I'm new to Java and following an online tutorial to learn swing.
I have just gotten to a part where we are adding in JCheckBox and I can't figure out why they are not showing up when I run the program. I'm running it on Eclipse on a Mac if that makes a difference.
I've tried re-writing everything but that didn't work. I know that they are added but they are just not showing up. The JRadioButtons are showing up just fine.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Userimputcomplex
{
public static void main(String[] args)
{
RadioDemo r = new RadioDemo();
}
}
class RadioDemo extends JFrame
{
JTextField t1; //Input Text
JButton b; //Button
JRadioButton r1,r2; //Check buttons
JLabel l; //Text
JCheckBox c1,c2; //Multiple check buttons
public RadioDemo()
{
t1 = new JTextField(15);
b = new JButton("Ok");
r1 = new JRadioButton("Male");
r2 = new JRadioButton("Female");
l = new JLabel("Greetings");
c1 = new JCheckBox("Dancing");
c2 = new JCheckBox("Singing");
ButtonGroup bg = new ButtonGroup();
bg.add(r1);
bg.add(r2);
add(t1);
add(r1);
add(r2);
add(c1);
add(c2);
add(b);
add(l);
b.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String name = t1.getText();
if(r1.isSelected())
{
name = "Mr." + name;
}
else
{
name = "Ms." + name;
}
if(c1.isSelected())
{
name = name + " Dancer";
}
if(c2.isSelected())
{
name = name + " Singer";
}
l.setText(name);
}
});
setLayout(new FlowLayout());
setVisible(true);
setSize(400, 400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
I've been trying to get te grips of Java (just because:)). At the moment I'm stuck on a 'calculator'. My intention is to select a overall subject through a ComboBox after which a second ComboBox shows which units can be calculated for said subject.
My problem is that the second ComboBox does not update and I'm having a hard time finding my oversight. Is anyone able to show my where I'm going wrong?
note: The terms for unitstring are placeholders for the time being:).
public class UserInterface implements Runnable{
String unitstring = "Select a subject";
#Override
public void run() {
JFrame frame = new JFrame("Radiation Calculator 2.0");
frame.setPreferredSize(new Dimension(350, 250));
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
createComponents(frame.getContentPane());
frame.pack();
frame.setVisible(true);
}
public void createComponents(Container container) {
GridLayout layout = new GridLayout(4, 2);
container.setLayout(layout);
JLabel subject = new JLabel("Select a subject");
String[] subjectStrings = {"Wavelenght", "Radioactive Decay", "Radiation Dose"};
JComboBox subjectsel = new JComboBox(subjectStrings);
subjectsel.addActionListener(this::actionPerformed);
JLabel unit = new JLabel("Select a unit");
String[] unitStrings = {unitstring};
JComboBox unitsel = new JComboBox(unitStrings);
JLabel input = new JLabel("Select a input");
JTextField userinput = new JTextField("");
JButton calculate = new JButton("Calculate");
JTextArea result = new JTextArea("");
container.add(subject);
container.add(subjectsel);
container.add(unit);
container.add(unitsel);
container.add(input);
container.add(userinput);
container.add(calculate);
container.add(result);
}
public void actionPerformed(ActionEvent e) {
JComboBox cb = (JComboBox) e.getSource();
int print = cb.getSelectedIndex();
System.out.println(print);
unitArray(print);
}
public void unitArray(int x) {
if (x == 0) {
unitstring = "Lambda";
}
if (x == 1) {
unitstring = "Bequerel";
}
if (x == 2) {
unitstring = "Gray";
}
System.out.println(unitstring);
}
}
I'm trying to create a simple program to manage Employees. When trying to add a new employee I can't seem to get the employee to be displayed on the Jlist.
The main frame...
public class EmployeeFrame extends JFrame implements ActionListener {
// The buttons to display
private JButton addButton;
private JButton editButton;
private JButton deleteButton;
private JButton saveButton;
// The underlying list of employees, and the GUI object to display them
private DefaultListModel<Employee> listModel;
private JList<Employee> employeeList;
public static final String SAVE_FILE = "employees.txt";
/**
* Creates and displays a new EmployeeFrame. The program exits when the
* window is closed.
*/
public EmployeeFrame() {
// Basic window features
super("Employee Manager");
setLocationByPlatform(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
// Try to make it look like a native application -- using try/multi-catch
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException
| UnsupportedLookAndFeelException e) {
e.printStackTrace();
}
// Initialise an empty list model, a JList to display it, and a scroll
// pane to contain the list
listModel = new DefaultListModel<>();
employeeList = new JList<>(listModel);
JScrollPane employeeScroll = new JScrollPane(employeeList);
employeeScroll.setBorder(new TitledBorder("Employee List"));
// Initialise all buttons and add the current class as an action
// listener to all
addButton = new JButton("Add Employee");
addButton.addActionListener(this);
editButton = new JButton("Edit Employee");
editButton.addActionListener(this);
deleteButton = new JButton("Delete Employee");
deleteButton.addActionListener(this);
saveButton = new JButton("Save Employee List");
saveButton.addActionListener(this);
// Lay out the buttons in a line
Box topBox = Box.createHorizontalBox();
topBox.add(addButton);
topBox.add(Box.createHorizontalStrut(10));
topBox.add(editButton);
topBox.add(Box.createHorizontalStrut(10));
topBox.add(deleteButton);
topBox.add(Box.createHorizontalStrut(10));
topBox.add(saveButton);
// Lay out the window
getContentPane().setLayout(new BorderLayout());
getContentPane().add(topBox, BorderLayout.NORTH);
getContentPane().add(employeeScroll, BorderLayout.CENTER);
pack();
}
public DefaultListModel<Employee> getListModel() {
return this.listModel;
}
#Override
public void actionPerformed(ActionEvent event) {
// Determine which button was pushed
Object source = event.getSource();
// Here's what to do with the delete button
if (source == deleteButton) {
Employee selection = employeeList.getSelectedValue();
if (selection != null) {
listModel.removeElement(selection);
}
}
if (source == addButton) {
AddEmployeeDialog frame = new AddEmployeeDialog(new EmployeeFrame());
frame.setVisible(true);
}
}
public static void main(String[] args) {
new EmployeeFrame().setVisible(true);
}
}
The dialogue that adds the employee...
