JList(add/remove) celosan primer

Code:

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.ListIterator;

import javax.swing.AbstractListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.event.MouseInputAdapter;

public class Sortiranje {
    List<String> imena;
    JList listaImena;
    JButton dugmeSortiraj;
    JFrame prozor;
    
    JPopupMenu popupMenu;
    JMenuItem itemDodajIme;
    JMenuItem itemUkloniIme;
    
    class MyListModel extends AbstractListModel {
        static final long serialVersionUID = 1L;
        
        public Object getElementAt(int i) {
            return imena.get(i);
        }
        
        public void addElement(String ime) {
            imena.add(ime);
            super.fireIntervalAdded(this, imena.size() - 1, imena.size() - 1);
        }
        
        public void removeElement(int index) {
            imena.remove(index);
            super.fireIntervalRemoved(this, index, index);
        }
        
        public int getSize() {
            return imena.size();
        }        
    }

    void kreirajIPrikaziGUI() {
        upisiPodrazumevanaImena();
        
        prozor = new JFrame("JList Demonstracija - Sortiranje");
        prozor.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        prozor.setPreferredSize(new Dimension(200, 300));
        
        prozor.setLayout(new BorderLayout());
        
        listaImena = new JList(new MyListModel());
        
        prozor.add(new JScrollPane(listaImena), BorderLayout.CENTER);
            
        dugmeSortiraj = new JButton("Sortiraj");
        dugmeSortiraj.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                sortirajImena();
                listaImena.repaint();
            }
        });
        prozor.add(dugmeSortiraj, BorderLayout.PAGE_END);
        
        popupMenu = new JPopupMenu();

        itemDodajIme = new JMenuItem("Dodaj ime");
        popupMenu.add(itemDodajIme);
        
        listaImena.addMouseListener(new MouseInputAdapter(){
            @Override
            public void mouseReleased(MouseEvent event) {
                if (event.isPopupTrigger()) {
                    popupMenu.show(listaImena, event.getX(), event.getY());
                }
            }
        }
        );
        
        itemUkloniIme = new JMenuItem("Ukloni ime");
        popupMenu.add(itemUkloniIme);
        itemDodajIme.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                String ime = JOptionPane.showInputDialog("Unesi ime");
                MyListModel model = (MyListModel)listaImena.getModel(); 
                model.addElement(ime);
            }
        });
        
        itemUkloniIme.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                int index = listaImena.getSelectedIndex();
                if (index == -1) {
                    JOptionPane.showMessageDialog(null, "Morate selektovati element u listi", "Greska", JOptionPane.ERROR_MESSAGE);
                } else {
                    MyListModel model = (MyListModel)listaImena.getModel(); 
                    model.removeElement(index);
                }
            }
        });
        
        
        prozor.pack();
        prozor.setVisible(true);
    }
    
    void sortirajImena() {
        Collections.sort(imena, 
                new Comparator<String>() {        
                    public int compare(String osobaA, String osobaB) {
                        String[] deloviA = osobaA.split(" ");
                        String[] deloviB = osobaB.split(" ");
                        
                        if (deloviA[1].compareTo(deloviB[1]) < 0)
                            return -1;
                        
                        if (deloviA[1].compareTo(deloviB[1]) > 0)
                            return 1;
                        
                        return deloviA[0].compareTo(deloviB[0]);
                    }
                }
            );        
    }

    void upisiPodrazumevanaImena() {
        imena = new ArrayList<String>();
        imena.add("Pera Peric");
        imena.add("Ana Anic");
        imena.add("Mika Mikic"); 
        imena.add("Pera Mikic");
        imena.add("Mika Peric");
        imena.add("Mika Anic");
    }

    void testirajSortiranje() {
        upisiPodrazumevanaImena();
        sortirajImena();
        ispisiImena();
    }
    
    private void ispisiImena() {
            ListIterator<String> i = imena.listIterator(imena.size());
            while (i.hasPrevious())
                System.out.println(i.previous());
    }
    
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                Sortiranje sortiranje = new Sortiranje();
                sortiranje.kreirajIPrikaziGUI();
            }
        });
    }
}