}        protected void makeItPretty(JComponent input) {            checkField(input, true);        }        protected boolean checkField(JComponent input, boolean changeIt) {            if (input == amountField) {                return checkAmountField(changeIt);            } else if (input == rateField) {                return checkRateField(changeIt);            } else if (input == numPeriodsField) {                return checkNumPeriodsField(changeIt);            } else {                return true; //shouldn't happen            }        }        //Checks that the amount field is valid.  If it is valid,        //it returns true, otherwise it sets the message field and        //returns false.  If the change argument is true,  set        //the textfield to the parsed number so that it looks        //good -- no letters, for example.        public boolean checkAmountField(boolean change) {            boolean wasValid = true;            double amount = DEFAULT_AMOUNT;            //Parse the value.            try {                amount = moneyFormat.parse(amountField.getText()).                                     doubleValue();            } catch (ParseException pe) {                message = "Invalid money format in Loan Amount field";                return false;            }            //Value was invalid.            if ((amount < MIN_AMOUNT) || (amount > MAX_AMOUNT)) {                wasValid = false;                if (amount < MIN_AMOUNT) {                    message = "Loan Amount was < "                              + integerFormat.format(MIN_AMOUNT);                } else { //amount is greater than MAX_AMOUNT                    message = "Loan Amount was > "                              + integerFormat.format(MAX_AMOUNT);                }            }            //Whether value was valid or not, format it nicely.            if (change) {                amountField.setText(moneyFormat.format(amount));                amountField.selectAll();            }            return wasValid;        }        //Checks that the rate field is valid.  If it is valid,        //it returns true, otherwise it sets the message field and        //returns false. If the change argument is true, set the        //textfield to the parsed number so that it looks good -- no         //letters, for example.        public boolean checkRateField(boolean change) {            boolean wasValid = true;            double rate = DEFAULT_RATE;            //Parse the value.            try {                rate = percentFormat.parse(rateField.getText()).                                     doubleValue();            } catch (ParseException pe) {                message = "Invalid percent format in APR field";                return false;            }            //Value was invalid.            if (rate < MIN_RATE) {                wasValid = false;                message = "Bad value: APR was < " + MIN_RATE;            }            //Whether value was valid or not, format it nicely.            if (change) {                rateField.setText(percentFormat.format(rate));                rateField.selectAll();            }            return wasValid;        }            //Checks that the numPeriods field is valid.  If it is valid,        //it returns true, otherwise it sets the message field and        //returns false. If the change argument is true, set the         //textfield to the parsed number so that it looks good -- no        //letters, for example.        public boolean checkNumPeriodsField(boolean change) {            boolean wasValid = true;            int numPeriods = DEFAULT_PERIOD;            //Parse the value.            try {                numPeriods = decimalFormat.parse(numPeriodsField.getText()).                                           intValue();            } catch (ParseException pe) {                message = "Invalid decimal format in Years field";                return false;            }                      //Value was invalid.            if (numPeriods < MIN_PERIOD) {                wasValid = false;                message = "Bad value: Number of years was < "                          + integerFormat.format(MIN_PERIOD);            } else if (numPeriods > MAX_PERIOD) {                wasValid = false;                message = "Bad value: Number of years was > "                          + integerFormat.format(MAX_PERIOD);            }            //Whether value was valid or not, format it nicely.            if (change) {                numPeriodsField.setText(decimalFormat.format(numPeriods));                numPeriodsField.selectAll();            }            return wasValid;        }        public void actionPerformed(ActionEvent e) {            JTextField source = (JTextField)e.getSource();            shouldYieldFocus(source); //ignore return value            source.selectAll();        }    }    /**     * Create the GUI and show it.  For thread safety,     * this method should be invoked from the     * event-dispatching thread.     */    private static void createAndShowGUI() {        //Create and set up the window.        JFrame frame = new JFrame("InputVerificationDialogDemo");        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        JComponent newContentPane = new InputVerificationDialogDemo();        newContentPane.setOpaque(true); //content panes must be opaque        frame.setContentPane(newContentPane);        //Display the window.        frame.pack();        frame.setVisible(true);    }    public static void main(String[] args) {	/* Use an appropriate Look and Feel */        try {            //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");            //UIManager.setLookAndFeel("com.sun.java.swing.plaf.gtk.GTKLookAndFeel");            UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");        } catch (UnsupportedLookAndFeelException ex) {            ex.printStackTrace();        } catch (IllegalAccessException ex) {            ex.printStackTrace();        } catch (InstantiationException ex) {            ex.printStackTrace();        } catch (ClassNotFoundException ex) {            ex.printStackTrace();        }        /* Turn off metal's use of bold fonts */        UIManager.put("swing.boldMetal", Boolean.FALSE);	            //Schedule a job for the event-dispatching thread:        //creating and showing this application's GUI.        javax.swing.SwingUtilities.invokeLater(new Runnable() {            public void run() {                createAndShowGUI();            }        });    }    //Compute the monthly payment based on the loan amount,    //APR, and length of loan.    double computePayment(double loanAmt, double rate, int numPeriods) {        double I, partial1, denominator, answer;        numPeriods *= 12;        //get number of months        if (rate > 0.01) {              I = rate / 100.0 / 12.0;         //get monthly rate from annual            partial1 = Math.pow((1 + I), (0.0 - numPeriods));            denominator = (1 - partial1) / I;        } else { //rate ~= 0            denominator = numPeriods;        }        answer = (-1 * loanAmt) / denominator;        return answer;    }    //Create and set up number formats. These objects also    //parse numbers input by user.    private void setUpFormats() {        moneyFormat = (NumberFormat)NumberFormat.getNumberInstance();        percentFormat = NumberFormat.getNumberInstance();        percentFormat.setMinimumFractionDigits(3);        decimalFormat = (DecimalFormat)NumberFormat.getNumberInstance();        decimalFormat.setParseIntegerOnly(true);        paymentFormat = (DecimalFormat)NumberFormat.getNumberInstance();        paymentFormat.setMaximumFractionDigits(2);        paymentFormat.setNegativePrefix("(");        paymentFormat.setNegativeSuffix(")");        integerFormat = NumberFormat.getIntegerInstance();    }}