import java.io.FileOutputStream;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Properties;
import java.util.Vector;

public class Main {
  public static void main(String[] args) throws Exception {
    SortedProperties sp = new SortedProperties();
    sp.put("B", "value B");
    sp.put("C", "value C");
    sp.put("A", "value A");
    sp.put("D", "value D");
    FileOutputStream fos = new FileOutputStream("sp.props");
    sp.store(fos, "sorted props");
  }
}
class SortedProperties extends Properties {
  public Enumeration keys() {
    Enumeration keysEnum = super.keys();
    Vector<String> keyList = new Vector<String>();
    while (keysEnum.hasMoreElements()) {
      keyList.add((String) keysEnum.nextElement());
    }
    Collections.sort(keyList);
    return keyList.elements();
  }
}