Suppose that class OrderList has a private attribute double cost[100] which hold the cost of all ordered items, and a private attributes int num_of_items which hold the number of items ordered. For example, if num_of_items is 5, then cost[0], cost[1], ..., cost[4] hold the cost of these 5 items. Implement the member function named total_cost which returns the total cost of this OrderList.

OrderList. java

public class OrderList { private double cost[]; private int num_of_items; public OrderList () { cost = new double[100]; } public double total_cost () { double total = 0; for (int i=0; i < num_of_items; i++) { total + = cost[i]; } return total; } }

Main. java

public class Main { public static void main (String[] args) { OrderList sample = new OrderList (); double totalCost = sample. total_cost (); } }

Explanation:

Firstly, define a class OrderList with two private attributes, cost and num_of_items (Line 1-3). In the constructor, initialize the cost attribute with a double type array with size 100. Next, create another method total_cost () to calculate the total cost of items (Line 9-15). To implement the total_cost member function, create an OrderList instance and use that instance to call the total_cost () and assign it to totalCost variable.