Button ActionPerfomed move string from JList to JList

Question

I am working on an assessment for a program I would like to participate in. I am still a bit turned around on how to interpret, understand or properly use the "tutorials" located at Tutorials Point which were provided by the program.

Jlist created using Netbeans 8.1 --> JFrame Form GUI Builder

public class Window extends javax.swing.JFrame {

/**
 * Creates new form for BootcampAssessmentGui
 */
public Window() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    controlsbuttonGroup = new javax.swing.ButtonGroup();
    partsScrollPane = new javax.swing.JScrollPane();
    partsList = new javax.swing.JList<>();
    buildScrollPane = new javax.swing.JScrollPane();
    buildList = new javax.swing.JList<>();
    addButton = new javax.swing.JButton();
    removeButton = new javax.swing.JButton();
    jMenuBar1 = new javax.swing.JMenuBar();
    fileMenu = new javax.swing.JMenu();
    loadMenuItem = new javax.swing.JMenuItem();
    saveMenuItem = new javax.swing.JMenuItem();
    exitMenuItem = new javax.swing.JMenuItem();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    setTitle("Devereaux Assessment");

    partsList.setModel(new javax.swing.AbstractListModel<String>() {
        String[] strings = { "Case", "Motherboard", "CPU", "RAM", "GPU", "HDD", "PSU" };
        public int getSize() { return strings.length; }
        public String getElementAt(int i) { return strings[i]; }
    });
    partsScrollPane.setViewportView(partsList);

    buildScrollPane.setViewportView(buildList);

    addButton.setText(">>");
    addButton.setToolTipText("Add Parts to Build list");
    controlsbuttonGroup.add(addButton);
    addButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            addButtonActionPerformed(evt);
        }
    });

    removeButton.setText("<<");
    removeButton.setToolTipText("Remove Parts from Build list");
    controlsbuttonGroup.add(removeButton);
    removeButton.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            removeButtonActionPerformed(evt);
        }
    });

    fileMenu.setText("File");

    loadMenuItem.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_L, java.awt.event.InputEvent.CTRL_MASK));
    loadMenuItem.setIcon(new javax.swing.ImageIcon(getClass().getResource("/com/cooksys/assessment/arrow95.png"))); // NOI18N
    loadMenuItem.setText("Load");
    fileMenu.add(loadMenuItem);

    saveMenuItem.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_S, java.awt.event.InputEvent.CTRL_MASK));
    saveMenuItem.setIcon(new javax.swing.ImageIcon(getClass().getResource("/com/cooksys/assessment/floppy13.png"))); // NOI18N
    saveMenuItem.setText("Save");
    fileMenu.add(saveMenuItem);

    exitMenuItem.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_X, java.awt.event.InputEvent.CTRL_MASK));
    exitMenuItem.setIcon(new javax.swing.ImageIcon(getClass().getResource("/com/cooksys/assessment/exit18.png"))); // NOI18N
    exitMenuItem.setText("Exit");
    exitMenuItem.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            exitMenuItemActionPerformed(evt);
        }
    });
    fileMenu.add(exitMenuItem);

    jMenuBar1.add(fileMenu);

    setJMenuBar(jMenuBar1);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addContainerGap()
            .addComponent(partsScrollPane, javax.swing.GroupLayout.PREFERRED_SIZE, 209, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 31, Short.MAX_VALUE)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addComponent(addButton)
                .addComponent(removeButton))
            .addGap(28, 28, 28)
            .addComponent(buildScrollPane, javax.swing.GroupLayout.PREFERRED_SIZE, 209, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addContainerGap())
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                        .addComponent(buildScrollPane, javax.swing.GroupLayout.PREFERRED_SIZE, 279, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addComponent(partsScrollPane, javax.swing.GroupLayout.PREFERRED_SIZE, 279, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addGroup(layout.createSequentialGroup()
                    .addGap(125, 125, 125)
                    .addComponent(addButton)
                    .addGap(18, 18, 18)
                    .addComponent(removeButton)))
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );

    pack();
}// </editor-fold>                        

private void exitMenuItemActionPerformed(java.awt.event.ActionEvent evt) {                                             
    System.exit(0);
}                                            

private void addButtonActionPerformed(java.awt.event.ActionEvent evt) {                                          
    // add Parts to buildList
  for (Object selectedValue : partsList.getSelectedValuesList()) {
      buildList.addElement(selectedValue);
      partsList.removeElement(selectedValue);
      int  iSelected = partsList.getSelectedIndex();
      if (iSelected == -1) {
          return;
      }
    }
}                                         

private void removeButtonActionPerformed(java.awt.event.ActionEvent evt) {                                             
    // remove Parts from buildList
    for (Object selectedValue : buildList.getSelectedValuesList()) {
      partsList.addElement(selectedValue);
      buildList.removeElement(selectedValue);
      int  iSelected = buildList.getSelectedIndex();
      if (iSelected == -1) {
          return;
      }
    }
}                                            

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(Window.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(Window.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(Window.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(Window.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new Window().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JButton addButton;
private javax.swing.JList<String> buildList;
private javax.swing.JScrollPane buildScrollPane;
private javax.swing.ButtonGroup controlsbuttonGroup;
private javax.swing.JMenuItem exitMenuItem;
private javax.swing.JMenu fileMenu;
private javax.swing.JMenuBar jMenuBar1;
private javax.swing.JMenuItem loadMenuItem;
private javax.swing.JList<String> partsList;
private javax.swing.JScrollPane partsScrollPane;
private javax.swing.JButton removeButton;
private javax.swing.JMenuItem saveMenuItem;
// End of variables declaration                   
}

I am getting errors cannot find symbol - symbol: method addElement(Object) location: variable partsList type of Jlist

the error reads very straight-forward to me. My problem is most of the examples I've seen are using DefaultListModel. NetBeans is using the AbstractListModel method.

I have reviewed the following references:

http://www.java2s.com/Code/Java/Swing-JFC/DualJListwithbuttonsinbetween.htm http://docs.oracle.com/javase/tutorial/uiswing/components/list.html#scrollingapi

But I honestly feel like I am not properly understanding how these sources are to be used to debug. I feel like I am not properly using the Object --> String based on this bit of code:

 private void clearDestinationSelected() {
Object selected[] = destList.getSelectedValues();
for (int i = selected.length - 1; i >= 0; --i) {
  destListModel.removeElement(selected[i]);
}
destList.getSelectionModel().clearSelection();

}

I will be including this request for assistance in the code via comment. I'm not a cheater. I have looked, worked, searched and thought about this for a few days. At this point I feel like asking for help would be prudent.

Answer 1

The API will help you some here, since if you check out the JList API, you'll see that your compiler was right, that JList does not have an addElement(...) method, but don't lose heart -- the DefaultListModel class does have this method, and you can extract this from your JList by calling getModel() , and then call addElement(...) on the extracted model.

Edit: no good, you're using your own model derived from AbstractListModel -- you will need to make your model non-abstract -- give it a class name, and then give your Model class an addElement method. Either that or more simply, use a DefaultListModel object that you fill with your data.