Non-config YML methods.

public class Example extends JavaPlugin {

    //                  Copy from here...

    public static FileConfiguration userdata = null;
    private static File userdataConfigFile = null;

    // You can rename the methods to anything you like. Userdata is just what I call it.
    // Also, in onEnable(), use loadUserdata() and to save it, use saveUserdata(). Simple enough.

    public void reloadUserdata() {
        if (userdataConfigFile == null) {
        userdataConfigFile = new File(getDataFolder(), "userdata.yml");
        }
        userdata = YamlConfiguration.loadConfiguration(userdataConfigFile);
        InputStream defConfigStream = getResource("userdata.yml");
        if (defConfigStream != null) {
            YamlConfiguration defConfig = YamlConfiguration.loadConfiguration(defConfigStream);
            userdata.setDefaults(defConfig);
        }
    }

    public void loadUserdata(){
        userdata = getUserdata();
        userdata.options().copyDefaults(true);
        saveUserdata();
    }

    public FileConfiguration getUserdata() {
        if (userdata == null) {reloadUserdata();}
        return userdata;
    }

    public static void saveUserdata() {
        if (userdata == null || userdataConfigFile == null) {
        return;
        }
        try {
            userdata.save(userdataConfigFile);
        } catch (IOException ex) {
            Util.sendPluginInfo("Could not save config to " + userdataConfigFile.getName() + ex);
        }
    }

    //                  ...To here!

}