IMPL_EXAMPLES.md

Examples on how to implement methods and events

Implementing methods

Sometimes it's easy, as Nukkit has the same method as Spigot.

    @Override
    public int broadcastMessage(String message) {
        return nukkit.broadcastMessage(message);
    }

Sometimes it's a bit more work:

    @Override
    public void savePlayers() {
        nukkit.getOnlinePlayers().values().forEach(cn.nukkit.Player::save);
    }

Sometimes we need some ugly code that might break in the future, so it's a good idea to add a little check. You can use the Pokkit.assertion(boolean, String) method for this:

    @Override
    public void setDefaultGameMode(GameMode gameMode) {
        // See nukkit.getDefaultGamemode() for setting name
        nukkit.setPropertyInt("gamemode", PokkitGameMode.toNukkit(gameMode));
        Pokkit.assertion(getDefaultGameMode() == gameMode, "Failed to set game mode");
    }

Sometimes you want to implement one method in a class, but are not interested in implementing the other methods in the class. In this case, don't let the code fail silently! This will only cause situations that are very hard to debug. So don't write return null; // TODO. Instead, use throw Pokkit.unsupported(). This method creates a nice error message.

For example:

    @Override
    public boolean useExactLoginLocation() {
        throw Pokkit.unsupported();
    }

Sometimes Nukkit simply doesn't support a feature. In this case, we have to be clever. Keep in mind that the goal of Pokkit is to get Bukkit plugins working. We have to look at each method on a case-by-case basis.

For unimportant stuff, you can simply let the method silently fail. For example, a previous version of Pokkit would simply do nothing if a Bukkit plugin tried to spawn a particle. Particles are usually just fluff; not throwing an error at least means that the rest of the Bukkit plugin can still keep working.

In the case of chat, I decided to send the message anyway, and simply leave out links, tooltips and everything else that Pocket Edition doesn't understand.

    @Override
    public void broadcast(BaseComponent component) {
        broadcastMessage(component.toLegacyText());
    }

Sometimes, you have no choice but to break plugins. Imagine that Nukkit would not have multiworld support; then how would you implement server.createWorld()? In that case, "implementing" the method using throw Pokkit.unsupported() may be the best option after all, as any multiworld plugin would break anyways. Pokkit.unsupported() at least provides a clear error message.

In reality, Nukkit does provide multiworld support. However, it cannot handle all possible Bukkit configurations (like a Nether world). In this case, I have decided to let the implementation of server.createWorld throw an error if Nukkit can't handle the given settings. Otherwise, the world is created normally.

 @Override
    public World createWorld(WorldCreator creator) {
        World alreadyLoaded = this.getWorld(creator.name());
        if (alreadyLoaded != null) {
            return alreadyLoaded;
        }

        if (creator.environment() != Environment.NORMAL) {
            throw new IllegalArgumentException("No Nether or End support yet");
        }

        // ... more checks here

        if (!nukkit.generateLevel(creator.name(), creator.seed(), PokkitWorldType.toNukkit(creator.type()), options)) {
            throw new RuntimeException("Failed to create world " + creator.name());
        }
        World world = this.getWorld(creator.name());
        Pokkit.assertion(world != null, "World was still null");
        return world;
    }

If you're wondering what the best implementation of a particular method would be, do not hesitate to contact us.

Implementing events

Events are implemented in a PokkitService. Take a look at this package. PokkitServices are registered in the Pokkit class.