Saving variable state in between sessions?

Question

So I'm in the process of developing a Java IRC bot as a bit of a side project for a friend of mine, and while development is going well, I'm a little unsure as how to save the current state of certain variables in between sessions. It doesn't have a GUI, so I didn't think that it would be too complex, but my searching efforts have been futile thus far.

Thanks.

Please narrow this question down, unless the answer you want is something like this: "Write the values to a file in the file-system. On start-up check if the well known file (in the previous sentence) exists, if it does; then load the values from that file. Otherwise, set the values to defaults." — Elliott Frisch, May 12 '14 at 20:18
As asked, the answer is in the question: Q. How to save the state between sessions? A. Save the state between sessions. — David Conrad, May 12 '14 at 20:35
https://stackoverflow.com/questions/3784657/what-is-the-best-way-to-save-user-settings-in-java-application — Troyseph, Nov 13 '17 at 20:44

score 0 · Answer 1 · answered May 23 '14 at 11:54

It will depend on the sort of variables you want to keep, but all methods will require you to write some sort data to a file.

If you only need to keep a handful of variables, you could consider implementing a .config file that could be a simple delimited text file.

If it's an entire object that you want to keep track of, say, a player in an irc game, one option you have is to parse the object into JSON, and save it to a textfile, for reading later. You can use Gson for this

example for a 'player' object:

public String savePlayer(String playerName){
    Gson gsonPretty = new GsonBuilder().setPrettyPrinting().create();
    String playerFile = System.getProperty("user.dir")+"\\players\\"+playerName;
    String jsonplayers = gsonPretty.toJson(players.get(playerName));
    try{
        FileWriter writer = new FileWriter(playerFile+".json");
        writer.write(jsonplayers);
        writer.close();
        return "Player file saved successfully!";

    }catch(Exception e){
        e.printStackTrace();
    }
    return "Something went wrong";
}

you can then create a load method that either has the file name hard coded, or a string input to determine which file to load, and use something like:

playerFromJson = gson.fromJson(jsonString, Player.class);

to use that object in the code

Saving variable state in between sessions?

1 Answers1