Сохранение HashMaps в файл

Question

Я делаю бот, который имеет 2 HashMaps, которые мне нужно сериализовать и сохранить. Бот в основном присуждает очки за каждое отправленное сообщение, а затем на эти деньги вы можете построить город. Проблема в том, что я новичок в этом, и я не мог понять, как сериализовать эти HashMaps и где в коде должна происходить сериализация. Один из HashMaps имеет тип для точек, а другой содержит> для города. Любая помощь будет оценена.

//main class
import com.jagrosh.jdautilities.command.CommandClient;
import com.jagrosh.jdautilities.command.CommandClientBuilder;
import com.jagrosh.jdautilities.commons.waiter.EventWaiter;

import net.dv8tion.jda.core.AccountType;
import net.dv8tion.jda.core.JDA;
import net.dv8tion.jda.core.JDABuilder;
import net.dv8tion.jda.core.entities.Game;
import net.dv8tion.jda.core.hooks.ListenerAdapter;

public class DMain extends ListenerAdapter
{
    public static void main(String[] args) throws Exception
    {
        JDA jda = new JDABuilder(AccountType.BOT).setToken("token").build();

        CommandClientBuilder builder = new CommandClientBuilder();
        EventWaiter waiter = new EventWaiter();
        builder.setOwnerId("OwnerId");
        builder.setPrefix("$");
        builder.setHelpWord("help");
        builder.setGame(Game.listening("$help"));
        builder.addCommands(new PointsGetter(), new Build(waiter), new City(), new Upgrade(waiter),new Rename(waiter), new Info(), new Set());

        CommandClient client = builder.build();

        jda.addEventListener(client);
        jda.addEventListener(waiter);
        jda.addEventListener(new PointsAdder());

    }
}

//classes that pertain to the HashMaps I want to save
//class 1

import java.time.OffsetDateTime;
import java.util.HashMap;

import net.dv8tion.jda.core.entities.User;
import net.dv8tion.jda.core.events.message.MessageReceivedEvent;
import net.dv8tion.jda.core.hooks.ListenerAdapter;

public class PointsAdder extends ListenerAdapter
{   
    public static HashMap<User, Integer> bal = new HashMap<User, Integer>();
    private HashMap<User, OffsetDateTime> coolingDown = new HashMap<User, OffsetDateTime>();

    @Override
    public void onMessageReceived(MessageReceivedEvent e)
    {
        if(e.getAuthor().isBot())
            return;

        if(coolingDown.containsKey(e.getAuthor()))
        {
            if(e.getMessage().getCreationTime().isAfter(coolingDown.get(e.getAuthor()).plusSeconds(30)))
            {
                if(e.getMessage().getContentRaw().equalsIgnoreCase("$bal"))
                    return;

                if(bal.containsKey(e.getAuthor()))
                {
                    bal.put(e.getAuthor(), (bal.get(e.getAuthor()) + (1 + (int) (Math.random()*(100 - 90) + 90))));
                }
                else
                    bal.put(e.getAuthor(), 100);
                coolingDown.put(e.getAuthor(), e.getMessage().getCreationTime());
            }
            else
                return;
        }
        else
        {
            if(e.getMessage().getContentRaw().equalsIgnoreCase("$bal"))
                return;

            if(bal.containsKey(e.getAuthor()))
            {
                bal.put(e.getAuthor(), (bal.get(e.getAuthor()) + 1  + (int) (Math.random()*((100 - 90) + 90))));
            }
            else
                bal.put(e.getAuthor(), 100);
            coolingDown.put(e.getAuthor(), e.getMessage().getCreationTime());
        }
    }
}

//class 2
import java.util.ArrayList;
import java.util.HashMap;
import java.util.concurrent.TimeUnit;

import com.jagrosh.jdautilities.command.Command;
import com.jagrosh.jdautilities.command.CommandEvent;
import com.jagrosh.jdautilities.commons.waiter.EventWaiter;

import net.dv8tion.jda.core.entities.User;
import net.dv8tion.jda.core.events.message.guild.GuildMessageReceivedEvent;

public class Build extends Command 
{
    private final EventWaiter waiter;
    public static HashMap<User, ArrayList<Building>> city = new HashMap<User, ArrayList<Building>>();

    public Build(EventWaiter w)
    {
        super.name = "build";
        super.help = "Builds a new building in your city.";
        super.arguments = "(name your building after requested)";
        waiter = w;
    }

    @Override
    protected void execute(CommandEvent event) 
    {
        if(city.containsKey(event.getAuthor()))
        {
            if(PointsAdder.bal.containsKey(event.getAuthor()))
            {
                if(PointsAdder.bal.get(event.getAuthor()) >= 1000)
                {
                    event.reply("Ok! Now, give me the name you wish to call you building.");

                    waiter.waitForEvent(GuildMessageReceivedEvent.class, e -> e.getAuthor().equals(event.getAuthor()) && e.getChannel().equals(event.getChannel()), e -> {

                        city.get(event.getAuthor()).add(new Building(e.getMessage().getContentDisplay(), 100, 1));
                        PointsAdder.bal.put(e.getAuthor(), PointsAdder.bal.get(e.getAuthor())-1000);
                        event.reply(e.getAuthor().getAsMention() + " your building has been built.");
                    }, 30, TimeUnit.SECONDS, () -> event.reply("You did not give me a name. Try again."));
                }
                else
                    event.reply("You do not have sufficient funds to build a buidling.");
            }
            else
                event.reply("You do not have a balance yet.");
        }
        else
        {
            if(PointsAdder.bal.containsKey(event.getAuthor()))
            {
                if(PointsAdder.bal.get(event.getAuthor()) >= 1000)
                {
                    event.reply("Ok! Now, give me the name you wish to call you building.");

                    waiter.waitForEvent(GuildMessageReceivedEvent.class, e -> e.getAuthor().equals(event.getAuthor()) && e.getChannel().equals(event.getChannel()), e -> {

                        city.put(e.getAuthor(), new ArrayList<Building>());
                        city.get(event.getAuthor()).add(new Building(e.getMessage().getContentDisplay(), 100, 1));
                        PointsAdder.bal.put(e.getAuthor(), PointsAdder.bal.get(e.getAuthor())-1000);
                        event.reply(e.getAuthor().getAsMention() + " your building has been built.");
                    }, 30, TimeUnit.SECONDS, () -> event.reply("You did not give me a name. Try again."));
                }
                else
                    event.reply("You do not have sufficient funds to build a buidling.");
            }
            else
                event.reply("You do not have a balance yet.");
        }
    }

}

Я хочу иметь возможность перезагрузить бот и не потерять все данные игрока.

Answer 1

Если вы хотите сериализовать Hashmap, класс User должен реализовать интерфейс Serializeable, (class User implements Serializeable).

После этого вы можете сохранить и загрузить его в файл следующим образом:

спасти: save(map,"file");

нагрузка: map=(HashMap<User,Integer>)load("file"); if(map==null) map=new HashMap<>()

public void save(Object toSave,String filename) throws IOException{
    new File(filename).createNewFile()//create new file if it does not exist
    try(ObjectOutputStream oos=new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(filename)))){
        oos.writeObject(toSave);
    }
}
public Object load(String filename) throws IOException{
    try(ObjectInputStream ois=new ObjectInputStream(new BufferedInputStream(new FileInputStream(filename)))){
    return ois.readObject();
    }
}