Add an action

First of all

You should see how create a new item if you do not have read it.

Types of Actions

There is 3 types of actions :

• LEFT_CLICK

• RIGHT_CLICK

• MIDDLE_CLICK

These actions allow you to add an effect when one of these action is used on your items.

Create a new action

GuiItem myItem() {
    GuiItem item = new GuiItem(Material.MATERIAL)
        .setAction(ItemActions.LEFT_CLICK,
            (player, plugin) {
                //here the plugin == null because we didn't set it in constructor
                Bukkit.getConsoleSender().sendMessage("Player " +
                player.getDisplayName() +
                " clicked on my item !");
            }
        );
    
    return item;
}

Pay attention, when you use your plugin in an action, you have to cast it because plugin argument is a JavaPlugin and not your plugin directly.