public class AddEmployeeDialog extends JDialog implements ActionListener {
// Common fields
private JComboBox<String> workerType;
private JTextField givenNameField;
private JTextField familyNameField;
private JDatePicker startDatePicker;
// Fields that depend on the employee type
private JTextField rateField;
private JTextField hoursField;
private JTextField salaryField;
// Buttons
private JButton okButton;
private JButton cancelButton;
// The employee frame -- used to position the dialog and to access the
// employee list
private EmployeeFrame employeeFrame;
public AddEmployeeDialog(final EmployeeFrame frame) {
// Basic initialisation
super(frame, "Add Employee", true);
setLocationRelativeTo(employeeFrame);
this.employeeFrame = frame;
// Common fields
workerType = new JComboBox<String>(Employee.getEmployeeTypes());
givenNameField = new JTextField(20);
familyNameField = new JTextField(20);
startDatePicker = new JDateComponentFactory().createJDatePicker();
// Fields only for hourly workers
rateField = new JTextField(10);
hoursField = new JTextField(5);
// Field only for salaried worker
salaryField = new JTextField(10);
// Top line
Box workerBox = Box.createHorizontalBox();
workerBox.add(new JLabel("Worker type"));
workerBox.add(workerType);
workerBox.add(new JLabel("Start date"));
workerBox.add((JPanel) startDatePicker);
// Next lines (names)
Box givenNameBox = Box.createHorizontalBox();
givenNameBox.add(new JLabel("Given name "));
givenNameBox.add(givenNameField);
Box familyNameBox = Box.createHorizontalBox();
familyNameBox.add(new JLabel("Family name"));
familyNameBox.add(familyNameField);
// Hourly-worker fields
Box hourlyBox = Box.createHorizontalBox();
hourlyBox.setBorder(new TitledBorder("Hourly worker information"));
hourlyBox.add(new JLabel("Rate"));
hourlyBox.add(rateField);
hourlyBox.add(Box.createHorizontalStrut(10));
hourlyBox.add(new JLabel("Hours"));
hourlyBox.add(hoursField);
// Salaried-worker fields
Box salariedBox = Box.createHorizontalBox();
salariedBox.setBorder(new TitledBorder("Salaried worker information"));
salariedBox.add(new JLabel("Salary"));
salariedBox.add(salaryField);
// Ensure that only the appropriate fields are enabled, depending on the
// worker type chosen
workerType.addItemListener(new ItemListener() {
#Override
public void itemStateChanged(ItemEvent arg0) {
String type = (String) workerType.getSelectedItem();
salaryField.setEnabled("Salaried".equals(type));
rateField.setEnabled("Hourly".equals(type));
hoursField.setEnabled("Hourly".equals(type));
}
});
workerType.setSelectedItem(null);
// Create buttons and add the current class as an ActionListener
okButton = new JButton("OK");
okButton.addActionListener(this);
cancelButton = new JButton("Cancel");
cancelButton.addActionListener(this);
// Bottom row of GUI: buttons
Box bottomBox = Box.createHorizontalBox();
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(okButton);
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(cancelButton);
bottomBox.add(Box.createHorizontalGlue());
// Lay out the GUI
getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
getContentPane().add(workerBox);
getContentPane().add(givenNameBox);
getContentPane().add(familyNameBox);
getContentPane().add(hourlyBox);
getContentPane().add(salariedBox);
getContentPane().add(Box.createVerticalStrut(10));
getContentPane().add(bottomBox);
pack();
}
#Override
public void actionPerformed(ActionEvent event) {
// Convert the value from the date picker into a LocalDate
GregorianCalendar startDateValue = (GregorianCalendar) startDatePicker.getModel().getValue();
LocalDate startDate = startDateValue.toZonedDateTime().toLocalDate();
// Work out which button was pressed
Object source = event.getSource();
if (source == cancelButton) {
// Just close the window
dispose();
}
if (source == okButton) {
// Determine if the employee is hourly or salaried
if (workerType.getSelectedItem().toString() == "Salaried") {
// Create new salaried employee
if (salaryField.getText().matches("[0-9]+")) {
Employee employee = new SalariedEmployee(givenNameField.getText(),
familyNameField.getText(),
startDate,
Double.parseDouble(salaryField.getText()));
employeeFrame.getListModel().addElement(employee);
}
}
else {
// Create new hourly employee
if (rateField.getText().matches("[0-9]+") && hoursField.getText().matches("[0-9]+")) {
Employee employee = new HourlyEmployee(givenNameField.getText(),
familyNameField.getText(),
startDate,
Double.parseDouble(rateField.getText()),
Integer.parseInt(hoursField.getText()));
employeeFrame.getListModel().addElement(employee);
}
}
dispose();
}
}
}
This is what I'm using to add the employee
employeeFrame.getListModel().addElement(employee);
I think this is the right method but it doesn't seem to work. Any help will really be appreciated.
Two problems,
The first:
bad: if (workerType.getSelectedItem().toString() == "Salaried") {. Use equals(...) or equalsIgnoreCase(...). Understand that == checks for reference equality which is most definitely not what you're interested in. You want functional equality which is what the methods test for.
So: if ("Salaried".equalsIgnoreCase(workerType.getSelectedItem().toString())) {
The second:
AddEmployeeDialog frame = new AddEmployeeDialog(new EmployeeFrame());
You're passing in a new EmployeeFrame object meaning you're updating the list model for the wrong EmployeeFrame. Instead pass in the visualized EmployeeFrame.
