import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class InvestmentFrame extends JFrame
{
   private JButton button;
   private JLabel label;
   private JPanel panel;
   private BankAccount account;

   private static final int FRAME_WIDTH = 400;
   private static final int FRAME_HEIGHT = 100;

   private static final double INTEREST_RATE = 10;
   private static final double INITIAL_BALANCE = 1000;

   public InvestmentFrame()
   {  
      account = new BankAccount(INITIAL_BALANCE);

      // Use instance variables for components 
      label = new JLabel("balance: " + account.getBalance());

      // Use helper methods 
      createButton();
      createPanel();

      setSize(FRAME_WIDTH, FRAME_HEIGHT);
   }

   private void createButton()
   {
      button = new JButton("Add Interest");
      ActionListener listener = new AddInterestListener();
      button.addActionListener(listener);
   }

   private void createPanel()
   {
      panel = new JPanel();
      panel.add(button);
      panel.add(label);      
      add(panel);
   }

   class AddInterestListener implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         double interest = account.getBalance() * INTEREST_RATE / 100;
         account.deposit(interest);
         label.setText("balance: " + account.getBalance());
      }            
   }   
}