How do I change this line of code to make it fit with an ArrayList instead of a regular array?

Here's my code:

import java.util.ArrayList;

public class Checkout { private int size; private int amount; private int sum; private double taxRate; private ArrayList dessertItems; public Checkout() { size = 100; amount = 0; sum = 0; dessertItems = new ArrayList (); taxRate = DessertShoppe.TAX_RATE; } public void enterItem(DessertItem item) { dessertItems.add (item); amount++; } public int numberOfItems() { return amount; } public int totalCost() { sum = 0; for (int i = 0 ; i < amount ; i++) { sum += dessertItems[i].getCost (); } return sum; } public int totalTax() { return (int) (Math.round(this.totalCost() * taxRate / 100)); } public void clear() { for (DessertItem item : dessertItems) { item = null; } amount = 0; sum = 0; } public String toString() { String receipt = "Thank You!"; receipt += DessertShoppe.STORE_NAME + " "; receipt += "Purchased: "; String totalPay = DessertShoppe.cents2dollarsAndCents(totalCost() + totalTax()); if (totalPay.length() > DessertShoppe.COST_WIDTH) { totalPay = totalPay.substring(0, DessertShoppe.COST_WIDTH); } receipt += "$" + totalPay; return receipt; } }

This is the error code I get for the bolded line of code:

The type of the expression must be an array type but it resolved to ArrayList