save preferences

/*In this section you will learn that how a user can access the System preferences. Here we are going to make it easier to understand the step be step process by the complete example on this topic. If we consider the example it will display the preferences of the system as root type is system and due to none key value and node it display nothing in map*/
import java.util.prefs.*;
import java.io.IOException;

public class SavePrefs {
    public static void main(String[] args)
            throws IOException, BackingStoreException {
        Preferences root = Preferences.systemRoot();
        root.exportSubtree(System.out);
    }
}