import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; import javax.swing.text.*; import java.beans.PropertyChangeListener; import java.beans.PropertyChangeEvent; import java.text.*; /** * FormattedTextFieldDemo.java is a 1.4 example that * requires no other files. * * It implements a mortgage calculator that uses four * JFormattedTextFields. */ public class FormattedTextFieldDemo extends JPanel implements PropertyChangeListener { //Values for the fields private double amount = 100000; private double rate = 7.5; //7.5% private int numPeriods = 30; //Labels to identify the fields private JLabel amountLabel; private JLabel rateLabel; private JLabel numPeriodsLabel; private JLabel paymentLabel; //Strings for the labels private static String amountString = "Loan Amount: "; private static String rateString = "APR (%): "; private static String numPeriodsString = "Years: "; private static String paymentString = "Monthly Payment: "; //Fields for data entry private JFormattedTextField amountField; private JFormattedTextField rateField; private JFormattedTextField numPeriodsField; private JFormattedTextField paymentField; //Formats to format and parse numbers private NumberFormat amountFormat; private NumberFormat percentFormat; private NumberFormat paymentFormat; public FormattedTextFieldDemo() { super(new BorderLayout()); setUpFormats(); double payment = computePayment(amount, rate, numPeriods); //Create the labels. amountLabel = new JLabel(amountString); rateLabel = new JLabel(rateString); numPeriodsLabel = new JLabel(numPeriodsString); paymentLabel = new JLabel(paymentString); //Create the text fields and set them up. amountField = new JFormattedTextField(amountFormat); amountField.setValue(new Double(amount)); amountField.setColumns(10); amountField.addPropertyChangeListener("value", this); rateField = new JFormattedTextField(percentFormat); rateField.setValue(new Double(rate)); rateField.setColumns(10); rateField.addPropertyChangeListener("value", this); numPeriodsField = new JFormattedTextField(); numPeriodsField.setValue(new Integer(numPeriods)); numPeriodsField.setColumns(10); numPeriodsField.addPropertyChangeListener("value", this); paymentField = new JFormattedTextField(paymentFormat); paymentField.setValue(new Double(payment)); paymentField.setColumns(10); paymentField.setEditable(false); paymentField.setForeground(Color.red); //Tell accessibility tools about label/textfield pairs. amountLabel.setLabelFor(amountField); rateLabel.setLabelFor(rateField); numPeriodsLabel.setLabelFor(numPeriodsField); paymentLabel.setLabelFor(paymentField); //Lay out the labels in a panel. JPanel labelPane = new JPanel(new GridLayout(0,1)); labelPane.add(amountLabel); labelPane.add(rateLabel); labelPane.add(numPeriodsLabel); labelPane.add(paymentLabel); //Layout the text fields in a panel. JPanel fieldPane = new JPanel(new GridLayout(0,1)); fieldPane.add(amountField); fieldPane.add(rateField); fieldPane.add(numPeriodsField); fieldPane.add(paymentField); //Put the panels in this panel, labels on left, //text fields on right. setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20)); add(labelPane, BorderLayout.CENTER); add(fieldPane, BorderLayout.LINE_END); } /** Called when a field's "value" property changes. */ public void propertyChange(PropertyChangeEvent e) { Object source = e.getSource(); if (source == amountField) { amount = ((Number)amountField.getValue()).doubleValue(); } else if (source == rateField) { rate = ((Number)rateField.getValue()).doubleValue(); } else if (source == numPeriodsField) { numPeriods = ((Number)numPeriodsField.getValue()).intValue(); } double payment = computePayment(amount, rate, numPeriods); paymentField.setValue(new Double(payment)); } /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event-dispatching thread. */ private static void createAndShowGUI() { //Make sure we have nice window decorations. JFrame.setDefaultLookAndFeelDecorated(true); //Create and set up the window. JFrame frame = new JFrame("FormattedTextFieldDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. JComponent newContentPane = new FormattedTextFieldDemo(); 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) { //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() { amountFormat = NumberFormat.getNumberInstance(); percentFormat = NumberFormat.getNumberInstance(); percentFormat.setMinimumFractionDigits(3); paymentFormat = NumberFormat.getCurrencyInstance(); } }