Adv Java - [Swing: JList Class]

♠ Posted by Unknown in Adv Java at 21:42

JList Class

List boxes are significantly different from JComboBox boxes, and not just in appearance. While a JcomboBox box drops down when you activate it, a JList occupies some fixed number of lines on a screen all the time and doesn’t change. If you want to see the items in a list, you simply call getSelectedValues(), which produces an array of String of the items that have been selected.

A JList allows multiple selection: if you control-click on more than one item (holding down the “control” key while performing additional mouse clicks) the original item stays highlighted and you can select as many as you want.

Example:

/ * <APPLET CODE = "JListExample.CLASS" WIDTH = 500 HEIGHT = 500></APPLET>

 */

 import java.awt.*;

 import javax.swing.*;

 import java.awt.event.*;

 import javax.swing.border.*;

 import javax.swing.event.*;

public class JListExample extends JApplet implements ActionListener, ListSelectionListener

{

          String[] flavors = { "Chocolate","Strawberry","Vanilla","Mint Swip"};

          DefaultListModel lItems = new DefaultListModel();

          JList lst = new JList(lItems);

          JTextArea jtf = new JTextArea(flavors.length,20);

          JButton jb = new JButton("Add Item");

         

          int count = 0;

          public void init()

          {

                   Container contentPane = getContentPane();

                   jtf.setEditable(false);

                   contentPane.setLayout(new FlowLayout());

                  

                   Border brd = BorderFactory.createMatteBorder(1,1,2,2,Color.BLACK);

                   lst.setBorder(brd);

                   jtf.setBorder(brd);

                  

                   for(int i = 0; i < 4; i++)

                             lItems.addElement(flavors[count++]);

                  

                   contentPane.add(jtf);

                   contentPane.add(lst);

                   contentPane.add(jb);

                   lst.addListSelectionListener(this);

                   jb.addActionListener(this);

          }

         

          public void valueChanged(ListSelectionEvent lse)

          {

                   jtf.setText("");

                   Object [] items = lst.getSelectedValues();

                   for(int i = 0; i < items.length; i++)

                             jtf.append(items[i] + "\n");

          }

         

          public void actionPerformed(ActionEvent ae)

          {

                   if(count < flavors.length)

                             lItems.add(0,flavors[count++]);

                   else

                             jb.setEnabled(false);

          }

}