JList with own data model

Question

I am trying to figure out how to use a JList correctly. I am struggling with the usage of lists in combination with my own classes/data models. My goal is to to extract the list in a separate class and change the displayed data within the list from multiple actions (Button Events / Action Listeners).

For example: If the user has chosen a compatible CSV file, the list should show the contents of that file. The file itself contains a simple playlist which is compound as follows: Artist; Title; File path

If the user adds a further song to the playlist, the list should "refresh". I've read something about "FireContents..." but I firstly would like to know how to use those lists properly.

I am going to add the relevant parts of my source code. Any help & advice are appreciated.

public class MusicTrack implements project.model.Track{
private String strArtist;
private String strTitle;
private String strFilepath;

public MusicTrack(String strArtist, String strTitle, String strFilepath){
    this.strArtist = strArtist;
    this.strTitle = strTitle;
    this.strFilepath = strFilepath;
}

MusicPlayer:

public class MusicPlayer implements ActionListener{

private JFrame mainframe;

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

/**
 * Create the application.
 */
public MusicPlayer() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    mainframe = new JFrame();
    mainframe.setTitle("MusicPlayer");
    mainframe.setBounds(100, 100, 450, 300);
    mainframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    mainframe.setLocationRelativeTo(null);

    // menu & menuitems
    JMenuBar menuBar = new JMenuBar();
    mainframe.setJMenuBar(menuBar);

    JMenu mnFile = new JMenu("Datei");
    menuBar.add(mnFile);

    JMenuItem mnItemLoadNewList = new JMenuItem("Neue Liste laden");
    mnFile.add(mnItemLoadNewList);


    JMenuItem mnItemLoadLIst = new JMenuItem("Liste laden & anhängen");
    mnFile.add(mnItemLoadLIst);

    JMenuItem mnItemSave = new JMenuItem("Speichern");
    mnFile.add(mnItemSave);

    JMenuItem mnItemNewEntry = new JMenuItem("Neuer Eintrag");
    mnFile.add(mnItemNewEntry);

    JMenu mnSort = new JMenu("Sortieren");
    menuBar.add(mnSort);

    JMenuItem mnItemArtist = new JMenuItem("nach Interpret");
    mnSort.add(mnItemArtist);

    JMenuItem mnItemTitle = new JMenuItem("nach Titel");
    mnSort.add(mnItemTitle);

    GridBagLayout gridBagLayout = new GridBagLayout();
    gridBagLayout.columnWidths = new int[]{450, 0};
    gridBagLayout.rowHeights = new int[]{227, 29, 0};
    gridBagLayout.columnWeights = new double[]{1.0, Double.MIN_VALUE};
    gridBagLayout.rowWeights = new double[]{1.0, 0.0, Double.MIN_VALUE};
    mainframe.getContentPane().setLayout(gridBagLayout);
    GridBagConstraints c = new GridBagConstraints();
    c.fill = GridBagConstraints.BOTH;


    JPanel listPanel = new JPanel();
    listPanel.setLayout(gridBagLayout);
    mainframe.getContentPane().add(listPanel);
    listPanel.setVisible(true);



    // Buttons
    JButton btnPlayAll = new JButton("Play All");
    GridBagConstraints gbc_btnPlayAll = new GridBagConstraints();
    gbc_btnPlayAll.anchor = GridBagConstraints.NORTH;
    gbc_btnPlayAll.fill = GridBagConstraints.HORIZONTAL;
    gbc_btnPlayAll.gridx = 0;
    gbc_btnPlayAll.gridy = 1;
    mainframe.getContentPane().add(btnPlayAll, gbc_btnPlayAll);

    //Action- & Eventlistener, registering individual ActionListener per Button
    mnItemLoadNewList.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            JFileChooser fChoose = new JFileChooser();
            FileNameExtensionFilter fExt = new FileNameExtensionFilter("CSV", "csv");
            fChoose.setFileFilter(fExt);
            int returnVal = fChoose.showOpenDialog(null);
            if(returnVal == JFileChooser.APPROVE_OPTION){
                JList<Track> list = new JList<Track>();
                ListModel<Track> listModel = new DefaultListModel<Track>();
                list.setModel(listModel);
                JScrollPane sPane = new JScrollPane(list);
                sPane.add(listPanel);                   
            }
        };          
    });

    // FIXME - Attach!
    mnItemLoadLIst.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            JFileChooser fChoose = new JFileChooser();
            FileNameExtensionFilter fExt = new FileNameExtensionFilter("CSV", "csv");
            fChoose.setFileFilter(fExt);
            int returnVal = fChoose.showOpenDialog(null);
            if(returnVal == JFileChooser.APPROVE_OPTION){                   

            }
        };          
    });

    // FIXME - Save!
    mnItemSave.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            JFileChooser fChoose = new JFileChooser();
            FileNameExtensionFilter fExt = new FileNameExtensionFilter("CSV", "csv");
            fChoose.setFileFilter(fExt);
            int returnVal = fChoose.showOpenDialog(null);
            if(returnVal == JFileChooser.APPROVE_OPTION){
                File selcdFile = new File(fChoose.getSelectedFile().toString());
                PlayList myPL = new PlayList();
                myPL.getTracks();
                try {
                    myPL.save(selcdFile);
                } catch (IOException e1) {
                    JOptionPane.showMessageDialog(mainframe, e1 + "\n\nBitte eine kompatible Datei wählen.", "MusicPlayer Error", JOptionPane.WARNING_MESSAGE);
                }
            }               
        };          
    });

    mnItemNewEntry.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            NewEntry myNewEntry = new NewEntry(new JFrame(), "Neuer Eintrag");
            myNewEntry.setSize(300, 240);
            myNewEntry.setLocationRelativeTo(mainframe);
            myNewEntry.setVisible(true);

        };          
    });

Class NewEntry

            // FIXME - btnChooseFile
        btnChooseFile.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                JFileChooser fChoose = new JFileChooser();
                FileNameExtensionFilter fExt = new FileNameExtensionFilter("MP3", "mp3"); // FIXME add wave etc.
                fChoose.setFileFilter(fExt);
                int returnVal = fChoose.showOpenDialog(null);
                if(returnVal == JFileChooser.APPROVE_OPTION){
                    txtFilepath.setText(fChoose.getSelectedFile().getAbsolutePath());
                }
            };          
        });

PlayList (contains simple methods such as saving, loading)

public class PlayList implements project.model.PlayList{

private List<Track> playList = new LinkedList<>();
private String strDelimiter = ";";

public void setPlayList(List<Track> playList) {
    this.playList = playList;
}

Code for JList, that still gives me headache.

        ListModel<PlayList> theModel = new DefaultListModel<PlayList>();
    JList<PlayList> myJList = new JList<PlayList>(theModel);
    for(int i = 0; i < myPlayList.getTracks().size(); i++){
        theModel.addElement(i);
    }
    JScrollPane myScrollPane = new JScrollPane(myJList);
    mainframe.add(myScrollPane);

Answer 1

You should really start by reading the official tutorial for JList, as there's quite a lot to cover. Here's the overview, though:

1. Create a list model - most of the time DefaultListModel will do.
2. Create a JList, and pass the model in the constructor (so that it uses that model).
3. Initialize the list, e.g. set the selection mode, and possibly a custom ListCellRenderer.
4. From now on, interact with the model, not the list. The model will fire the events for you.