How to Lock item position in player's inventory?

How?
Player cannot change inventory item position.
please tell me.
thank you for answering.

What do you mean? Please describe more.

Handle InventoryTransactionEvent. If one of the transactions involves that certain slot, cancel event.

I personally recommend @PEMapModder 's theory but here is something you could also use...

PHP:

    public function onHeld(PlayerItemHeldEvent $event){
        $cfg = $this->getConfig();
        $player = $event->getPlayer();
        $hidetask = new PlayerHideTask($this, $player);
        $item = $event->getItem()->getId();
            switch($item){
                case $cfg->get("HidePlayers-Item"):
                    $this->task = $this->getServer()->getScheduler()->scheduleRepeatingTask($hidetask, 20);
                    $player->sendPopup(TextFormat::YELLOW . $cfg->get("HidePlayer-Message"));
                    $event->setCancelled(true);
                    break;
                case $cfg->get("ShowPlayers-Item"):
                    $this->getServer()->getScheduler()->cancelTask($this->task->getTaskId());
                    foreach ($this->getServer()->getOnlinePlayers() as $onl){
                        $player->showPlayer($onl);
                        $player->sendPopup(TextFormat::GREEN . $cfg->get("ShowPlayer-Message"));
                        $event->setCancelled(true);
                        }
                    break;
        }
    }
}


Code:

$event->setCancelled(true);

Cancels the 'PlayerItemHeldEvent $event' so the item get's placed back to where it was in the Inventory.

Sorry, lock hotbar items.
How to write this?

You don't have to hold an item to move it.

Yes.but, i want to this.