1  import java.awt.*;

  2  import java.awt.event.*;

  3  import javax.swing.*;

  4  import javax.swing.event.*;

  5  

  6  /**

  7     A program that tests the invoice classes.

  8  */

  9  public class InvoiceTester

 10  {

 11     public static void main(String[] args)

 12     {

 13        Invoice invoice = new Invoice();

 14        InvoiceFormatter formatter = new SimpleFormatter();

 15  

 16        // This text area will contain the formatted invoice

 17        JTextArea textArea = new JTextArea(20, 40);

 18  

 19        // When the invoice changes, update the text area

 20        invoice.addChangeListener(event ->

 21           textArea.setText(invoice.format(formatter)));

 22  

 23        // Add line items to a combo box

 24        JComboBox<LineItem> combo = new JComboBox<>();

 25        Product hammer = new Product("Hammer", 19.95);

 26        Product nails = new Product("Assorted nails", 9.95);

 27        combo.addItem(hammer);

 28        Bundle bundle = new Bundle();

 29        bundle.add(hammer);

 30        bundle.add(nails);

 31        combo.addItem(new DiscountedItem(bundle, 10));

 32  

 33        // Make a button for adding the currently selected

 34        // item to the invoice

 35        JButton addButton = new JButton("Add");

 36        addButton.addActionListener(event ->

 37           {

 38              LineItem item = combo.getItemAt(combo.getSelectedIndex());

 39              invoice.addItem(item);

 40           });

 41  

 42        // Put the combo box and the add button into a panel

 43        JPanel panel = new JPanel();

 44        panel.add(combo);

 45        panel.add(addButton);

 46  

 47        // Add the text area and panel to the frame

 48        JFrame frame = new JFrame();

 49        frame.add(new JScrollPane(textArea),

 50           BorderLayout.CENTER);

 51        frame.add(panel, BorderLayout.SOUTH);

 52        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

 53        frame.pack();

 54        frame.setVisible(true);

 55     }

 56  }