public class Main extends JavaPlugin implements Listener {

    public void onEnable() {
        Bukkit.getPluginManager().registerEvents(this, this);
    }

    public void onDisable() {

    }

    @EventHandler
    public void inventoryOpen(InventoryOpenEvent e) {
        e.getPlayer().sendMessage("You opened (name): " + e.getInventory().getName());
        e.getPlayer().sendMessage("You opened (title): " + e.getInventory().getName());
        e.getPlayer().sendMessage("You opened (type): " + e.getInventory().getType().toString());
    }
}