Adv Java - [Swing: JComboBox Class]

♠ Posted by Unknown in Adv Java at 20:49

JComboBox Class

Swing provides a combo box (a combination of a text field and a drop-down list) through the JComboBox class, which extends JComponent. A combo box normally displays one entry. However, it can also display a drop-down list that allows a user to select a different entry. You can also type your selection into the text field.
Two of JComboBox’s constructors are show here:

     JComboBox()

     JComboBox(Vector v)

Items are added to the list of choices via the addItem() method, whose signature is show here:

    

     void addItem(Object obj)

Example:

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

 */

 import java.awt.*;

 import java.awt.event.*;

 import javax.swing.*;

public class JComboboxExample extends JApplet implements ItemListener

{

          JLabel jl;

          public void init()

          {

                   Container contentPane = getContentPane();

                   contentPane.setLayout(new FlowLayout());

                  

                   JComboBox jc = new JComboBox();

                   jc.addItem("Java Logo");

                   jc.addItem("Winxp Logo");

                   jc.addItem("Green Logo");

                   jc.addItem("Red Logo");

                   jc.addItemListener(this);

                   contentPane.add(jc);

                  

                   jl = new JLabel(new ImageIcon("c:\\PracticeJava\\javalogo.gif"));

                   contentPane.add(jl);

          }

         

          public void itemStateChanged(ItemEvent ie)

          {

                   String s = (String)ie.getItem();

                   if(s == "Java Logo")

                   {

                             jl.setIcon(new ImageIcon("C:\\PracticeJava\\javalogo.gif"));

                   }

                   else if(s == "Windxp Logo")

                   {

                             jl.setIcon(new ImageIcon("C:\\PracticeJava\\winxp.gif"));

                   }

                   else if(s == "Green Logo")

                   {

                             jl.setIcon(new ImageIcon("C:\\PracticeJava\\greenshd.gif"));

                   }

                   else

                   {

                             jl.setIcon(new ImageIcon("C:\\PracticeJava\\redshd.gif"));

                   }

          }

}