Change it to:
AddEmployeeDialog frame = new AddEmployeeDialog(EmployeeFrame.this);
My program that I created to shrink your code but still allow it to be runnable and to demonstrate your problem:
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.TitledBorder;
#SuppressWarnings("serial")
public class EmployeeFrame extends JFrame implements ActionListener {
private JButton addButton;
private DefaultListModel<Employee> listModel;
private JList<Employee> employeeList;
public EmployeeFrame() {
super("Employee Manager");
setLocationByPlatform(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
listModel = new DefaultListModel<>();
employeeList = new JList<>(listModel);
JScrollPane employeeScroll = new JScrollPane(employeeList);
employeeScroll.setBorder(new TitledBorder("Employee List"));
addButton = new JButton("Add Employee");
addButton.addActionListener(this);
Box topBox = Box.createHorizontalBox();
topBox.add(addButton);
getContentPane().setLayout(new BorderLayout());
getContentPane().add(topBox, BorderLayout.NORTH);
getContentPane().add(employeeScroll, BorderLayout.CENTER);
pack();
}
public DefaultListModel<Employee> getListModel() {
return this.listModel;
}
#Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
if (source == addButton) {
// !! AddEmployeeDialog frame = new AddEmployeeDialog(new EmployeeFrame());
AddEmployeeDialog frame = new AddEmployeeDialog(EmployeeFrame.this);
frame.setVisible(true);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new EmployeeFrame().setVisible(true);
}
});
}
}
#SuppressWarnings("serial")
class AddEmployeeDialog extends JDialog implements ActionListener {
private JComboBox<String> workerType;
private JTextField givenNameField;
private JTextField familyNameField;
private JButton okButton;
private JButton cancelButton;
private EmployeeFrame employeeFrame;
public AddEmployeeDialog(final EmployeeFrame frame) {
super(frame, "Add Employee", true);
setLocationRelativeTo(employeeFrame);
this.employeeFrame = frame;
workerType = new JComboBox<String>(Employee.getEmployeeTypes());
givenNameField = new JTextField(20);
familyNameField = new JTextField(20);
Box workerBox = Box.createHorizontalBox();
workerBox.add(new JLabel("Worker type"));
workerBox.add(workerType);
workerBox.add(new JLabel("Start date"));
Box givenNameBox = Box.createHorizontalBox();
givenNameBox.add(new JLabel("Given name "));
givenNameBox.add(givenNameField);
Box familyNameBox = Box.createHorizontalBox();
familyNameBox.add(new JLabel("Family name"));
familyNameBox.add(familyNameField);
workerType.setSelectedItem(null);
// Create buttons and add the current class as an ActionListener
okButton = new JButton("OK");
okButton.addActionListener(this);
cancelButton = new JButton("Cancel");
cancelButton.addActionListener(this);
Box bottomBox = Box.createHorizontalBox();
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(okButton);
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(cancelButton);
bottomBox.add(Box.createHorizontalGlue());
// Lay out the GUI
getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
getContentPane().add(workerBox);
getContentPane().add(givenNameBox);
getContentPane().add(familyNameBox);
getContentPane().add(Box.createVerticalStrut(10));
getContentPane().add(bottomBox);
pack();
}
#Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
if (source == okButton) {
System.out.println("here");
System.out.println(workerType.getSelectedItem());
if ("Salaried".equalsIgnoreCase(workerType.getSelectedItem().toString())) {
Employee employee = new Employee("Salaried", givenNameField.getText(), familyNameField.getText());
employeeFrame.getListModel().addElement(employee);
} else {
Employee employee = new Employee("Hourly", givenNameField.getText(), familyNameField.getText());
employeeFrame.getListModel().addElement(employee);
}
}
dispose();
}
}
class Employee {
private static final String[] EMPLOYEE_TYPES = { "Salaried", "Hourly" };
private String givenName;
private String familyName;
private String type;
public Employee(String type, String givenName, String familyName) {
this.type = type;
this.givenName = givenName;
this.familyName = familyName;
}
public static String[] getEmployeeTypes() {
return EMPLOYEE_TYPES;
}
public String getGivenName() {
return givenName;
}
public String getFamilyName() {
return familyName;
}
public String getType() {
return type;
}
#Override
public String toString() {
return String.format("Employee: %s, %s %s", type, givenName, familyName);
}
}
There is 3 panels which I created as seen in the image. The first panel is the "From" panel, second is "To" panel, and third is the buttons panel. So the question is, how can I put a new line for the "Enter Temperature: [ ]" so that it will be under neath the radio buttons? I am very new to Java swing/awt please bear with me.
