JList در جاوا (Swing Graphic in Java)

public class ListExample {
     ListExample() {
          JFrame f = new JFrame();
          DefaultListModel<String> l1 = new DefaultListModel<>();
          l1.addElement("Item1");
          l1.addElement("Item2");
          l1.addElement("Item3");
          l1.addElement("Item4");
          JList<String> list = new JList<>(l1);
          list.setBounds(100, 100, 75, 75);
          f.add(list);
          f.setSize(400, 400);
          f.setLayout(null);
          f.setVisible(true);
     }

     public static void main(String args[]) {
          new ListExample();
     }
}

public class ListExample {
     ListExample() {
          JFrame f = new JFrame();
          final JLabel label = new JLabel();
          label.setSize(500, 100);
          JButton b = new JButton("Show");
          b.setBounds(200, 150, 80, 30);
          final DefaultListModel<String> l1 = new DefaultListModel<>();
          l1.addElement("C");
          l1.addElement("C++");
          l1.addElement("Java");
          l1.addElement("PHP");
          final JList<String> list1 = new JList<>(l1);
          list1.setBounds(100, 100, 75, 75);
          DefaultListModel<String> l2 = new DefaultListModel<>();
          l2.addElement("Turbo C++");
          l2.addElement("Struts");
          l2.addElement("Spring");
          l2.addElement("YII");
          final JList<String> list2 = new JList<>(l2);
          list2.setBounds(100, 200, 75, 75);
          f.add(list1);
          f.add(list2);
          f.add(b);
          f.add(label);
          f.setSize(450, 450);
          f.setLayout(null);
          f.setVisible(true);
          b.addActionListener(new ActionListener() {
              public void actionPerformed(ActionEvent e) {
                   String data = "";
                   if (list1.getSelectedIndex() != -1) {
                        data = "Programming language Selected: "
                                  + list1.getSelectedValue();
                        label.setText(data);
                   }
                   if (list2.getSelectedIndex() != -1) {
                        data += ", FrameWork Selected: ";
                        for (Object frame : list2.getSelectedValuesList()) {
                             data += frame + " ";
                        }
                   }
                   label.setText(data);
              }
          });
     }

     public static void main(String args[]) {
          new ListExample();
     }
}