//java.util.prefs.Preferences exportSubtree()
//It is storing all the of the nodes with key and values from the userRoot
//As per the spec. it is suppose to store key and values from the node where //this method is invoked.

//In the following program:
//N5.exportSubtree(fos);
//is invoked and expected to store key and values for N5 node and if any descendants.
//But it is storing key and values from user root.

import java.util.prefs.*;
import java.util.*;
import java.io.*;

public class ExportSubTree {
  
    public static void main(String[] args) {
        try{
           Preferences userRoot = Preferences.userRoot();
           
           Preferences N1 = userRoot.node("N1");
           N1.removeNode();
           N1 = userRoot.node("N1");
           N1.put("k1","v1");
          
           Preferences N2 = N1.node("N2");
           N2.put("k2","v2");
          
           Preferences N3 = N2.node("N3");
           N3.put("k3","v3");
           
           Preferences N4 = N2.node("N4");
           N4.put("k4","v4");
           
           Preferences N5 = N3.node("N5");
           N5.put("k5","v5");
           userRoot.flush();
           
           File systemFile = new File("user01.pfs");
           FileOutputStream fos = new FileOutputStream(systemFile);
          
           //exportSubtree
           N5.exportSubtree(fos);
           
           fos.close();
           System.out.println("user01.pfs output");
           System.out.println();
           RandomAccessFile raf = new RandomAccessFile("user01.pfs","r");
           String line = null;
           while ( (line = raf.readLine()) !=null) {
              System.out.println(line);
           }
         } catch(Exception e) {
            System.out.println("exception thrown " + e);
         }
    
   }
 
}
///////////////////////////////////output////////////////////////////////////////
H:\merlinTest\preferences\exportSubTree>java ExportSubTree
user01.pfs output

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE preferences SYSTEM 'http://java.sun.com/dtd/preferences.dtd&#39;>

<preferences>
  <root type="user">
    <node name="N1">
      <node name="N2">
        <node name="N3">
          <node name="N5">
            <node name="N1">
              <map>
                <entry key="k1" value="v1" />
              </map>
              <node name="N2">
                <map>
                  <entry key="k2" value="v2" />
                </map>
                <node name="N4">
                  <map>
                    <entry key="k4" value="v4" />
                  </map>
                </node>
                <node name="N3">
                  <map>
                    <entry key="k3" value="v3" />
                  </map>
                  <node name="N5">
                    <map>
                      <entry key="k5" value="v5" />
                    </map>
                  </node>
                </node>
              </node>
            </node>
          </node>
        </node>
      </node>
    </node>
  </root>
</preferences>