New to Java

well i m developing a card game in java.
i would like to know for saving the game settings like the cards and variables of the game what backend should i use. i want the application to be fully platform independent and also dont want to use any proprietory s/w like ms access.

should i store it in a txt/dat file or is there any such compatible db; not talking abt full fledged server kinda dbms like oracle or sql server. just a basic dbms s/w for a small need like this.
thanx