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import java.awt.*;
public class TemperatureConversion extends JFrame{
// component
JTextField txtFromTemp, txtToTemp;
JLabel lblFromTemp, lblToTemp;
JRadioButton radFromCelsius, radFromFahrenheit, radFromKelvin;
JRadioButton radToCelsius, radToFahrenheit, radToKelvin;
JPanel pnlFromRadioButton, pnlToRadioButton, pnlFromTemp, pnlButton;
ButtonGroup bgFrom, bgTo;
JButton btnConvert, btnExit;
// constructor
public TemperatureConversion(){
super("Temperature");
// assign objects
radFromCelsius = new JRadioButton("Celsius", true);
radFromFahrenheit = new JRadioButton("Fahrenheit");
radFromKelvin = new JRadioButton("Kelvin");
lblFromTemp = new JLabel("Enter Temperature: ");
pnlFromTemp = new JPanel();
btnConvert = new JButton("Convert");
btnExit = new JButton("Exit");
pnlButton = new JPanel();
txtFromTemp = new JTextField(3);
lblToTemp = new JLabel("Comparable Temperature: ");
txtToTemp = new JTextField(3);
// register the button to a listener
btnExit.addActionListener(new MyButtonListener());
btnConvert.addActionListener(new MyButtonListener());
// make the multiple choice exclusive but not a container
bgFrom = new ButtonGroup();
bgFrom.add(radFromCelsius);
bgFrom.add(radFromFahrenheit);
bgFrom.add(radFromKelvin);
// radio buttons
radToCelsius = new JRadioButton("Celsius");
radToFahrenheit = new JRadioButton("Fahrenheit", true);
radToKelvin = new JRadioButton("Kelvin");
// make the multiple choice exclusive
bgTo = new ButtonGroup();
bgTo.add(radToCelsius);
bgTo.add(radToFahrenheit);
bgTo.add(radToKelvin);
pnlFromRadioButton = new JPanel();
pnlToRadioButton = new JPanel();
// decorate the panel
pnlFromRadioButton.setBorder(BorderFactory.createTitledBorder("From"));
pnlToRadioButton.setBorder(BorderFactory.createTitledBorder("To"));
// add radiobutton to panel
pnlFromRadioButton.add(radFromCelsius);
pnlFromRadioButton.add(radFromFahrenheit);
pnlFromRadioButton.add(radFromKelvin);
pnlToRadioButton.add(radToCelsius);
pnlToRadioButton.add(radToFahrenheit);
pnlToRadioButton.add(radToKelvin);
// add button to panel
pnlButton.add(btnConvert);
pnlButton.add(btnExit);
// add label and txt field to panel
pnlFromRadioButton.add(lblFromTemp);
pnlFromRadioButton.add(txtFromTemp);
pnlToRadioButton.add(lblToTemp);
txtToTemp.setEditable(false);
pnlToRadioButton.add(txtToTemp);
// add panels to the frame
add(pnlFromRadioButton, BorderLayout.NORTH);
add(pnlToRadioButton, BorderLayout.CENTER);
add(pnlButton, BorderLayout.SOUTH);
setVisible(true);
setSize(400, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
}
// private inner class to handle button event
private class MyButtonListener implements ActionListener {
// must override actionPerformed method
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == btnConvert) {
if (radFromCelsius.isSelected())
System.out.print("exit");
} else if (e.getSource() == btnExit) {
System.exit(0);
}
}
}
public static void main(String[] args) {
new TemperatureConversion();
}
}
Nest more JPanels and use layout managers
For instance, in the JPanel where you want two lines, give it a BoxLayout oriented along the BoxLayout.PAGE_AXIS, and then add two more JPanels to this BoxLayout-using, a top JPanel with the radio buttons and bottom JPanel with the JLabel and JTextField (or whatever else you want in it).
Side note: this would be a great place to use an enum one called TempScale that had three values: CELSIUS, FAHRENHEIT, KELVIN. You could even give the enum the formulas for conversion to and from Kelvin.
For example:
import java.awt.Component;
import java.awt.event.*;
import java.util.HashMap;
import java.util.Map;
import javax.swing.*;
#SuppressWarnings("serial")
public class TempConversion2 extends JPanel {
private ToFromPanel fromPanel = new ToFromPanel("From", true);
private ToFromPanel toPanel = new ToFromPanel("To", false);
private ButtonPanel buttonPanel = new ButtonPanel(fromPanel, toPanel);
public TempConversion2() {
setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
add(fromPanel);
add(toPanel);
add(buttonPanel);
}
private static void createAndShowGui() {
TempConversion2 mainPanel = new TempConversion2();
JFrame frame = new JFrame("Temp Convert");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
#SuppressWarnings("serial")
class ButtonPanel extends JPanel {
public ButtonPanel(ToFromPanel fromPanel, ToFromPanel toPanel) {
add(new JButton(new ConvertAction("Convert", fromPanel, toPanel)));
add(new JButton(new ExitAction("Exit", KeyEvent.VK_X)));
}
}
#SuppressWarnings("serial")
class ConvertAction extends AbstractAction {
private ToFromPanel fromPanel;
private ToFromPanel toPanel;
public ConvertAction(String name, ToFromPanel fromPanel, ToFromPanel toPanel) {
super(name);
int mnemonic = (int) name.charAt(0);
putValue(MNEMONIC_KEY, mnemonic);
this.fromPanel = fromPanel;
this.toPanel = toPanel;
}
#Override
public void actionPerformed(ActionEvent e) {
String text = fromPanel.getText();
try {
double fromTemp = Double.parseDouble(text.trim());
TempScale fromScale = fromPanel.getTempScalesPanel().getSelectedTempScale();
double kelvinValue = fromScale.convertToKelvin(fromTemp);
TempScale toScale = toPanel.getTempScalesPanel().getSelectedTempScale();
double toValue = toScale.convertFromKelvin(kelvinValue);
String toValueString = String.format("%.2f", toValue);
toPanel.setText(toValueString);
} catch (NumberFormatException e1) {
Component parentComponent = fromPanel;
String message = "Text must be a valid number: " + text;
String title = "Invalid Text Entered";
int messageType = JOptionPane.ERROR_MESSAGE;
JOptionPane.showMessageDialog(parentComponent, message, title, messageType);
fromPanel.setText("");
}
}
}
#SuppressWarnings("serial")
class ExitAction extends AbstractAction {
public ExitAction(String name, int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
}
#SuppressWarnings("serial")
class ToFromPanel extends JPanel {
private String title;
private TempScalesPanel tempScalesPanel = new TempScalesPanel();
private JTextField tempTextField = new JTextField(3);
public ToFromPanel(String title, boolean textFieldEnabled) {
this.title = title;
tempTextField.setFocusable(textFieldEnabled);
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.LINE_AXIS));
bottomPanel.setBorder(BorderFactory.createEmptyBorder(2, 2, 2, 2));
bottomPanel.add(new JLabel("Temperature:"));
bottomPanel.add(Box.createHorizontalStrut(8));
bottomPanel.add(tempTextField);
setBorder(BorderFactory.createTitledBorder(title));
setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
add(tempScalesPanel);
add(bottomPanel);
}
public String getTitle() {
return title;
}
public TempScalesPanel getTempScalesPanel() {
return tempScalesPanel;
}
public String getText() {
return tempTextField.getText();
}
public void setText(String text) {
tempTextField.setText(text);
}
}
#SuppressWarnings("serial")
class TempScalesPanel extends JPanel {
private ButtonGroup buttonGroup = new ButtonGroup();
private Map<ButtonModel, TempScale> buttonTempMap = new HashMap<>();
public TempScalesPanel() {
for (TempScale tempScale : TempScale.values()) {
JRadioButton radioButton = new JRadioButton(tempScale.getName());
add(radioButton);
buttonGroup.add(radioButton);
buttonTempMap.put(radioButton.getModel(), tempScale);
// set first button as selected by default
if (buttonGroup.getSelection() == null) {
buttonGroup.setSelected(radioButton.getModel(), true);
}
}
}
public TempScale getSelectedTempScale() {
ButtonModel model = buttonGroup.getSelection();
return buttonTempMap.get(model);
}
}
This is the enum that I was talking about. Note that if you change the enum, and for instance add another temperature scale element, the program will automatically include it in the GUI and in the calculations. God I love Java and OOP.
