如何在JList上添加滚动条？ [JAVA]

Question

Ok, so here's the question. I have a JList, where the user is supposed to add some elements, and then the name of the element is displayed on a JList. I searched in all the web for adding a scroll on the JList but non of these worked. Can someone help me? This is the code of the JList, in the method 'initialize()':

 list = new JList();
        list.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {
                if (arg0.getClickCount()==2) {
                    textFieldRagioneSociale.setText(ragionesociale.get(list.getSelectedIndex()));
                    textFieldNomeAzienda.setText(nomeazienda.get(list.getSelectedIndex()));
                    textFieldIndirizzo.setText(indirizzo.get(list.getSelectedIndex()));
                    textFieldCAP.setText(CAP.get(list.getSelectedIndex()));
                    textFieldLocalita.setText(localita.get(list.getSelectedIndex()));
                    textFieldProvincia.setText(provincia.get(list.getSelectedIndex()));
                    textFieldPartitaIVA.setText(partitaiva.get(list.getSelectedIndex()));
                }
            }
        });
        frmCedamClienti.getContentPane().setLayout(null);
        list.setBounds(10, 10, 155, 255);
        frmCedamClienti.getContentPane().add(list);

Answer 1

You put the JList inside a JScrollPane.

JScrollPane scrollPane = new JScrollPane();
scrollPane.setViewportView(list);
...

Answer 2

To make it work, you should add the JList<>() to your JScrollPane() . Simple way would be as below :

    JList list = new JList(new DefaultListModel<>());

Than place your list in JScrollPane() by :

    JScrollPane scrollPane = new JScrollPane(list);

Finally, add your JScrollPane() to contentPane of your JFrame , simply by :

    contentPane.add(scrollPane);

And then, adding items to your JList<>() would look something like :

    for (int i = 0; i < 30; i++) {
        ((DefaultListModel) list.getModel()).addElement(String.valueOf(i));
    }

Here you can find full code sample:

public TestFrame() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 263, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    JList list = new JList(new DefaultListModel<>());

    JScrollPane scrollPane = new JScrollPane(list);

    scrollPane.setBounds(10, 11, 227, 239);

    contentPane.add(scrollPane);

    for (int i = 0; i < 30; i++) {
        ((DefaultListModel) list.getModel()).addElement(String.valueOf(i));
    }
}