Updating a Scroll Pane

Question

Hi!
Im a newbie to swing so hopefully theres a simple solution to this.
Im beginning with a JScrollPane that has no data in it and is presented as such. However, when the relevant data has been selected i want to populate the scrollpane with the extracted data.
I ve started off with an empty JList that i ve instantiated in the constructor and placed in the JScrollPane. When the relevant button is pressed the list is updated with the new data, but im not sure how i can get also update scrollpane with the new list, with the results shown on screen.
Any help or code on how to do this would be much appreciated. Thanks in advance for any help.
Zidane

Answer 1

For this situation Frist u take a JScrollPane
and take a JList in the JScrollPane when the
element is added in the list it will atomaticaly
give the effect
this code help for list and Scroll Pane
Hope this will help you
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class ListDemo extends JFrame
                      implements ListSelectionListener {
    private JList list;
    private DefaultListModel listModel;
    private static final String hireString = "Hire";
    private static final String fireString = "Fire";
    private JButton fireButton;
    private JTextField employeeName;
    public ListDemo() {
        super("ListDemo");
        listModel = new DefaultListModel();
        listModel.addElement("Alison Huml");
        listModel.addElement("Kathy Walrath");
        listModel.addElement("Lisa Friendly");
        listModel.addElement("Mary Campione");
        //Create the list and put it in a scroll pane
        list = new JList(listModel);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.setSelectedIndex(0);
        list.addListSelectionListener(this);
        JScrollPane listScrollPane = new JScrollPane(list);
        JButton hireButton = new JButton(hireString);
        hireButton.setActionCommand(hireString);
        hireButton.addActionListener(new HireListener());
        fireButton = new JButton(fireString);
        fireButton.setActionCommand(fireString);
        fireButton.addActionListener(new FireListener());
        employeeName = new JTextField(10);
        employeeName.addActionListener(new HireListener());
        String name = listModel.getElementAt(
                              list.getSelectedIndex()).toString();
        employeeName.setText(name);     
        //Create a panel that uses FlowLayout (the default).
        JPanel buttonPane = new JPanel();
        buttonPane.add(employeeName);
        buttonPane.add(hireButton);
        buttonPane.add(fireButton);
        Container contentPane = getContentPane();
        contentPane.add(listScrollPane, BorderLayout.CENTER);
        contentPane.add(buttonPane, BorderLayout.SOUTH);
    class FireListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            //This method can be called only if
            //there's a valid selection
            //so go ahead and remove whatever's selected.
            int index = list.getSelectedIndex();
            listModel.remove(index);
            int size = listModel.getSize();
            if (size == 0) {
            //Nobody's left, disable firing.
                fireButton.setEnabled(false);
            } else {
            //Adjust the selection.
                if (index == listModel.getSize())//removed item in last position
                    index--;
                list.setSelectedIndex(index);   //otherwise select same index
    //This listener is shared by the text field and the hire button
    class HireListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            //User didn't type in a name...
            if (employeeName.getText().equals("")) {
                Toolkit.getDefaultToolkit().beep();
                return;
            int index = list.getSelectedIndex();
            int size = listModel.getSize();
            //If no selection or if item in last position is selected,
            //add the new hire to end of list, and select new hire.
            if (index == -1 || (index+1 == size)) {
                listModel.addElement(employeeName.getText());
                list.setSelectedIndex(size);
            //Otherwise insert the new hire after the current selection,
            //and select new hire.
            } else {
                listModel.insertElementAt(employeeName.getText(), index+1);
                list.setSelectedIndex(index+1);
    public void valueChanged(ListSelectionEvent e) {
        if (e.getValueIsAdjusting() == false) {
            if (list.getSelectedIndex() == -1) {
            //No selection, disable fire button.
                fireButton.setEnabled(false);
                employeeName.setText("");
            } else {
            //Selection, update text field.
                fireButton.setEnabled(true);
                String name = list.getSelectedValue().toString();
                employeeName.setText(name);
    public static void main(String s[]) {
        JFrame frame = new ListDemo();
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
        frame.pack();
        frame.setVisible(true);
}