How can one update and add to a JList from another JFrame?

Question

I have two JFrames.

AddSongFrame takes in the user input through jTextFields and MusicPlayerandLibraryForm updates the jList with the user input.

However, I have run into a problem with adding elements to the jList. At the line

MusicPlayerAndLibraryForm mplf = new MusicPlayerAndLibraryForm();

it seems that the JFrame is not updating the jList. It clears the jList and then adds the songName to the jList.

How can I access the JFrame in a way where it doesn't clear the jList when the user accesses another jFrame?

public class AddSongFrame extends javax.swing.JFrame {

        ArrayList<Song> songs = new ArrayList<Song>();
        ArrayList<Song> songFileLibrary = new ArrayList<Song>();
        DefaultListModel dlm = new DefaultListModel();

        int currentIndex = 0;



        public AddSongFrame() {
            initComponents();
        }


        private void jButtonBrowseFilesActionPerformed(java.awt.event.ActionEvent evt) {                                                   
           JFileChooser fileBrowser = new JFileChooser();
           fileBrowser.showOpenDialog(null);
           File f = fileBrowser.getSelectedFile();
           String fileName = f.getAbsolutePath();
           jTextFieldFileName.setText(fileName);

        }                                                  

        private void jButtonAddSongActionPerformed(java.awt.event.ActionEvent evt) {                                               

            String fileName = jTextFieldFileName.getText();
            String songName = jTextFieldSongName.getText();
            String songGenre = jTextFieldSongGenre.getText();
            String songArtist = jTextFieldArtist.getText();

            Song song = new Song(songName, fileName, songGenre, songArtist);
            Song songFiles = new Song(fileName,songName, songGenre,songArtist);
            songs.add(song);
            songFileLibrary.add(songFiles);


            updatejListMusicLibrary();

        }                                              



        private void updatejListMusicLibrary()
        {

            MusicPlayerAndLibraryForm mplf = new MusicPlayerAndLibraryForm();
            MusicPlayerAndLibraryForm.getjListMusicLibrary().setModel(dlm);
            mplf.setDlmMain(dlm);
            this.setVisible(false);
            mplf.setVisible(true);
    }

I'm not sure what the behavior you're having is, but a [mcve] might be better than the current code as we don't have access to `Song` code nor `MusicPlayerAndLibraryForm`. Please go through the [help], take the [tour] and read [ask] a good question, so your question can receive more and better answers. — Frakcool, Mar 15 '18 at 17:52
Also read [The use of multiple JFrames, good / bad practice?](https://stackoverflow.com/questions/9554636/the-use-of-multiple-jframes-good-or-bad-practice) (The general consensus is: it's bad). better to use `Dialog`s or `CardLayout` and build your GUI towards the use of `JPanel`s instead of `JFrame`s. As you're not changing the behavior of the `JFrame` and so, there's no need to `extend` it. See [extends JFrame or create it inside of class](https://stackoverflow.com/questions/22003802/extends-jframe-vs-creating-it-inside-the-program) — Frakcool, Mar 15 '18 at 17:53
The reason for the list being deleted on new `JFrame` click is that it's creating a new `List` on every click, but it's hard to tell without being able to reproduce the problem, and thus a MCVE might solve many of our doubts and point to the root of the problem and probably some minor other ones you might have — Frakcool, Mar 15 '18 at 17:55

score 1 · Accepted Answer · answered Mar 15 '18 at 18:11

Your problem is more than likely here:

MusicPlayerAndLibraryForm mplf = new MusicPlayerAndLibraryForm();

This is being called everytime you click your JButton and it create a new instance of MusicPlayerAndLibraryForm everytime.

You need to create an instance of this class only once, then use that instance to update the JList, however this line:

MusicPlayerAndLibraryForm.getjListMusicLibrary()

Tells me that getjListMusicLibrary() is a static method and shows an problem of design in your program.

However as I already said in the comments above, avoid the use of multiple JFrames and use Dialogs or a CardLayout for asking user for information and then use it to update the single instance of the JList in the JFrame. As I said, also avoid extending JFrame and create an instance of it inside your class.

score -3 · Answer 2 · answered Mar 15 '18 at 17:58

-3

You can make the list static and then create a method in your JFrame class which calls the static list and adds to it, when the button or any other thing is pressed in the JFrame...

Hope this Helps.....

answered Mar 15 '18 at 17:58

anon

7

1

static is not an answer - if the op creates more instances of the class they will more problems – MadProgrammer Mar 15 '18 at 18:44

How can one update and add to a JList from another JFrame?

2 Answers2