How to add an item only if no other items exist with the same name in the arraylist?

How would I go about only inserting an item if the item does not have the same name as the other items in the arraylist within my insertUniqueItem() method?

    public void insertUniqueItem()
    {

    }

    public static void main(String[] args)
    {
        ShoppingCart sc = new ShoppingCart();
        Item a = new Item("Kraft Cheese", 4, ""Best Cheese in Town!"");
        Item b = new Item("Bottle of Water", 2.50, ""Refreshing Water!"");

        sc.insertItem(a);
        sc.insertItem(b);

        sc.printInvoice();
        sc.insertUniqueItem();

        sc.print();

        DecimalFormat df = new DecimalFormat("#.00");

        System.out.println("Total Price: $" + df.format(sc.getTotal()));
    }
}

Answer

You need to check if an item with the same name already exists in your list:

public void insertUniqueItem(Item item) {
    if(!contains(item)) {
        cart.add(item);
    }
}

private boolean contains(Item item) {
    for(Item i : cart) {
        if(i.getName().equals(item.getName())) {
           return true;
        }
    }
    return false;
}