Util Create scrollable inventories

Hello,

I've created a dynamical scrollable inventory methods.
I'm not saying that this is the best, but it works.
I've actually not tried changing the 'rows', 'width' and 'skipPerPage', but I'm somewhat sure that it works. If not you can let me know.

'int page' starts at 0 and its displayed as page 1;
'String name' is the name of the inventory;
'List<ItemStack>' are ALL the items;
'ItemStack backButton' is the back button to go back, when 'null' there won't be any

This will automatically place an previous item and a next item

The code:

Code:java

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryAction;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
 
import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.List;
 
public class DynamicInventory {
 
    public static String NEXT = ChatColor.YELLOW + "Next";
    public static String PREVIOUS = ChatColor.YELLOW + "Previous";
    public static String BACK = ChatColor.YELLOW + "Back";
 
    private static ItemStack createStack(String displayName, Material material) {
        ItemStack is = new ItemStack(material);
 
        ItemMeta im = is.getItemMeta();
        im.setDisplayName(displayName);
        is.setItemMeta(im);
        return is;
    }
 
    public static void openDynamicScrollableInventory(Player player, int page, String name, List<ItemStack> items, @Nullable ItemStack backButton) {
        player.openInventory(getDynamicScrollableInventory(page, name, items, backButton));
    }
 
    public static Inventory getDynamicScrollableInventory(int page, String name, List<ItemStack> items, @Nullable ItemStack backButton) {
        int size = items.size();
 
        int rows = 3; //amount of rows
        int width = 7; //amount of items in a row
        int skipPerPage = 7; //amount of items skipped per page (width * rows to skip)
 
        //add max to GUI page
        if (size > rows * width) {
            page = Math.min(size / width - rows + (size % width == 0 ? 0 : 1), page);
        } else {
            page = 0;
        }
        page = Math.max(0, page); //set min to page
 
        size += (width - (size - 1) % width); //calculate square rectangle items
        size /= width; //get amount of rows
        if (size > rows) {
            size -= (size - rows); //set a max on 3 rows
        }
        size *= 9; //turn rows into slots
        size += 18; //add top and bottom row
 
        Inventory inv = Bukkit.createInventory(null, size, name + " (" + (page + 1) + ")");
 
        int a = page * skipPerPage; //amount to skip
 
        int slot = 9 + (9 - width) / 2;
        for (int index = a; index < a + width * rows && index < items.size(); index++) {
            if ((slot + 1) % 9 == 0) { //end of row, +2 to go to next row
                slot += (9 - width);
            }
            if (slot >= size - 9) { //end of items
                break;
            }
            inv.setItem(slot, items.get(index)); //add item
            slot++; //next slot
        }
 
        if (backButton != null) {
            inv.setItem(size / 18 * 9 + 8, backButton);
        }
 
        if ((page + rows) * width < items.size()) { //if not all items could be displayed, add next 'button'
            inv.setItem(size - 1, createStack(NEXT, Material.HOPPER));
        }
        if (page != 0) { //if not at page 0 (1 as display) add previous 'button'
            inv.setItem(8, createStack(PREVIOUS, Material.FERN));
        }
        return inv;
    }
 
    public static class ClickEvent implements Listener {//todo register class
 
        @EventHandler
        public void dynamicInventoryClick(InventoryClickEvent e) {
            Player player = (Player) e.getWhoClicked();
            Inventory inv = e.getInventory();
            String invTitle = e.getView().getTitle();
 
            if (e.getRawSlot() > inv.getSize()) {
                return;
            }
 
            ItemStack item = e.getCurrentItem();
            if (item == null) {
                return;
            }
 
            ItemMeta meta = item.getItemMeta();
            if (meta == null) {
                return;
            }
            if (!meta.hasDisplayName()) {
                return;
            }
 
            if (invTitle.startsWith("Your inventory name ")) {
                String pageNumber = invTitle.replace("Your inventory name ", "").replace("(", "").replace(")", "");
                if (meta.getDisplayName().equals(NEXT)) {
                    e.setCancelled(true);
                    //todo set your inventory
                    openDynamicScrollableInventory(player, Integer.parseInt(pageNumber), "Your inventory name ", new ArrayList<>()/*your items*/, createStack(BACK, Material.BARRIER));
                }
 
                if (meta.getDisplayName().equals(PREVIOUS)) {
                    e.setCancelled(true);
                    //todo set your inventory
                    openDynamicScrollableInventory(player, Integer.parseInt(pageNumber) - 2, "Your inventory name ", new ArrayList<>()/*your items*/, createStack(BACK, Material.BARRIER));
                }
 
                //back button
                if (item.getType().equals(Material.BARRIER)) {
                    if (meta.getDisplayName().equals(BACK)) {
                        e.setCancelled(true);
                        if (e.getAction().equals(InventoryAction.PICKUP_HALF)) {//right lick
                            //todo do something when the player right clicks
                        } else if (e.getAction().equals(InventoryAction.PICKUP_ALL)) {//left click
                            //todo do something when the player left clicks
                        } else if (e.getAction().equals(InventoryAction.CLONE_STACK) || e.getAction().equals(InventoryAction.UNKNOWN)) {//middle click
                            //todo do something when the player middle clicks (InventoryAction.UNKNOWN added for when the player has remapped his button to something else (like the button 'F'))
                        }
                        return;
                    }
                }
            }
        }
 
    }
}
 
 

 

@The_Spaceman
You accidentally typed "rivate" instead of "private" as the access modifier for the "createStack" method.

Some feedback:
1. I'd probably type all of this in 1 file, with the InventoryClickEvent being in a static class inside the upper class. (And make it so that it won't interfere with another InventoryClickEvent (at least to some extend, as the user can edit it themselves))
2. I'd also like this better if it included the imports for the file.
3. This is a minor thing but, a reminder that people still need to register the InventoryClickEvent.

 

Thanks for your feedback, I've put it all there