3. Slot Iterators

Slot Iterators are an easy way to iterate through the slots of an inventory. You can iterate horizontally or vertically.

Create an Iterator

To create an iterator, use this method from the class InventoryContents:

newIterator(SlotIterator.Type type, int startRow, int startColumn)

But it will just create a new iterator without saving it anywhere, it can be useful in some cases, but if you want to save your iterator to the inventory, use this method instead:

newIterator(String id, SlotIterator.Type type, int startRow, int startColumn)

You can put anything you want into this id, you will only use it to get and save the iterator.

Get an Iterator

To get a previously saved iterator, use iterator(String) with the id of your iterator, if an iterator with this id exists, it will return it inside an Optional, else, it will return an empty Optional. (Look at java Optional for further informations).

Use an Iterator

When you have your iterator, you now probably want to use it. Use the set(ClickableItem) method to set an item at the current position of the iterator.

Use next() to go to the next slot, if the type is HORIZONTAL, it will go one column forward, else if it is VERTICAL, it will go one row forward. The previous() method does the same thing, but it goes to one column/row backward.

You can use the get() method to get the item on the current position, this method also returns an Optional.

The row() and the column() methods return the actual position of the iterator. The row(int) and the column(int) methods define the position of the iterator.

The ended() method returns true if the iterator is at the last slot of the inventory, and else if it isn't.

You can allow the iterator to override existing items by calling the allowOverride(boolean) method, the default value is true.

Finally, the blacklist(int row, int column) method lets you blacklist a slot to skip it automatically (it will not skip the last slot).

Example

@Override
public void init(Player player, InventoryContents contents) {
    contents.newIterator("test", SlotIterator.Type.HORIZONTAL, 1, 1);
}

@Override
public void update(Player player, InventoryContents contents) {
    int state = contents.property("state", 0);
    contents.setProperty("state", state + 1);

    if(state % 5 != 0)
        return;

    SlotIterator iter = contents.iterator("test").get();

    if(iter.column() >= 7)
        return;

    iter.next();
    iter.set(ClickableItem.empty(new ItemStack(Material.WOOL, 1, (short) iter.column())));
}

(The state thing is to update our items only every 5 ticks instead of every tick)

And this is the result, when applied to a basic chest inventory with 3 rows: