Example - Show particles at a player's location

Say we wanted to have a command that displayed particles at a player's location. We will use the following command structure:

/showparticle <particle>

With this, we can simply spawn the particle using the World.spawnParticle(Particle, Location, int) method:

LinkedHashMap<String, Argument> arguments = new LinkedHashMap<>();
arguments.put("particle", new ParticleArgument());

new CommandAPICommand("showparticle")
    .withArguments(arguments)
    .executesPlayer((player, args) -> {
        player.getWorld().spawnParticle((Particle) args[0], player.getLocation(), 1);
    })
    .register();