get a list of user ids from a server

IDGrabber.java

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package com.jagrosh.idgrabber;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import javax.security.auth.login.LoginException;
import net.dv8tion.jda.core.AccountType;
import net.dv8tion.jda.core.JDABuilder;
import net.dv8tion.jda.core.MessageBuilder;
import net.dv8tion.jda.core.entities.Guild;
import net.dv8tion.jda.core.events.message.MessageReceivedEvent;
import net.dv8tion.jda.core.exceptions.RateLimitedException;
import net.dv8tion.jda.core.hooks.ListenerAdapter;

/**
 *
 * @author John Grosh ([email protected])
 */
public class IDGrabber extends ListenerAdapter {
    
    public static void main(String[] args) throws IOException, LoginException, IllegalArgumentException, RateLimitedException {
        new JDABuilder(AccountType.CLIENT).setToken(Files.readAllLines(Paths.get("config.txt")).get(0)).addListener(new IDGrabber()).buildAsync();
    }

    @Override
    public void onMessageReceived(MessageReceivedEvent event) {
        if(event.getAuthor().equals(event.getJDA().getSelfUser()) && event.getMessage().getContent().startsWith("self.ids"))
        {
            String id = event.getMessage().getContent().substring(8).trim();
            Guild guild = event.getJDA().getGuildById(id);
            if(guild==null)
                event.getChannel().sendMessage("No guild with id `"+id+"`").queue();
            else
            {
                StringBuilder builder = new StringBuilder(guild.getName()+" ("+guild.getId()+")\r\n---");
                guild.getMembers().forEach(m -> builder.append("\r\n").append(m.getUser().getId()).append(" ").append(m.getUser().getName()).append("#").append(m.getUser().getDiscriminator()));
                try {
                    Files.write(Paths.get("guild-ids-"+guild.getId()+".txt"), builder.toString().getBytes());
                    event.getChannel().sendFile(new File("guild-ids-"+guild.getId()+".txt"), new MessageBuilder().append("All user IDs from "+guild.getName()+":").build()).queue();
                } catch (IOException ex) {
                    event.getChannel().sendMessage("Failed to save+upload file").queue();
                }
            }
        }
    }
}

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