addContent(fibonacci);

      BigInteger temp = high;
      high = high.add(low);
      low = temp;
    }

    Document doc = new Document(root);
    // serialize it into a file
    try {
      FileOutputStream out 
       = new FileOutputStream("pretty_fibonacci_jdom.xml");
      XMLOutputter serializer = new XMLOutputter("  ", true);
      serializer.output(doc, out);
      out.flush();
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}