simple method to check if the given items can fully fit in the given inventory

InventoryFit.java

    // Method copied from CraftInventory#addItem, but I removed the code that adds items to the inventory
    public static boolean canFit(Inventory inventory, ItemStack... items) {
        Validate.noNullElements(items, "Item cannot be null");

        ItemStack[] inventoryItems = getContents(inventory);

        for (ItemStack item : items) {
            while (true) {
                int firstPartial = firstPartial(inventoryItems, item);

                if (firstPartial == -1) {
                    int firstFree = inventory.firstEmpty();

                    if (firstFree == -1)
                        return false;

                    if (item.getAmount() > inventory.getMaxStackSize()) {
                        ItemStack stack = item.clone();
                        stack.setAmount(inventory.getMaxStackSize());
                        setItem(inventoryItems, firstFree, stack);
                        item.setAmount(item.getAmount() - inventory.getMaxStackSize());
                    }

                    setItem(inventoryItems, firstFree, item);
                    break;
                }

                ItemStack partialItem = inventoryItems[firstPartial];

                int amount = item.getAmount();
                int partialAmount = partialItem.getAmount();
                int maxAmount = partialItem.getMaxStackSize();

                if (amount + partialAmount <= maxAmount) {
                    partialItem.setAmount(amount + partialAmount);
                    setItem(inventoryItems, firstPartial, partialItem);
                    break;
                }

                partialItem.setAmount(maxAmount);
                setItem(inventoryItems, firstPartial, partialItem);
                item.setAmount(amount + partialAmount - maxAmount);
            }
        }

        return true;
    }

    private static ItemStack[] getContents(Inventory inventory) {
        ItemStack[] items = inventory.getContents();
        for (int i = 0; i < items.length; i++)
            items[i] = items[i] == null ? null : items[i].clone();
        return items;
    }

    private static int firstPartial(ItemStack[] items, ItemStack item) {
        for (int i = 0; i < items.length; i++) {
            ItemStack cItem = items[i];
            if (cItem != null && cItem.getAmount() < cItem.getMaxStackSize() && cItem.isSimilar(item))
                return i;
        }
        return -1;
    }

    private static void setItem(ItemStack[] items, int slot, ItemStack item) {
        items[slot] = item;
    }