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. 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. An additional isClientRequest() convenience method returns the inverse.

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 via setNewSlot(byte) — changing this redirects which slot becomes active.
• serverRequest — true if initiated by the server, false if initiated by the client (player input). Also accessible as isClientRequest().

Fired By

• InventoryPacketHandler (lines 357, 415) via store.invoke(ref, event) — ECS dispatch when active hotbar slot changes (two call sites — server-request and client-request).

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 — Also dispatched from InventoryPacketHandler, related to inventory manipulation.