Audiences

An audience, at its core, is a grouping of 0 or more viewers of some content. The concept of an audience is where Adventure makes its most clear break from other Minecraft platforms.

As an API, Audience is designed to be a universal interface for any player, command sender, console, or otherwise who can receive text, titles, boss bars, and other Minecraft media. This allows extending audiences to cover more than one individual receiver - possible “audiences” could include a team, server, world, or all players that satisfy some predicate (such as having a certain permission). The universal interface also allows reducing boilerplate by gracefully degrading functionality if it is not applicable. For instance, it does not make much sense to send a boss bar to a command sender, and you can’t send titles to Minecraft 1.7 clients.

You will normally get audience instances from one of the Platforms. The Adventure API includes two audience implementations itself: one that does not support any action (and thus does nothing). Audience.empty(), and one that forwards an action to each member in the audience, Audience.audience() and related methods, along with the ForwardingAudience that implements the forwarding logic for you.

Most users using will primarily use this API to show content created by other parts of the API.

A ForwardingAudience passes every action it receives on to other audiences. Its only abstract method is audiences(), so implementing it is enough to turn one of your own types into an audience:

public class GameTeam implements ForwardingAudience {
  private final List<GamePlayer> players = new ArrayList<>();

  // ...

  @Override
  public Iterable<? extends Audience> audiences() {
    return this.players;
  }
}

Everything that can be sent to an audience can now be sent to the whole team:

final GameTeam team = /* ... */;
team.sendMessage(Component.text("The game starts in 10 seconds!"));
team.playSound(Sound.sound(Key.key("block.note_block.pling"), Sound.Source.MASTER, 1F, 1F));

audiences() is called every time an action is forwarded, so members added to or removed from the backing collection are taken into account automatically.

If you do not need a type of your own, Audience.audience(Iterable<? extends Audience>), Audience.audience(Audience...), and the Audience.toAudience() collector can create a ForwardingAudience for you.

A forwarding audience made up of several members has no pointers of its own, so get(Identity.UUID) on the GameTeam above would return an empty Optional.

To wrap exactly one audience, implement ForwardingAudience.Single instead. It forwards pointers as well as actions:

public class GamePlayer implements ForwardingAudience.Single {
  private final Audience audience;
  private int score;

  public GamePlayer(final Audience audience) {
    this.audience = audience;
  }

  @Override
  public Audience audience() {
    return this.audience;
  }
}

This is especially useful in projects that support more than one platform. If common code only works with GamePlayer, each platform module can pass in the audience for its own player type. See Platforms for more information.

Many Audience methods are convenience overloads that end up calling a smaller set of methods. sendMessage(ComponentLike) calls sendMessage(Component) and showTitle(Title) calls sendTitlePart once for each part of the title. ForwardingAudience only overrides that smaller set, so that is also all you need to override to change what your audience does:

public class GameTeam implements ForwardingAudience {
  private static final Component PREFIX = Component.text("[Team] ");

  // ...

  @Override
  public void sendMessage(final Component message) {
    // Also applies to sendMessage(ComponentLike)
    ForwardingAudience.super.sendMessage(PREFIX.append(message));
  }
}

Audiences can also provide arbitrary information, such as display name or UUID. This is done using the pointer system.

Examples:

// get the uuid from an audience member, returning an Optional<UUID>
audience.get(Identity.UUID);

// get the display name, returning a default
audience.getOrDefault(Identity.DISPLAY_NAME, Component.text("no display name!"));