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How to avoid casting when accessing subclass variables from ArrayList of type superclass

public void heal() {
    HealingItem hItem = null;
    
    Iterator<Item> it = getInventory().show_inventory().iterator();
    while (it.hasNext()) {
        if (it.next().getHealing_item() == true) {
            hItem = (HealingItem) it.next();
        }
    }
}

I have a parent class Item, and a subclass HealingItem which extends that – for this method I want the player to be able to only access the HealingItem’s in the ArrayList of type Item.

Is there a more efficient method of performing this action which perhaps doesn’t involve continually casting for these types of issues, or is it even my design which may be faulty?

Thanks

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Answer

Unfortunately, in Java you’re stuck with the “ceremony.” To fix your example per the discussion:

public void heal() {
    Iterator<Item> it = getInventory().show_inventory().iterator();

    while (it.hasNext()) {
        Item item = it.next();
        /*
         * item.getHealing_item() is true
         * implies item is instanceof HealingItem
         */
        if (item.getHealing_item()) {
            HealingItem hItem = (HealingItem) item;
            /*
             * Do something...
             */
        }
    }
}

In Java 11 you can reduce some of the ceremony with “var”:

public void heal() {
    var it = getInventory().show_inventory().iterator();

    while (it.hasNext()) {
        var item = it.next();

        if (item instanceof HealingItem) {
            var hItem = (HealingItem) item;
            /*
             * Do something...
             */
        }
    }
}

In Java 17 (preview feature as early as 14), you can use “enhanced” instanceof to combine the test with the cast:

public void heal() {
    var it = getInventory().show_inventory().iterator();

    while (it.hasNext()) {
        var item = it.next();

        if (item instanceof HealingItem hItem) {
            /*
             * Do something...
             */
        }
    }
}
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