public enum TempScale {
CELSIUS("Celsius", 1.0, -273.15),
FAHRENHEIT("Fahrenheit", 5.0 / 9.0, -459.67),
KELVIN("Kelvin", 1.0, 0.0);
private TempScale(String name, double ratioToKelvin, double absZero) {
this.name = name;
this.ratioToKelvin = ratioToKelvin;
this.absZero = absZero;
}
private String name;
private double ratioToKelvin;
private double absZero;
public String getName() {
return name;
}
public double getRatioToKelvin() {
return ratioToKelvin;
}
public double getAbsZero() {
return absZero;
}
public double convertToKelvin(double value) {
return (value - absZero) * ratioToKelvin;
}
public double convertFromKelvin(double kelvinValue) {
return (kelvinValue / ratioToKelvin) + absZero;
}
}
Always consider posting an MCVE.
For example you layout can be simplified and demonstrated with :
import java.awt.BorderLayout;
import java.awt.Label;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TemperatureConversion extends JFrame{
JPanel pnlFromRadioButton, pnlToRadioButton, pnlFromTemp, pnlButton;
// constructor
public TemperatureConversion(){
pnlFromRadioButton = new JPanel();
pnlFromRadioButton.add(new Label("From Panel"));
pnlToRadioButton = new JPanel();
pnlToRadioButton.add(new Label("To Panel"));
pnlButton = new JPanel();
pnlButton.add(new Label("Buttons Panel"));
// add panels to the frame
add(pnlFromRadioButton, BorderLayout.NORTH);
add(pnlToRadioButton, BorderLayout.CENTER);
add(pnlButton, BorderLayout.SOUTH);
setVisible(true);
setSize(400, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new TemperatureConversion();
}
}
Suppose you want to an "Enter Temperature: [ ]" label to show in a different "line" under From buttons, your constructor will change to :
public TemperatureConversion(){
//set a layout manger. You could use grid layout
//GridLayout gridLayout = new GridLayout(4, 1);
//Or BoxLayout
BoxLayout boxLayout = new BoxLayout(getContentPane(), BoxLayout.Y_AXIS); // top to bottom
setLayout(boxLayout);
pnlFromRadioButton = new JPanel();
pnlFromRadioButton.add(new Label("From Panel"));
//create a panel to hold the desired label
pnlFromTemp = new JPanel();
pnlFromTemp.add(new JLabel("Enter Temperature: [ ]"));//add label
pnlToRadioButton = new JPanel();
pnlToRadioButton.add(new Label("To Panel"));
pnlButton = new JPanel();
pnlButton.add(new Label("Buttons Panel"));
// add panels to the frame
//the panel will show in the order added
add(pnlFromRadioButton);
add(pnlFromTemp);
add(pnlToRadioButton);
add(pnlButton);
setVisible(true);
setSize(400, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
Sorry I am new to forums and am not familiar with posting etiquette for codes #c0der. But using GridLayout solved my problem and I want to show you what I did, it is a big mess but here it is. Here is my bizarre code but don't know how to reduce it any further. This is how it is suppose to look as I wanted and because now I understand what you mean by "Nest more JPanels and use layout managers" #Hovercraft Full of Eels:
my temperature program
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import java.awt.*;
public class TemperatureConversion extends JFrame {
// component
JTextField txtFromTemp, txtToTemp;
JLabel lblFromTemp, lblToTemp, lblToTempbox;
JRadioButton radFromCelsius, radFromFahrenheit, radFromKelvin;
JRadioButton radToCelsius, radToFahrenheit, radToKelvin;
JPanel pnlFromRadioButton, pnlToRadioButton, pnlFrom, pnlTo, pnlButton;
JPanel pnlEnterTemp, pnlComparableTemp;
ButtonGroup bgFrom, bgTo;
JButton btnConvert, btnExit;
// constructor
public TemperatureConversion() {
super("Temperature");
// assign objects
radFromCelsius = new JRadioButton("Celsius", true);
radFromFahrenheit = new JRadioButton("Fahrenheit");
radFromKelvin = new JRadioButton("Kelvin");
lblFromTemp = new JLabel("Enter Temperature: ");
pnlFrom = new JPanel();
btnConvert = new JButton("Convert");
btnExit = new JButton("Exit");
pnlButton = new JPanel();
txtFromTemp = new JTextField(3);
lblToTemp = new JLabel("Comparable Temperature: ");
txtToTemp = new JTextField(3);
pnlTo = new JPanel();
pnlEnterTemp = new JPanel();
pnlComparableTemp = new JPanel();
pnlFromRadioButton = new JPanel();
pnlToRadioButton = new JPanel();
// register the button to a listener
btnExit.addActionListener(new MyButtonListener());
btnConvert.addActionListener(new MyButtonListener());
// make the multiple choice exclusive but not a container
bgFrom = new ButtonGroup();
