public class ExampleBot {

  public static void main(String[] args) {
    String token = args[0];
    DiscordClient client = DiscordClient.create(token);
    GatewayDiscordClient gateway = client.login().block();

    gateway.on(MessageCreateEvent.class).subscribe(event -> {
      Message message = event.getMessage();
      if ("!ping".equals(message.getContent())) {
        MessageChannel channel = message.getChannel().block();
        channel.createMessage("Pong!").block();
      }
    });

    gateway.onDisconnect().block();
  }
}

public class ExampleBot {

  public static void main(String[] args) {
    String token = args[0];
    DiscordClient client = DiscordClient.create(token);

    client.login().flatMapMany(gateway -> gateway.on(MessageCreateEvent.class))
      .map(MessageCreateEvent::getMessage)
      .filter(message -> "!ping".equals(message.getContent()))
      .flatMap(Message::getChannel)
      .flatMap(channel -> channel.createMessage("Pong!"))
      .blockLast();
  }
}

public class ExampleBot {

    public static void main(String[] args) {
        String token = args[0];
        DiscordClient client = DiscordClient.create(token);

        client.withGateway(gateway -> {
            Publisher<?> pingPong = gateway.on(MessageCreateEvent.class, event ->
                    Mono.just(event.getMessage())
                            .filter(message -> "!ping".equals(message.getContent()))
                            .flatMap(Message::getChannel)
                            .flatMap(channel -> channel.createMessage("Pong!")));

            Publisher<?> onDisconnect = gateway.onDisconnect()
                    .doOnTerminate(() -> System.out.println("Disconnected!"));

            return Mono.when(pingPong, onDisconnect);
        }).block();
    }
}

GatewayDiscordClient client = DiscordClient.create(token)
  .gateway()
  .setEnabledIntents(IntentSet.nonPrivileged().and(IntentSet.of(Intent.MESSAGE_CONTENT)))
  .login()
  .block();

// IMAGE_URL = https://cdn.betterttv.net/emote/55028cd2135896936880fdd7/3x
// ANY_URL = https://www.youtube.com/watch?v=5zwY50-necw
MessageChannel channel = ...
EmbedCreateSpec.Builder builder = EmbedCreateSpec.builder();
builder.author("setAuthor", ANY_URL, IMAGE_URL);
builder.image(IMAGE_URL);
builder.title("setTitle/setUrl");
builder.url(ANY_URL);
builder.description("setDescription\n" +
      "big D: is setImage\n" +
      "small D: is setThumbnail\n" +
      "<-- setColor");
builder.addField("addField", "inline = true", true);
builder.addField("addFIeld", "inline = true", true);
builder.addField("addFile", "inline = false", false);
builder.thumbnail(IMAGE_URL);
builder.footer("setFooter --> setTimestamp", IMAGE_URL);
builder.timestamp(Instant.now());
channel.createMessage(builder.build()).block();

Guild guild = ...
Set<Member> roleMembers = new HashSet<>();

for (Member member : guild.getMembers().toIterable()) {
  for (Role role : member.getRoles().toIterable()) {
    if ("Developers".equalsIgnoreCase(role.getName())) {
      roleMembers.add(member);
      break;
    }
  }
}

return roleMembers;

Guild guild = ...
return guild.getMembers()
  .filterWhen(member -> member.getRoles()
    .map(Role::getName)
    .any("Developers"::equalsIgnoreCase));

public static final AudioPlayerManager PLAYER_MANAGER;

static {
  PLAYER_MANAGER = new DefaultAudioPlayerManager();
  // This is an optimization strategy that Discord4J can utilize to minimize allocations
  PLAYER_MANAGER.getConfiguration().setFrameBufferFactory(NonAllocatingAudioFrameBuffer::new);
  AudioSourceManagers.registerRemoteSources(PLAYER_MANAGER);
  AudioSourceManagers.registerLocalSource(PLAYER_MANAGER);
}

public class LavaPlayerAudioProvider extends AudioProvider {

  private final AudioPlayer player;
  private final MutableAudioFrame frame;

  public LavaPlayerAudioProvider(AudioPlayer player) {
    // Allocate a ByteBuffer for Discord4J's AudioProvider to hold audio data for Discord
    super(ByteBuffer.allocate(StandardAudioDataFormats.DISCORD_OPUS.maximumChunkSize()));
    // Set LavaPlayer's AudioFrame to use the same buffer as Discord4J's
    frame = new MutableAudioFrame();
    frame.setBuffer(getBuffer());
    this.player = player;
  }

