Custom items

Let's talk about real examples with item and custom NBT.

Simple data

Make simple items with NBT data.

Vouchers

Save voucher information inside item tag instead of comparing it with a large amount of items.

private Map<String, List<String>> vouchers = new HashMap();

public ItemStack setVoucher(ItemStack item, String voucherId) {
    return RtagItem.edit(item, tag -> {
        tag.set(voucherId, "voucher");
    });
}

public String getVoucherId(ItemStack item) {
    return new RtagItem(item).get("voucher");
}

public boolean handleVoucher(Player player, ItemStack item) {
    final String id = getVoucherId(item);
    if (id == null || !vouchers.containsKey(id)) {
        return false;
    }
    for (String cmd : vouchers.get(id)) {
        Bukkit.dispatchCommand(Bukkit.getConsoleSender(), cmd.replace("%player%", player.getName));
    }
    return true;
}

Number count

Count some number inside item tag.

public ItemStack addCount(ItemStack item, int amount) {
    return RtagItem.edit(item, tag -> {
        int i = tag.getOptional("myplugin", "count").or(0);
        i = i + amount;
        tag.set(i, "myplugin", "count");
    });
}

public int getCount(ItemStack item) {
    return new RtagItem(item).getOptional("myplugin", "count").or(0);
}

Item owner

Save item owner as custom tag.

public ItemStack setOwner(ItemStack item, OfflinePlayer player) {
    return RtagItem.edit(item, tag -> {
        tag.set(player.getName(), "owner", "name");
        tag.set(player.getUniqueId(), "owner", "uuid");
    });
}

public String getOwnerName(ItemStack item) {
    return new RtagItem(item).get("owner", "name");
}

public UUID getOwnerUuid(ItemStack item) {
    return new RtagItem(item).getOptional("owner", "uuid").asUuid();
}

Interactions

Modify item interactions using NBT data and event handling.

Save item on death

Let's make a custom tag like keepItem, set to true to save that item on death.

public ItemStack setKeepItem(ItemStack item, boolean value) {
    return RtagItem.edit(item, tag -> {
        tag.set(value, "keepItem");
    });
}

public boolean keepItem(ItemStack item) {
    return new RtagItem(item).getOptional("keepItem").or(false);
}

And handle it with PlayerDeathEvent and PlayerRespawnEvent.

private final Map<String, List<ItemStack>> savedItems = new HashMap<>();

@EventHandler
public void onDeath(PlayerDeathEvent e) {
    if (e.getKeepInventory()) {
        return;
    }

    List<ItemStack> matches = new ArrayList<>();
    e.getDrops().forEach(item -> {
        if (keepItem(item)) {
            matches.add(item);
        }
    });

    if (matches.isEmpty()) {
        return;
    }

    String name = e.getEntity().getName();
    if (savedItems.containsKey(name)) {
        savedItems.get(name).addAll(matches);
    } else {
        savedItems.put(name, matches);
    }

    e.getDrops().removeAll(matches);
}

@EventHandler
public void onRespawn(PlayerRespawnEvent e) {
    String name = e.getPlayer().getName();
    if (savedItems.containsKey(name)) {
        e.getPlayer().getInventory().addItem(savedItems.get(name).toArray(new ItemStack[0]));
        savedItems.remove(name);
    }
}