bgFrom.add(radFromCelsius);
bgFrom.add(radFromFahrenheit);
bgFrom.add(radFromKelvin);
// radio buttons
radToCelsius = new JRadioButton("Celsius");
radToFahrenheit = new JRadioButton("Fahrenheit", true);
radToKelvin = new JRadioButton("Kelvin");
// make the multiple choice exclusive
bgTo = new ButtonGroup();
bgTo.add(radToCelsius);
bgTo.add(radToFahrenheit);
bgTo.add(radToKelvin);
pnlFrom.setLayout(new GridLayout(2, 1));
pnlFrom.add(pnlFromRadioButton);
pnlFrom.add(pnlEnterTemp);
pnlTo.setLayout(new GridLayout(2, 1));
pnlTo.add(pnlToRadioButton);
pnlTo.add(pnlComparableTemp);
// decorate the panel
pnlFrom.setBorder(BorderFactory.createTitledBorder("From"));
pnlTo.setBorder(BorderFactory.createTitledBorder("To"));
// add radiobutton to panel
pnlFromRadioButton.add(radFromCelsius);
pnlFromRadioButton.add(radFromFahrenheit);
pnlFromRadioButton.add(radFromKelvin);
pnlToRadioButton.add(radToCelsius);
pnlToRadioButton.add(radToFahrenheit);
pnlToRadioButton.add(radToKelvin);
// add button to panel
pnlButton.add(btnConvert);
pnlButton.add(btnExit);
// add label and txt field to panel
pnlEnterTemp.add(lblFromTemp);
pnlEnterTemp.add(txtFromTemp);
pnlComparableTemp.add(lblToTemp);
txtToTemp.setEditable(false);
pnlComparableTemp.add(txtToTemp);
// add panels to the frame
add(pnlFrom, BorderLayout.NORTH);
add(pnlTo, BorderLayout.CENTER);
add(pnlButton, BorderLayout.SOUTH);
setVisible(true);
setSize(400, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
}
// private inner class to handle button event
private class MyButtonListener implements ActionListener {
// must override actionPerformed method
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == btnConvert) {
if (radFromCelsius.isSelected() && radToFahrenheit.isSelected()) {
int strInput = Integer.parseInt(txtFromTemp.getText());
int celsius = strInput * 9 / 5 + 32;
txtToTemp.setText(Integer.toString(celsius));
} else if (radFromCelsius.isSelected() && radToCelsius.isSelected() ||
radFromFahrenheit.isSelected() && radToFahrenheit.isSelected() ||
radFromKelvin.isSelected() && radToKelvin.isSelected()) {
txtToTemp.setText(txtFromTemp.getText());
} else if (radToCelsius.isSelected() && radFromFahrenheit.isSelected()) {
int strInput = Integer.parseInt(txtFromTemp.getText());
int fahrenheit = (strInput - 32) * 5 / 9;
txtToTemp.setText(Integer.toString(fahrenheit));
} else if (radFromKelvin.isSelected() && radToCelsius.isSelected()) {
double strInput = Integer.parseInt(txtFromTemp.getText());
double celsius = strInput - 273.15;
txtToTemp.setText(Double.toString(celsius));
} else if (radFromKelvin.isSelected() && radToFahrenheit.isSelected()) {
double strInput = Integer.parseInt(txtFromTemp.getText());
double fahrenheit = strInput - 459.67;
txtToTemp.setText(Double.toString(fahrenheit));
} else if (radFromCelsius.isSelected() && radToKelvin.isSelected()) {
double strInput = Integer.parseInt(txtFromTemp.getText());
double celsius = strInput + 273.15;
txtToTemp.setText(Double.toString(celsius));
} else if (radFromFahrenheit.isSelected() && radToKelvin.isSelected()) {
double strInput = Integer.parseInt(txtFromTemp.getText());
double fahrenheit = strInput + 255.37;
txtToTemp.setText(Double.toString(fahrenheit));
}
} else if (e.getSource() == btnExit) {
System.exit(0);
}
}
}
public static void main(String[] args) {
new TemperatureConversion();
}
}
By the way #Hovercraft Full Of Eels, your solution is way more efficient and advanced than my level of thinking. I am newbie to programming in general so bear with me on my messy code and organization lol. I have barely dipped my feet into OOP. I do have a sense of how you used enum for TempScale and I thank you for your suggestion. I will keep these in my notes as references.
I'm trying to create a simple program to manage Employees. When trying to add a new employee I can't seem to get the employee to be displayed on the Jlist.
The main frame...
public class EmployeeFrame extends JFrame implements ActionListener {
// The buttons to display
private JButton addButton;
private JButton editButton;
private JButton deleteButton;
private JButton saveButton;
// The underlying list of employees, and the GUI object to display them
private DefaultListModel<Employee> listModel;
private JList<Employee> employeeList;
public static final String SAVE_FILE = "employees.txt";
/**
* Creates and displays a new EmployeeFrame. The program exits when the
* window is closed.
