SE450: Horstmann Chapter 5: Putting Patterns to Work

Invoice contains line items
Line item has description, price
Interface type LineItem
Product is a concrete class that implements this interface

file:horstmann/ch05_invoice/LineItem.java [source] [doc-public] [doc-private]

package horstmann.ch05_invoice;
/**
   A line item in an invoice.
 */
public interface LineItem
{
  /**
      Gets the price of this line item.
      @return the price
   */
  double getPrice();
  /**
      Gets the description of this line item.
      @return the description
   */
  String toString();
}

file:horstmann/ch05_invoice/Product.java [source] [doc-public] [doc-private]

package horstmann.ch05_invoice;
/**
   A product with a price and description.
 */
public class Product implements LineItem
{
  /**
      Constructs a product.
      @param description the description
      @param price the price
   */
  public Product(String description, double price)
  {
    this.description = description;
    this.price = price;
  }
  public double getPrice() { return price; }
  public String toString() { return description; }
  private String description;
  private double price;
}