Grocery Item and Grocery List Example

public class GroceryItem
{
    // instance variables

    private String name;
    private double cost;        // could be float or int (if in cents)
    // Could also have quantity
    //      (e.g., you might have 1 "item" object for 5 apples).

    // Constructor

    public GroceryItem(String itemName, double itemCost)
    {
        this.name = itemName;
        this.cost = itemCost;
    }


    // Observer methods (one for each instance variable)

    public String getName()
    {
        return this.name;
    }

    public double getCost()
    {
        return this.cost;
    }

    // Should also have getQuantity if you have a quantity instance variable.

}

public class GroceryList
{
    // instance variables
    private ArrayList<GroceryItem> cart;

    // Constructor
    public GroceryList()
    {
        this.cart = new ArrayList<GroceryItem>();
    }


    // Methods
    public void addItem(GroceryItem item)     // Add item to the cart
    {
        this.cart.add(item);
    }


    public void printList()     // Print items, one per line
    {
        for ( GroceryItem item: this.cart )
        {
            System.out.println(item.getName() + ": " + item.getCost());
        }

        /* OR
        for ( int i = 0; i < this.cart.size(); i++ )
        {
            GroceryItem item = this.cart.get(i);
            System.out.println(item.getName() + ": " + item.getCost());
        }
        */
    }

    public int numItems()
    {
        return this.cart.size();
    }

    public int totalCost()      // Cost of buying all items in cart
    {
        double total = 0.0;

        for ( GroceryItem item: this.cart )
        {
            total = total + item.getCost();  // OR total += item.getCost();
        }

        /* OR
        for ( int i = 0; i < this.cart.size(); i++ )
        {
            GroceryItem item = this.cart.get(i);
            total = total + item.getCost();
        }
        */
    }

    public String cheapestItem()    // Returns name of cheapest item in list
    {
        if ( this.cart.isEmpty() == true )
            return "";

        // Assume the first item is the cheapest.
         GroceryItem cheapest = this.cart.get(0);

        // Look through all others to see if any are cheaper.
        for ( GroceryItem item: this.cart )
        {
            if ( item.getCost() < cheapest.getCost() )
                cheapest = item;
        }
        return cheapest.getName();

        /* OR
        // Assume the first item is the cheapest.
        int cheapIndex = 0;

        // Starting at the 2nd item, see if any others are cheaper.
        for ( int i = 1; i < this.cart.size(); i++ )
        {
            GroceryItem item = this.cart.get(i);
            if ( item.getCost() < this.cart.get(cheapIndex).getCost() )
                cheapIndex = i;
        }
        return this.cart.get(cheapIndex).getName();
        */

    }

    public int indexOfPriciestItem()
    {
        if ( this.cart.isEmpty() == true )
            return -1;

        // Assume the first item is the priciest.
        int priceyIndex = 0;

        // Starting at the 2nd item, see if any others are pricier.
        for ( int i = 1; i < this.cart.size(); i++ )
        {
            GroceryItem item = this.cart.get(i);
            if ( item.getCost() > this.cart.get(priceyIndex).getCost() )
                priceyIndex = i;
        }
        return priceyIndex;
    }
    
    /** Prints number of items in list, cheapest item, most expensive item
     *  (and its price), and the total cost of all the items.
     */
    public void printSummaryStats()
    {
        System.out.println("Number of items in list: " + this.numItems());

        GroceryItem cheapest = this.cart.get(this.cheapestItem);
        GroceryItem priciest = this.cart.get(this.indexOfPriciestItem());
        System.out.println("Cheapest item is: " + cheapest.getName());
        System.out.println("Priciest item is: " +
                priciest.getName() + " (" + priciest.getCost() + ")");

        System.out.println("Total cost of all items is: " + this.totalCost());
    }

    // Additional methods one could write:
    //  - A method that returns the index of the alphbetically first item
    //  - A method that returns the index of the alphbetically first item
    //      starting from a certain point, e.g.,
    //          alphaFirst(0)   returns the first from the whole list
    //          alphaFirst(5)   returns the first from the range (5 .. n-1)
    //  - A method that swaps two items in the list, e.g.,
    //          swap(0, 5)      swaps the items at indices 0 and 5
    //  - A method that finds the alphbetically first item in a range
    //      (i .. n-1) and moves that item to the beginning of the range, e.g.,
    //          sortHelper(5)  finds the alphabetically smallest item
    //                         from index 5 to the end of the list and
    //                         rearranges that part of the list in some
    //                         way so that the smallest item will be at
    //                         index 5.
    //  - A method that sorts the items in the grocery list alphabetically.

}