  @Override
  public boolean provide() {
    // AudioPlayer writes audio data to the AudioFrame
    boolean didProvide = player.provide(frame);

    if (didProvide) {
      getBuffer().flip();
    }

    return didProvide;
  }
}

public class AudioTrackScheduler extends AudioEventAdapter {

  private final List<AudioTrack> queue;
  private final AudioPlayer player;

  public AudioTrackScheduler(AudioPlayer player) {
    // The queue may be modifed by different threads so guarantee memory safety
    // This does not, however, remove several race conditions currently present
    queue = Collections.synchronizedList(new LinkedList<>());
    this.player = player;
  }

  public List<AudioTrack> getQueue() {
    return queue;
  }

  public boolean play(AudioTrack track) {
    return play(track, false);
  }

  public boolean play(AudioTrack track, boolean force) {
    boolean playing = player.startTrack(track, !force);

    if (!playing) {
      queue.add(track);
    }

    return playing;
  }

  public boolean skip() {
    return !queue.isEmpty() && play(queue.remove(0), true);
  }

  @Override
  public void onTrackEnd(AudioPlayer player, AudioTrack track, AudioTrackEndReason endReason) {
    // Advance the player if the track completed naturally (FINISHED) or if the track cannot play (LOAD_FAILED)
    if (endReason.mayStartNext) {
      skip();
    }
  }
}

public class GuildAudioManager {

  private static final Map<Snowflake, GuildAudioManager> MANAGERS = new ConcurrentHashMap<>();

  public static GuildAudioManager of(Snowflake id) {
    return MANAGERS.computeIfAbsent(id, ignored -> new GuildAudioManager());
  }

  private final AudioPlayer player;
  private final AudioTrackScheduler scheduler;
  private final LavaPlayerAudioProvider provider;

  private GuildAudioManager() {
    player = PLAYER_MANAGER.createPlayer();
    scheduler = new AudioTrackScheduler(player);
    provider = new LavaPlayerAudioProvider(player);

    player.addListener(scheduler);
  }

  // getters
}

VoiceChannel channel = ...
AudioProvider provider = GuildAudioManager.of(channel.getGuildId()).getProvider();
VoiceConnection connection = channel.join(spec -> spec.setProvider(provider)).block();

// In the AudioLoadResultHandler, add AudioTrack instances to the AudioTrackScheduler (and send notifications to users)
PLAYER_MANAGER.loadItem("https://www.youtube.com/watch?v=dQw4w9WgXcQ", new AudioLoadResultHandler() { /* overrides */ })

VoiceChannel channel = ...
Mono<Void> onDisconnect = channel.join(spec -> { /* TODO Initialize */ })
  .flatMap(connection -> {
    // The bot itself has a VoiceState; 1 VoiceState signals bot is alone
    Publisher<Boolean> voiceStateCounter = channel.getVoiceStates()
      .count()
      .map(count -> 1L == count);

    // After 10 seconds, check if the bot is alone. This is useful if
    // the bot joined alone, but no one else joined since connecting
    Mono<Void> onDelay = Mono.delay(Duration.ofSeconds(10L))
      .filterWhen(ignored -> voiceStateCounter)
      .switchIfEmpty(Mono.never())
      .then();

    // As people join and leave `channel`, check if the bot is alone.
    // Note the first filter is not strictly necessary, but it does prevent many unnecessary cache calls
    Mono<Void> onEvent = channel.getClient().getEventDispatcher().on(VoiceStateUpdateEvent.class)
      .filter(event -> event.getOld().flatMap(VoiceState::getChannelId).map(channel.getId()::equals).orElse(false))
      .filterWhen(ignored -> voiceStateCounter)
      .next()
      .then();

    // Disconnect the bot if either onDelay or onEvent are completed!
    return Mono.first(onDelay, onEvent).then(connection.disconnect());
  });