Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at gui.PassengerGui$2.actionPerformed(PassengerGui.java:139)

Question

having problems with the code mentioned below. the eclipse error code is as follows ::

Any recommendations would be very much appreciated? I have have been pulling my hair out for almost one hour trying to figure out what the problem is..

private JPanel contentPane;
private JFileChooser fileChooser;
private PassengerController controller;
private PassengerTabelPanel tabelPanel;
private JTextField nameField;
private JTextField cityField;
private JTable passengerTable;
private JRadioButton  standardRadio;
private JRadioButton businessRadio;
private ButtonGroup classGroup;
private PassengerFormListener formListener;


/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                PassengerGui frame = new PassengerGui();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public PassengerGui() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 584, 368);

    JMenuBar menuBar = new JMenuBar();
    setJMenuBar(menuBar);

    JMenuItem importDataItem = new JMenuItem("Import Data");
    menuBar.add(importDataItem);

    JMenuItem exportDataItem = new JMenuItem("Export Data");
    menuBar.add(exportDataItem);

    fileChooser = new JFileChooser();
    fileChooser.addChoosableFileFilter(new PassengerFileFilter());
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    classGroup = new ButtonGroup();

    //set up class radio

            classGroup.add(standardRadio);
            classGroup.add(businessRadio);


    JLabel nameLabel = new JLabel("Name: ");
    nameLabel.setFont(new Font("Tahoma", Font.PLAIN, 14));
    nameLabel.setBounds(12, 11, 69, 31);
    contentPane.add(nameLabel);

    JLabel cityLabel = new JLabel("City: ");
    cityLabel.setFont(new Font("Tahoma", Font.PLAIN, 14));
    cityLabel.setBounds(12, 47, 69, 31);
    contentPane.add(cityLabel);

    JLabel lblNewLabel_2 = new JLabel("Class: ");
    lblNewLabel_2.setFont(new Font("Tahoma", Font.PLAIN, 14));
    lblNewLabel_2.setBounds(12, 89, 69, 31);
    contentPane.add(lblNewLabel_2);

    nameField = new JTextField();
    nameField.setBounds(60, 18, 129, 20);
    contentPane.add(nameField);
    nameField.setColumns(10);

    cityField = new JTextField();
    cityField.setColumns(10);
    cityField.setBounds(60, 53, 129, 20);
    contentPane.add(cityField);

    JRadioButton businessRadio = new JRadioButton("Business");
    businessRadio.setBounds(58, 95, 109, 23);
    contentPane.add(businessRadio);

    JRadioButton standardRadio = new JRadioButton("Standard");
    standardRadio.setBounds(60, 127, 109, 23);
    contentPane.add(standardRadio);

    JButton btnSubmit = new JButton("Submit");
    btnSubmit.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            String name = nameField.getText();
            String city = cityField.getText();
            String passengerClass = classGroup.getSelection().getActionCommand();


            PassengerFormEvent ev = new PassengerFormEvent(this, name, passengerClass, city);

@SteveSmith String passengerClass = classGroup.getSelection().getActionCommand(); — Paddy, Jun 06 '17 at 14:58
Still getting the same error feedback after adding this to the code @SteveSmith — Paddy, Jun 06 '17 at 15:18
Can you update your question with the new code. Have you created the buttongroup before you try and use it? — Steve Smith, Jun 06 '17 at 15:26
It's because the buttons you've added to the buttonGroup are also null. You need to create them before you add them. — Steve Smith, Jun 06 '17 at 15:42

coderpc · Answer 1 · 2017-06-06T15:07:06.603

1

You aren't instantiating ButtonGroup variable classGroup. You are using dot (.) operator on a null reference.

Do this:

ButtonGroup classGroup = new ButtonGroup();

and Somewhere in your code after this instantiation, do this:

String passengerClass = classGroup.getSelection().getActionCommand();

edited Jun 06 '17 at 15:07

answered Jun 06 '17 at 15:01

coderpc

2,685
3
31
58

Steve Smith · Answer 2 · 2017-06-06T15:42:34.797

0

You are not instantiating classGroup. You need code such as:-

classGroup = new ButtonGroup();

before you can call methods on classGroup.

EDIT: In answer to the second problem, it's because the buttons you've added to the buttonGroup are also null. You need to create them before you add them.

edited Jun 06 '17 at 15:42

answered Jun 06 '17 at 14:56

Steve Smith

2,008
2
14
21

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at gui.PassengerGui$2.actionPerformed(PassengerGui.java:139)

2 Answers2