*/
public EmployeeFrame() {
// Basic window features
super("Employee Manager");
setLocationByPlatform(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
// Try to make it look like a native application -- using try/multi-catch
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException
| UnsupportedLookAndFeelException e) {
e.printStackTrace();
}
// Initialise an empty list model, a JList to display it, and a scroll
// pane to contain the list
listModel = new DefaultListModel<>();
employeeList = new JList<>(listModel);
JScrollPane employeeScroll = new JScrollPane(employeeList);
employeeScroll.setBorder(new TitledBorder("Employee List"));
// Initialise all buttons and add the current class as an action
// listener to all
addButton = new JButton("Add Employee");
addButton.addActionListener(this);
editButton = new JButton("Edit Employee");
editButton.addActionListener(this);
deleteButton = new JButton("Delete Employee");
deleteButton.addActionListener(this);
saveButton = new JButton("Save Employee List");
saveButton.addActionListener(this);
// Lay out the buttons in a line
Box topBox = Box.createHorizontalBox();
topBox.add(addButton);
topBox.add(Box.createHorizontalStrut(10));
topBox.add(editButton);
topBox.add(Box.createHorizontalStrut(10));
topBox.add(deleteButton);
topBox.add(Box.createHorizontalStrut(10));
topBox.add(saveButton);
// Lay out the window
getContentPane().setLayout(new BorderLayout());
getContentPane().add(topBox, BorderLayout.NORTH);
getContentPane().add(employeeScroll, BorderLayout.CENTER);
pack();
}
public DefaultListModel<Employee> getListModel() {
return this.listModel;
}
#Override
public void actionPerformed(ActionEvent event) {
// Determine which button was pushed
Object source = event.getSource();
// Here's what to do with the delete button
if (source == deleteButton) {
Employee selection = employeeList.getSelectedValue();
if (selection != null) {
listModel.removeElement(selection);
}
}
if (source == addButton) {
AddEmployeeDialog frame = new AddEmployeeDialog(new EmployeeFrame());
frame.setVisible(true);
}
}
public static void main(String[] args) {
new EmployeeFrame().setVisible(true);
}
}
The dialogue that adds the employee...
public class AddEmployeeDialog extends JDialog implements ActionListener {
// Common fields
private JComboBox<String> workerType;
private JTextField givenNameField;
private JTextField familyNameField;
private JDatePicker startDatePicker;
// Fields that depend on the employee type
private JTextField rateField;
private JTextField hoursField;
private JTextField salaryField;
// Buttons
private JButton okButton;
private JButton cancelButton;
// The employee frame -- used to position the dialog and to access the
// employee list
private EmployeeFrame employeeFrame;
public AddEmployeeDialog(final EmployeeFrame frame) {
// Basic initialisation
super(frame, "Add Employee", true);
setLocationRelativeTo(employeeFrame);
this.employeeFrame = frame;
// Common fields
workerType = new JComboBox<String>(Employee.getEmployeeTypes());
givenNameField = new JTextField(20);
familyNameField = new JTextField(20);
startDatePicker = new JDateComponentFactory().createJDatePicker();
// Fields only for hourly workers
rateField = new JTextField(10);
hoursField = new JTextField(5);
// Field only for salaried worker
salaryField = new JTextField(10);
// Top line
Box workerBox = Box.createHorizontalBox();
workerBox.add(new JLabel("Worker type"));
workerBox.add(workerType);
workerBox.add(new JLabel("Start date"));
workerBox.add((JPanel) startDatePicker);
// Next lines (names)
Box givenNameBox = Box.createHorizontalBox();
givenNameBox.add(new JLabel("Given name "));
givenNameBox.add(givenNameField);
Box familyNameBox = Box.createHorizontalBox();
familyNameBox.add(new JLabel("Family name"));
familyNameBox.add(familyNameField);
// Hourly-worker fields
Box hourlyBox = Box.createHorizontalBox();
hourlyBox.setBorder(new TitledBorder("Hourly worker information"));
hourlyBox.add(new JLabel("Rate"));
hourlyBox.add(rateField);
hourlyBox.add(Box.createHorizontalStrut(10));
hourlyBox.add(new JLabel("Hours"));
hourlyBox.add(hoursField);
// Salaried-worker fields
Box salariedBox = Box.createHorizontalBox();
salariedBox.setBorder(new TitledBorder("Salaried worker information"));
salariedBox.add(new JLabel("Salary"));
salariedBox.add(salaryField);
// Ensure that only the appropriate fields are enabled, depending on the
// worker type chosen
workerType.addItemListener(new ItemListener() {
#Override
public void itemStateChanged(ItemEvent arg0) {
String type = (String) workerType.getSelectedItem();
salaryField.setEnabled("Salaried".equals(type));
rateField.setEnabled("Hourly".equals(type));
hoursField.setEnabled("Hourly".equals(type));
}
});
workerType.setSelectedItem(null);
// Create buttons and add the current class as an ActionListener
okButton = new JButton("OK");
okButton.addActionListener(this);
cancelButton = new JButton("Cancel");
cancelButton.addActionListener(this);
// Bottom row of GUI: buttons
Box bottomBox = Box.createHorizontalBox();
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(okButton);
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(cancelButton);
bottomBox.add(Box.createHorizontalGlue());
// Lay out the GUI
getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
getContentPane().add(workerBox);
getContentPane().add(givenNameBox);
getContentPane().add(familyNameBox);
getContentPane().add(hourlyBox);
getContentPane().add(salariedBox);
getContentPane().add(Box.createVerticalStrut(10));
getContentPane().add(bottomBox);
pack();
}
#Override
public void actionPerformed(ActionEvent event) {
// Convert the value from the date picker into a LocalDate
GregorianCalendar startDateValue = (GregorianCalendar) startDatePicker.getModel().getValue();
LocalDate startDate = startDateValue.toZonedDateTime().toLocalDate();
// Work out which button was pressed
Object source = event.getSource();
if (source == cancelButton) {
// Just close the window
dispose();
}
if (source == okButton) {
// Determine if the employee is hourly or salaried
if (workerType.getSelectedItem().toString() == "Salaried") {
// Create new salaried employee
if (salaryField.getText().matches("[0-9]+")) {
Employee employee = new SalariedEmployee(givenNameField.getText(),
familyNameField.getText(),
startDate,
Double.parseDouble(salaryField.getText()));
employeeFrame.getListModel().addElement(employee);
}
}
else {
// Create new hourly employee
if (rateField.getText().matches("[0-9]+") && hoursField.getText().matches("[0-9]+")) {
Employee employee = new HourlyEmployee(givenNameField.getText(),
familyNameField.getText(),
startDate,
Double.parseDouble(rateField.getText()),
Integer.parseInt(hoursField.getText()));
employeeFrame.getListModel().addElement(employee);
}
}
dispose();
}
}
}
This is what I'm using to add the employee
employeeFrame.getListModel().addElement(employee);
I think this is the right method but it doesn't seem to work. Any help will really be appreciated.
