SetPreferences.java

import java.util.prefs.*;
public class SetPreferences {
  public static String USAGE =
    "Usage: java SetPreferences <class> <pref> <val>";
  public static void main(String[] args) throws ClassNotFoundException {
    if (args.length!=3) {
      System.err.println(USAGE);
      System.exit(1);
    }
    Preferences prefs =
      Preferences.userNodeForPackage(Class.forName(args[0]));
    String oldVal = prefs.get(args[1],null);
    if (oldVal!=null) {
      System.out.println("Ancienne valeur : " + oldVal);
    } else {
      System.out.println("Ancienne valeur vide");
    }
    prefs.put(args[1],args[2]);
    System.out.println("La valeur de " + args[1] +
               " est maintenant : " + args[2]);
  }
}