public class Main extends JavaPlugin implements Listener {
	public void onEnable() {
		getServer().getPluginManager().registerEvents(this, this);
	}

	public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
		if (label.equalsIgnoreCase("Test")) {
			Inventory inv = Bukkit.createInventory(null, 9, "Test GUI");
			ItemStack is = new ItemStack(Material.NETHER_STAR);
			ItemMeta im = is.getItemMeta();
			im.setDisplayName("a");
			is.setItemMeta(im);
			inv.setItem(4, is);
			((Player) sender).openInventory(inv);
		}
		if (label.equalsIgnoreCase("Test2")) {
			Inventory inv = Bukkit.createInventory(null, 9, "Test GUI2");
			((Player) sender).openInventory(inv);
		}
		return false;
	}

	@EventHandler
	public void onClick(InventoryClickEvent e) {
		if (e.getCurrentItem().getItemMeta().getDisplayName().equals("a")) {
			Inventory inv = Bukkit.createInventory(null, 9, "Test GUI2");
			((Player) e.getWhoClicked()).openInventory(inv);
		}
	}

	@EventHandler
	public void onClose(InventoryCloseEvent e) {
		for (int i = 0; i < e.getInventory().getSize(); i++)
			if (e.getInventory().getItem(i) != null)
				Bukkit.broadcastMessage(i + " : " + e.getInventory().getItem(i).getTypeId());
			else
				Bukkit.broadcastMessage(i + " : X");
	}
}