SE450: Horstmann Chapter 5: Formatting Invoices

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

package horstmann.ch05_invoice;
/**
   This interface describes the tasks that an invoice
   formatter needs to carry out.
 */
public interface InvoiceFormatter
{
  /**
      Formats the header of the invoice.
      @return the invoice header
   */
  String formatHeader();

  /**
      Formats a line item of the invoice.
      @return the formatted line item
   */
  String formatLineItem(LineItem item);

  /**
      Formats the footer of the invoice.
      @return the invoice footer
   */
  String formatFooter();
}

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

package horstmann.ch05_invoice;
/**
   A simple invoice formatter.
 */
public class SimpleFormatter implements InvoiceFormatter
{
  public String formatHeader()
  {
    total = 0;
    return "     I N V O I C E\n\n\n";
  }

  public String formatLineItem(LineItem item)
  {
    total += item.getPrice();
    return (String.format(
        "%s: $%.2f\n",item.toString(),item.getPrice()));
  }

  public String formatFooter()
  {
    return (String.format("\n\nTOTAL DUE: $%.2f\n", total));
  }

  private double total;
}

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

package horstmann.ch05_invoice;
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.event.ChangeListener;

/**
   A program that tests the invoice classes.
 */
public class InvoiceTester
{
  public static void main(String[] args)
  {
    final Invoice invoice = new Invoice();
    final InvoiceFormatter formatter = new SimpleFormatter();

    // This text area will contain the formatted invoice
    final JTextArea textArea = new JTextArea(20, 40);

    // When the invoice changes, update the text area
    ChangeListener listener = event -> textArea.setText(invoice.format(formatter));
    invoice.addChangeListener(listener);

    // Add line items to a combo box
    final JComboBox<LineItem> combo = new JComboBox<>();
    Product hammer = new Product("Hammer", 19.95);
    Product nails = new Product("Assorted nails", 9.95);
    combo.addItem(hammer);
    Bundle bundle = new Bundle();
    bundle.add(hammer);
    bundle.add(nails);
    combo.addItem(new DiscountedItem(bundle, 10));

    // Make a button for adding the currently selected
    // item to the invoice
    JButton addButton = new JButton("Add");
    addButton.addActionListener(event -> {
      LineItem item = (LineItem) combo.getSelectedItem();
      invoice.addItem(item);
    });

    // Put the combo box and the add button into a panel
    JPanel panel = new JPanel();
    panel.add(combo);
    panel.add(addButton);

    // Add the text area and panel to the content pane
    JFrame frame = new JFrame();
    frame.add(new JScrollPane(textArea),
        BorderLayout.CENTER);
    frame.add(panel, BorderLayout.SOUTH);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
  }
}