1  import java.awt.event.ActionEvent;

  2  import java.awt.event.ActionListener;

  3  import javax.swing.JButton;

  4  import javax.swing.JFrame;

  5  import javax.swing.JLabel;

  6  import javax.swing.JPanel;

  7  import javax.swing.JTextField;

  8  

  9  public class InvestmentFrame extends JFrame

 10  {

 11     private JButton button;

 12     private JLabel label;

 13     private JPanel panel;

 14     private BankAccount account;

 15  

 16     private static final int FRAME_WIDTH = 400;

 17     private static final int FRAME_HEIGHT = 100;

 18  

 19     private static final double INTEREST_RATE = 10;

 20     private static final double INITIAL_BALANCE = 1000;

 21  

 22     public InvestmentFrame()

 23     {  

 24        account = new BankAccount(INITIAL_BALANCE);

 25  

 26        // Use instance variables for components 

 27        label = new JLabel("balance: " + account.getBalance());

 28  

 29        // Use helper methods 

 30        createButton();

 31        createPanel();

 32  

 33        setSize(FRAME_WIDTH, FRAME_HEIGHT);

 34     }

 35  

 36     private void createButton()

 37     {

 38        button = new JButton("Add Interest");

 39        ActionListener listener = new AddInterestListener();

 40        button.addActionListener(listener);

 41     }

 42  

 43     private void createPanel()

 44     {

 45        panel = new JPanel();

 46        panel.add(button);

 47        panel.add(label);      

 48        add(panel);

 49     }

 50  

 51     class AddInterestListener implements ActionListener

 52     {

 53        public void actionPerformed(ActionEvent event)

 54        {

 55           double interest = account.getBalance() * INTEREST_RATE / 100;

 56           account.deposit(interest);

 57           label.setText("balance: " + account.getBalance());

 58        }            

 59     }   

 60  }