NPC Trading is a full-featured trading system plugin that allows you to create custom NPC traders for your server.
Set up item exchanges, configure rotating trade offers, and integrate seamlessly with HyCitizens to create immersive merchant NPCs.

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Commands: /npctrading (or /nt)
Quick Open: /nt {TraderName}

Features

Trading System

Create and manage Traders that offer item exchanges to players.

Each Trader supports:

• Custom name
• Multiple trade offers
• Item rotation - Automatically cycle through different trades on a timer
• Configurable rotation intervals and displayed item count
• Integration with HyCitizens NPCs (optional)
• Direct trader access via command

Trade Offers

Each trade offer includes:

• Input item and quantity (what the player pays)
• Output item and quantity (what the player receives)
• Visual feedback for available/unavailable trades

Item Rotation

Keep trades fresh and encourage players to check back regularly:

• Enable/disable rotation per trader
• Set custom rotation intervals (in minutes)
• Control how many items display at once
• Automatic rotation with countdown timer

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In-Game Management UI

Use:

/npctrading (or /nt)

This opens the Trading UI, where you can:

• Create new Traders
• Edit existing Traders
• Manage trade offers
• Configure item rotation settings
• Link traders to HyCitizens NPCs
• Delete traders

No configuration files required to use the plugin.

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HyCitizens Integration

NPC Trading integrates seamlessly with HyCitizens (optional dependency):

• Link traders to any Citizen NPC
• NPCs are fully customizable through the HyCitizens menu (appearance, position, animations, equipment, etc.)
• Players interact with NPCs to open their trade menu
• Multiple NPCs can share the same trader
• Automatic binding system with timeout protection

Note: This plugin does not include an NPC spawner. You'll need HyCitizens or another NPC plugin to spawn the NPCs.

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Quick Access

Don't have an NPC set up yet? Use the quick command:

/nt {TraderName}

This opens the trader's menu directly without needing to interact with an NPC.

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Discord / Support

If you would like to join the community, suggest features, report bugs, or need some help, join the Discord community! https://discord.gg/Snqz9E58Dr

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Support NPC Trading

Want to support NPC Trading? You can donate at Ko-fi or share NPC Trading with your friends!

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Developer API

NPC Trading includes a full developer API for creating, editing, and managing traders programmatically.

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Getting the plugin instance:

NPCTradingPlugin plugin = NPCTradingPlugin.get();

TradersManager - The main entry point for all Trader operations:

TradersManager manager = plugin.getTradersManager();

Trader represents a single trader and all of its settings and trade offers.

Trader fields:

uuid (UUID) – unique trader identifier.
name (String) – displayed trader name.
trades (List<TradeOffer>) – list of all trade offers.
citizenIds (List<String>) – list of linked HyCitizens NPC IDs.
rotateItems (boolean) – whether items rotate on a timer.
rotationIntervalMinutes (int) – minutes between rotations.
displayedItemCount (int) – how many trades show at once when rotating.
lastRotationTime (long) – timestamp of last rotation.
currentRotationOffset (int) – current rotation position.

Creating a Trader

Create a new trader with a random UUID:

Trader trader = manager.createTrader("Blacksmith");

Create a trader with a specific UUID:

UUID uuid = UUID.randomUUID();
Trader trader = manager.createTrader(uuid, "Wandering Merchant");

This will add the trader to the registry and save it to storage.

Managing Trade Offers

TradeOffer represents a single exchange (input → output):

TradeOffer offer = new TradeOffer(
    "Resource_Iron_Ore",  // Input item ID
    10,                    // Input quantity
    "Resource_Iron_Ingot", // Output item ID
    5                      // Output quantity
);

Add a trade offer to a trader:

trader.addTrade(offer);
manager.saveTrader(trader);

Remove a trade by index:

trader.removeTrade(0); // Removes first trade
manager.saveTrader(trader);

Clear all trades:

trader.clearTrades();
manager.saveTrader(trader);

Get all trades:

List<TradeOffer> allTrades = trader.getTrades();

Get currently displayed trades (respects rotation):

List<TradeOffer> displayedTrades = trader.getDisplayedTrades();

Item Rotation Settings

Enable item rotation:

trader.setRotateItems(true);
trader.setRotationIntervalMinutes(5);  // Rotate every 5 minutes
trader.setDisplayedItemCount(3);       // Show 3 trades at a time
manager.saveTrader(trader);

Disable rotation:

trader.setRotateItems(false);
manager.saveTrader(trader);

Get rotation settings:

boolean rotating = trader.isRotateItems();
int interval = trader.getRotationIntervalMinutes();
int displayCount = trader.getDisplayedItemCount();
long lastRotation = trader.getLastRotationTime();
int offset = trader.getCurrentRotationOffset();

Linking NPCs (HyCitizens Integration)

Add a Citizen NPC to a trader:

trader.addCitizenId(citizenId);
manager.saveTrader(trader);

Remove a Citizen NPC:

trader.removeCitizenId(citizenId);
manager.saveTrader(trader);

Check if a Citizen is linked:

boolean isLinked = trader.hasCitizenId(citizenId);

Get all linked Citizens:

List<String> citizenIds = trader.getCitizenIds();

Find trader by Citizen ID:

Trader trader = manager.getTraderByCitizenId(citizenId);

Updating a Trader

After modifying a trader, save the changes:

trader.setName("Master Blacksmith");
trader.setRotationIntervalMinutes(10);
manager.saveTrader(trader);

Deleting a Trader

Remove a trader from the system:

boolean deleted = manager.deleteTrader(traderUuid);

This will remove the trader from memory and delete the saved data.

Getting Traders

Get trader by UUID:

Trader trader = manager.getTrader(uuid);

Get trader by name:

Trader trader = manager.getTraderByName("Blacksmith");

Get all traders:

Collection<Trader> traders = manager.getAllTraders();

Get all trader UUIDs:

Set<UUID> uuids = manager.getTraderUUIDs();

Check if trader exists:

boolean exists = manager.hasTrader(uuid);

Get trader count:

int count = manager.getTraderCount();

Trade Execution API

The TradeManager handles player transactions:

TradeManager tradeManager = plugin.getTradeManager();

Check if a player can afford a trade:

boolean canAfford = tradeManager.canAfford(playerRef, offer);

Get item count in player inventory:

int count = tradeManager.getItemCount(playerRef, "Resource_Iron_Ore");

Execute a trade:

boolean success = tradeManager.executeTrade(playerRef, offer);

This will:

• Verify the player has enough input items
• Remove input items from the player's inventory
• Add output items to the player's inventory
• Send confirmation messages
• Return true if successful, false otherwise

Opening Trade UI Programmatically

Open a trader's menu for a player:

plugin.getTradeUI().openTradeGUI(playerRef, store, trader);

NPC Binding System

The NPCBindManager handles the process of linking traders to NPCs:

NPCBindManager bindManager = plugin.getNPCBindManager();

Start a binding session (30-second timeout):

bindManager.startBinding(playerRef, trader);

Get active binding session:

NPCBindManager.BindingSession session = bindManager.getActiveSession(playerUuid);
if (session != null) {
    Trader trader = session.trader;
    PlayerRef player = session.playerRef;
}

Complete a binding:

bindManager.completeBinding(playerUuid);

Cancel a binding:

bindManager.cancelBinding(playerUuid);

Reload System

Reload all traders from storage:

manager.reload();

Credits

This plugin has been made possible by HyUI.