[FIXED] Updating Json file when String ist not present in list

Issue

I am coding a Discord Giveaway Bot with Java. I am saving all the details of the Giveaway to a JSON file. Now I want to read the entries list and if the Users ID is not in the list I want to add it and save the file.

Here is the Giveaway Class:

public class Giveaway {

    private String prize;
    private long time;
    private Integer winners;
    private List<String> entries;

    public Giveaway(String prize, Integer winners, long time, List<String> entries) {
        this.prize = prize;
        this.winners = winners;
        this.time = time;
        this.entries = entries;
    }

    public  Giveaway() {}

    public String getPrize() {
        return prize;
    }

    public void setPrize(String prize) {
        this.prize = prize;
    }

    public long getTime() {
        return time;
    }

    public void setTime(long time) {
        this.time = time;
    }

    public Integer getWinners() {
        return winners;
    }

    public void setWinners(Integer winners) {
        this.winners = winners;
    }

    public List<String> getEntries() {
        return entries;
    }

    public void setEntries(List<String> entries) {
        this.entries = entries;
    }

}

When the GW is created the JSON looks like this:

{
  "prize": "Discord Nitro",
  "time": 1641732935,
  "winners": 2,
  "entries": []
}

Then when the user clicks a button it should read the list look if the ID is in the list and if not add the id. But when I save the list the whole JSON file changes.

How I read it out and save it:

public class ButtonClick extends ListenerAdapter {

    private static Reader reader;

    private static Giveaway giveaway = new Giveaway();

    public void onButtonClick(ButtonClickEvent event) {
        event.deferEdit().queue();
        try {
            reader = Files.newBufferedReader(Path.of(GiveawayStats.getGiveawayStats().getAbsolutePath()));
        } catch (IOException e) {
            e.printStackTrace();
        }

        if (event.getButton().getId().equals("gwEnter")) {
            JsonParser parser = new JsonParser();
            JsonObject obj = parser.parse(reader).getAsJsonObject();
            JsonArray jsonEntries = obj.get("entries").getAsJsonArray();
            long time = obj.get("time").getAsLong();

            List<String> entries = new ArrayList<>();

            for (JsonElement entrie : jsonEntries) {
                entries.add(entrie.toString());
            }

            if (entries.contains(event.getMember().getId())) {
                event.getChannel().sendMessage("Already in!").queue();
            } else {
                entries.add(event.getUser().getId().strip());
                printToJson(entries);
            }
        }

        try {
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void printToJson(List<String> entries) {
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.setVersion(2.0);
        Gson gson = gsonBuilder.setPrettyPrinting().create();

        giveaway.setEntries(entries);

        try (Writer writer = new FileWriter(GiveawayStats.getGiveawayStats().getPath())) {
            gson.toJson(giveaway, writer);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

After the print so JSON the file looks like this:

{
  "time": 0,
  "entries": [
    "695629580014321747"
  ]
}

And when I click the Button again it looks like this:

{
  "time": 0,
  "entries": [
    "\"695629580014321747\"",
    "695629580014321747"
  ]
}

So why is my IF condition not working?

Solution

You are using entrie.toString() which gives you the string that is used for console output. You should be using entrie.getAsString() instead.

Furthermore, you are also using a lot of deprecated things with JsonParser which should be replaced. new JsonParser().parse(...) should be replaced by JsonParser.parseReader(...).

Above all that, it is highly recommended using a database for this kind of task. Something such as SQLite or Redis would be much better at handling concurrent changes and redundancy. Or at least, you should use a try-with-resources for your reader.

try (Reader reader = ...) {
  JsonElement json = JsonParser.parseReader(reader).getAsJsonObject();
  ...
}

Answered By - Minn