bug

[loqqin]

Expected behavior

Items should not be removed

Observed/Actual behavior

Items are removed

Steps/models to reproduce

In the PlayerInteractEvent listener, you need to update the item in the player's hand, and in the BlockPlaceEvent listener, you need to cancel the event. Since the block isn't being placed, the item shouldn't be removed, but it is being removed.

Plugin and Datapack List

none

Paper version

latest 26.1.2

Other

https://youtu.be/yBz6xdmOukU

[electronicboy]

Provide reproduction code; ultimatly, events hook into game logic, and the game logic expects certain things to occur, so certain operations inside of events are often just not safe, mojang doesn't expect stuff like the item in the players hand to change and so isn't going to recheck the inventory

[loqqin]

public final class TestPlugin extends JavaPlugin implements Listener {

    @Override
    public void onEnable() {
        this.getServer().getPluginManager().registerEvents(this, this);
    }

    @EventHandler
    public void interact(PlayerInteractEvent event) {
        Player player = event.getPlayer();
        PlayerInventory inventory = player.getInventory();
        ItemStack itemInMainHand = inventory.getItemInMainHand();
        player.getInventory().setItemInMainHand(itemInMainHand);
    }

    @EventHandler
    public void place(BlockPlaceEvent event) {
        event.setCancelled(true);
    }
}

[electronicboy]

Yea, as said, modifying the item in the players hand is generally going to desync the servers logic, it's not viable or tenable to track what weird interactions people are doing with inventories inside of those events; This is a quirky area but really works as expected