SwitchActiveSlotEvent

SwitchActiveSlotEvent

Package: com.hypixel.hytale.server.core.event.events.ecs Extends: CancellableEcsEvent Implements: ICancellableEcsEvent Cancellable: Yes

ECS event dispatched when the active hotbar slot changes. This fires for both client-initiated slot switches (player pressing hotbar keys) and server-initiated slot switches (programmatic changes). The serverRequest field distinguishes the two origins.

Cancelling this event prevents the active slot from changing. The newSlot field is mutable, allowing listeners to redirect the selection to a different slot.

Fields / Accessors

Field	Type	Accessor	Mutable	Nullable
inventorySectionId	int	getInventorySectionId()	No	No
previousSlot	int	getPreviousSlot()	No	No
newSlot	byte	getNewSlot()	Yes	No
serverRequest	boolean	isServerRequest()	No	No

• inventorySectionId — The inventory section being switched within (identifies the hotbar section).
• previousSlot — The slot index that was active before this switch.
• newSlot — The slot index being switched to. Mutable — changing this redirects which slot becomes active.
• serverRequest — true if this slot switch was initiated by the server, false if initiated by the client (player input).

Fired By

• InventoryPacketHandler (line 353) via store.invoke(ref, event) — ECS dispatch for server-initiated slot switch.
• InventoryPacketHandler (line 406) via store.invoke(ref, event) — ECS dispatch for client-initiated slot switch.

Listening

ECS events are handled by EntityEventSystem subclasses, not by getEventRegistry().register().

public class MySlotSwitchHandler extends EntityEventSystem<EntityStore, SwitchActiveSlotEvent> {
    @Override
    public Query<EntityStore> getQuery() {
        return MY_COMPONENT_TYPE;
    }

    @Override
    public void handle(int index, ArchetypeChunk<EntityStore> chunk,
                       Store<EntityStore> store, CommandBuffer<EntityStore> commandBuffer,
                       SwitchActiveSlotEvent event) {
        int previous = event.getPreviousSlot();
        byte newSlot = event.getNewSlot();
        boolean fromServer = event.isServerRequest();

        // Example: lock the active slot during a minigame
        if (isMinigameActive()) {
            event.setCancelled(true);
        }
    }
}

// Register in plugin setup():
getEntityStoreRegistry().registerSystem(new MySlotSwitchHandler());

Related Events

• DropItemEvent.PlayerRequest — Also dispatched from InventoryPacketHandler, fired when a player requests to drop an item from inventory.