Boss Bars

Constructing a Boss Bar

Boss Bars are composed of:

A component used for the title of the boss bar
A number from 0 to 1 used to determine how full the boss bar should be
A color, will be downsampled for clients <1.9
An overlay that determines the amount of visual segments on the boss bar

Examples:

private @Nullable BossBar activeBar;

public void showMyBossBar(final @NonNull Audience target) {
  final Component name = Component.text("Awesome BossBar");
  // Creates a red boss bar which has no progress and no notches
  final BossBar emptyBar = BossBar.bossBar(name, 0, BossBar.Color.RED, BossBar.Overlay.PROGRESS);
  // Creates a green boss bar which has 50% progress and 10 notches
  final BossBar halfBar = BossBar.bossBar(name, 0.5f, BossBar.Color.GREEN, BossBar.Overlay.NOTCHED_10);
  // etc..
  final BossBar fullBar = BossBar.bossBar(name, 1, BossBar.Color.BLUE, BossBar.Overlay.NOTCHED_20);

  // Send a bossbar to your audience
  target.showBossBar(fullBar);

  // Store it locally to be able to hide it manually later
  this.activeBar = fullBar;
}

public void hideActiveBossBar(final @NonNull Audience target) {
  target.hideBossBar(this.activeBar);
  this.activeBar = null;
}

Changing an active Boss Bar

Boss bars are mutable and listen for changes on their object, the in-game view will change automatically without having to manually refresh it!

Therefore, if this boss bar is currently active

final BossBar bossBar = BossBar.bossBar(Component.text("Cat counter"), 0, BossBar.Color.RED, BossBar.Overlay.PROGRESS);

and BossBar.name() with a component is called

final Component newText = Component.text("Duck counter");
bossBar.name(newText);

the boss bar will be updated automatically. The same thing goes for progress, color and overlay.