public class BankView extends EFrame  
{
    private BankAccount modelAccount = new BankAccount();          // 1
    private ETextArea itsOutput = new ETextArea (10, 42);          // 2


  /** The View:  Lay out the GUI components. */

    public BankView()
    {   add (new LastFiveButton().text                           // 3
                ("show last five transactions"));               // 4
        add (new ELabel().text ("Enter deposit(+) or check(-)"));// 5
        add (new UpdateField().width (5).text ("0"));            // 6
        add (itsOutput);                                         // 7
        setVisible (true);                                       // 8
    }   //======================
    

  /** Controllers: React to click of button or ENTER key. */

    private class LastFiveButton extends EButton
    {   public void onClick()
        {   itsOutput.say (modelAccount.lastFiveTransactions());   // 9
        }
    }   //======================

    private class UpdateField extends EField
    {   public void onEnter()
        {   String input = this.getText();                         //10
            if (input == null || input.length() == 0)              //11
                return;                                          //12
            modelAccount.makeChange (input);                       //13
            itsOutput.say (modelAccount.currentBalance() +         //14
                    " = balance.");                            //15
        }
    }   //======================
}//#############################################################################







class BankViewApp
{
    public static void main (String[ ] args) 
    {   new BankView();
    }   //======================
}//#############################################################################








class BankAccount
{
    private int itsBalance = 0;
    private String itsFive = ".. .. .. .. ..";


    /** If the given String is not a properly-formed integer, do nothing;
        otherwise add it to the balance (which decreases the balance if it
        is a negative number, representing a check) and update 
        the last 5 transactions. */

    public void makeChange (String given)
    {   try
        {   int input = Integer.parseInt (given.trim());
            itsBalance += input;
            itsFive = itsFive.substring (itsFive.indexOf (" ") + 1) +
                        " " + input;
        } catch (Exception e)
        {   }   // do nothing if given is not a properly-formed integer
    }



    /** Tell the balance currently in the bank account. */

    public int currentBalance()
    {   return itsBalance;
    }


    /** Display the last 5 transactions, or all of them if less than 5. */

    public String lastFiveTransactions()
    {   return itsFive;
    }


    /* EXERCISE:  Change this so that there are 2 blanks between entries
              instead of just 1.
       EXERCISE:  Change this so that, for instance, a display of 48 -20 
              becomes dep48 chk20.
    */
}//#############################################################################