Java JComboBox class example

Java Swing Tutorial Explaining the JComboBox Component. JComboBox is like a drop down box — you can click a drop-down arrow and select an option from a list. It generates ItemEvent. For example, when the component has focus, pressing a key that corresponds to the first character in some entry’s name selects that entry. A vertical scrollbar is used for longer lists.

JComboBox Source Code

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class JComboBoxDemo extends JPanel { JLabel jlbPicture; public JComboBoxDemo() { String[] comboTypes = { "Numbers", "Alphabets", "Symbols" }; // Create the combo box, and set 2nd item as Default JComboBox comboTypesList = new JComboBox(comboTypes); comboTypesList.setSelectedIndex(2); comboTypesList.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { JComboBox jcmbType = (JComboBox) e.getSource(); String cmbType = (String) jcmbType.getSelectedItem(); jlbPicture.setIcon(new ImageIcon("" + cmbType.trim().toLowerCase() + ".jpg")); } }); // Set up the picture jlbPicture = new JLabel(new ImageIcon("" + comboTypes[comboTypesList.getSelectedIndex()] + ".jpg")); jlbPicture.setBorder(BorderFactory.createEmptyBorder(10, 0, 0, 0)); jlbPicture.setPreferredSize(new Dimension(177, 122 + 10)); // Layout the demo setLayout(new BorderLayout()); add(comboTypesList, BorderLayout.NORTH); add(jlbPicture, BorderLayout.SOUTH); setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20)); } public static void main(String s[]) { JFrame frame = new JFrame("JComboBox Usage Demo"); frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); frame.setContentPane(new JComboBoxDemo()); frame.pack(); frame.setVisible(true); } }

 Output

Download JComboBox Source Code

Another Example: JComboBox Source Code

import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.*; import java.util.*; import java.text.*; public class DateComboBoxDemo extends JPanel { static JFrame frame; JLabel jlbResult; String datePattern_Current; public DateComboBoxDemo() { String[] datePatterns = { "dd MMMMM yyyy", "dd.MM.yy", "MM/dd/yy", "yyyy.MM.dd G 'at' hh:mm:ss z", "EEE, MMM d, ''yy", "h:mm a", "H:mm:ss:SSS", "K:mm a,z", "yyyy.MMMMM.dd GGG hh:mm aaa" }; datePattern_Current = datePatterns[0]; // Set up the UI for selecting a pattern. JLabel jlbHeading = new JLabel( "Enter Date pattern /Select from list:"); JComboBox patternList = new JComboBox(datePatterns); patternList.setEditable(true); patternList.setAlignmentX(Component.LEFT_ALIGNMENT); patternList.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { JComboBox jcmbDates = (JComboBox) e.getSource(); String seletedDate = (String) jcmbDates.getSelectedItem(); datePattern_Current = seletedDate; showDateinLabel(); } }); // Create the UI for displaying result JLabel jlbResultHeading = new JLabel("Current Date/Time", JLabel.LEFT); jlbResult = new JLabel(" "); jlbResult.setForeground(Color.black); jlbResult.setBorder(BorderFactory.createCompoundBorder( BorderFactory.createLineBorder(Color.black), BorderFactory .createEmptyBorder(5, 5, 5, 5))); // Lay out everything JPanel jpnDate = new JPanel(); jpnDate.setLayout(new BoxLayout(jpnDate, BoxLayout.Y_AXIS)); jpnDate.add(jlbHeading); jpnDate.add(patternList); JPanel jpnResults = new JPanel(); jpnResults.setLayout(new GridLayout(0, 1)); jpnResults.add(jlbResultHeading); jpnResults.add(jlbResult); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); jpnDate.setAlignmentX(Component.LEFT_ALIGNMENT); jpnResults.setAlignmentX(Component.LEFT_ALIGNMENT); add(jpnDate); add(Box.createRigidArea(new Dimension(0, 10))); add(jpnResults); setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10)); showDateinLabel(); } // constructor /** Formats and displays today's date. */ public void showDateinLabel() { Date today = new Date(); SimpleDateFormat formatter = new SimpleDateFormat( datePattern_Current); try { String dateString = formatter.format(today); jlbResult.setForeground(Color.black); jlbResult.setText(dateString); } catch (IllegalArgumentException e) { jlbResult.setForeground(Color.red); jlbResult.setText("Error: " + e.getMessage()); } } public static void main(String s[]) { frame = new JFrame("JComboBox Usage Demo"); frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); frame.setContentPane(new DateComboBoxDemo()); frame.pack(); frame.setVisible(true); } }

Output

Download JComboBox Source Code

Java JComboBox Hierarchy

javax.swing
Class JComboBox 
java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JComponent
javax.swing.JComboBox
All Implemented Interfaces: 
Accessible, ActionListener, EventListener, ImageObserver, ItemSelectable, ListDataListener, MenuContainer, Serializable

JComboBox Constructor

JComboBox()
Creates a JComboBox with a default data model.

JComboBox(ComboBoxModel aModel)
Creates a JComboBox that takes it’s items from an existing ComboBoxModel.

JComboBox(Object[] items)
Creates a JComboBox that contains the elements in the specified array.

JComboBox(Vector items)
Creates a JComboBox that contains the elements in the specified Vector.