Two problems,
The first:
bad: if (workerType.getSelectedItem().toString() == "Salaried") {. Use equals(...) or equalsIgnoreCase(...). Understand that == checks for reference equality which is most definitely not what you're interested in. You want functional equality which is what the methods test for.
So: if ("Salaried".equalsIgnoreCase(workerType.getSelectedItem().toString())) {
The second:
AddEmployeeDialog frame = new AddEmployeeDialog(new EmployeeFrame());
You're passing in a new EmployeeFrame object meaning you're updating the list model for the wrong EmployeeFrame. Instead pass in the visualized EmployeeFrame.
Change it to:
AddEmployeeDialog frame = new AddEmployeeDialog(EmployeeFrame.this);
My program that I created to shrink your code but still allow it to be runnable and to demonstrate your problem:
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.TitledBorder;
#SuppressWarnings("serial")
public class EmployeeFrame extends JFrame implements ActionListener {
private JButton addButton;
private DefaultListModel<Employee> listModel;
private JList<Employee> employeeList;
public EmployeeFrame() {
super("Employee Manager");
setLocationByPlatform(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
listModel = new DefaultListModel<>();
employeeList = new JList<>(listModel);
JScrollPane employeeScroll = new JScrollPane(employeeList);
employeeScroll.setBorder(new TitledBorder("Employee List"));
addButton = new JButton("Add Employee");
addButton.addActionListener(this);
Box topBox = Box.createHorizontalBox();
topBox.add(addButton);
getContentPane().setLayout(new BorderLayout());
getContentPane().add(topBox, BorderLayout.NORTH);
getContentPane().add(employeeScroll, BorderLayout.CENTER);
pack();
}
public DefaultListModel<Employee> getListModel() {
return this.listModel;
}
#Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
if (source == addButton) {
// !! AddEmployeeDialog frame = new AddEmployeeDialog(new EmployeeFrame());
AddEmployeeDialog frame = new AddEmployeeDialog(EmployeeFrame.this);
frame.setVisible(true);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new EmployeeFrame().setVisible(true);
}
});
}
}
#SuppressWarnings("serial")
class AddEmployeeDialog extends JDialog implements ActionListener {
private JComboBox<String> workerType;
private JTextField givenNameField;
private JTextField familyNameField;
private JButton okButton;
private JButton cancelButton;
private EmployeeFrame employeeFrame;
public AddEmployeeDialog(final EmployeeFrame frame) {
super(frame, "Add Employee", true);
setLocationRelativeTo(employeeFrame);
this.employeeFrame = frame;
workerType = new JComboBox<String>(Employee.getEmployeeTypes());
givenNameField = new JTextField(20);
familyNameField = new JTextField(20);
Box workerBox = Box.createHorizontalBox();
workerBox.add(new JLabel("Worker type"));
workerBox.add(workerType);
workerBox.add(new JLabel("Start date"));
Box givenNameBox = Box.createHorizontalBox();
givenNameBox.add(new JLabel("Given name "));
givenNameBox.add(givenNameField);
Box familyNameBox = Box.createHorizontalBox();
familyNameBox.add(new JLabel("Family name"));
familyNameBox.add(familyNameField);
workerType.setSelectedItem(null);
// Create buttons and add the current class as an ActionListener
okButton = new JButton("OK");
okButton.addActionListener(this);
cancelButton = new JButton("Cancel");
cancelButton.addActionListener(this);
Box bottomBox = Box.createHorizontalBox();
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(okButton);
bottomBox.add(Box.createHorizontalGlue());
bottomBox.add(cancelButton);
bottomBox.add(Box.createHorizontalGlue());
// Lay out the GUI
getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));
getContentPane().add(workerBox);
getContentPane().add(givenNameBox);
getContentPane().add(familyNameBox);
getContentPane().add(Box.createVerticalStrut(10));
getContentPane().add(bottomBox);
pack();
}
#Override
public void actionPerformed(ActionEvent event) {
Object source = event.getSource();
if (source == okButton) {
System.out.println("here");
System.out.println(workerType.getSelectedItem());
if ("Salaried".equalsIgnoreCase(workerType.getSelectedItem().toString())) {
Employee employee = new Employee("Salaried", givenNameField.getText(), familyNameField.getText());
employeeFrame.getListModel().addElement(employee);
} else {
Employee employee = new Employee("Hourly", givenNameField.getText(), familyNameField.getText());
employeeFrame.getListModel().addElement(employee);
}
}
dispose();
}
}
class Employee {
private static final String[] EMPLOYEE_TYPES = { "Salaried", "Hourly" };
private String givenName;
private String familyName;
private String type;
public Employee(String type, String givenName, String familyName) {
this.type = type;
this.givenName = givenName;
this.familyName = familyName;
}
public static String[] getEmployeeTypes() {
return EMPLOYEE_TYPES;
}
public String getGivenName() {
return givenName;
}
public String getFamilyName() {
return familyName;
}
public String getType() {
return type;
}
#Override
public String toString() {
return String.format("Employee: %s, %s %s", type, givenName, familyName);
}
}