import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.*; import java.util.*; import java.text.*; public class ComboBoxDemo extends JPanel { static JFrame frame; JLabel result; String currentPattern; public ComboBoxDemo() { String[] patternExamples = { "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" }; currentPattern = patternExamples[0]; // Set up the UI for selecting a pattern. JLabel patternLabel1 = new JLabel("Enter the pattern string or"); JLabel patternLabel2 = new JLabel("select one from the list:"); patternLabel1.setAlignmentX(Component.LEFT_ALIGNMENT); patternLabel2.setAlignmentX(Component.LEFT_ALIGNMENT); JComboBox patternList = new JComboBox(patternExamples); patternList.setEditable(true); patternList.setSelectedIndex(0); patternList.setAlignmentX(Component.LEFT_ALIGNMENT); PatternListener patternListener = new PatternListener(); patternList.addActionListener(patternListener); // Create the UI for displaying result JLabel resultLabel = new JLabel("Current Date/Time", JLabel.LEFT); resultLabel.setAlignmentX(Component.LEFT_ALIGNMENT); result = new JLabel(" "); result.setForeground(Color.black); result.setAlignmentX(Component.LEFT_ALIGNMENT); result.setBorder(BorderFactory.createCompoundBorder( BorderFactory.createLineBorder(Color.black), BorderFactory.createEmptyBorder(5,5,5,5) )); // Lay out everything JPanel patternPanel = new JPanel(); patternPanel.setLayout(new BoxLayout(patternPanel, BoxLayout.Y_AXIS)); patternPanel.add(patternLabel1); patternPanel.add(patternLabel2); patternPanel.add(patternList); JPanel resultPanel = new JPanel(); resultPanel.setLayout(new GridLayout(0, 1)); resultPanel.add(resultLabel); resultPanel.add(result); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); patternPanel.setAlignmentX(Component.CENTER_ALIGNMENT); resultPanel.setAlignmentX(Component.CENTER_ALIGNMENT); add(patternPanel); add(Box.createRigidArea(new Dimension(0, 10))); add(resultPanel); setBorder(BorderFactory.createEmptyBorder(10,10,10,10)); reformat(); } // constructor /** Listens to the pattern combo box. */ class PatternListener implements ActionListener { public void actionPerformed(ActionEvent e) { JComboBox cb = (JComboBox)e.getSource(); String newSelection = (String)cb.getSelectedItem(); currentPattern = newSelection; reformat(); } } /** Formats and displays today's date. */ public void reformat() { Date today = new Date(); SimpleDateFormat formatter = new SimpleDateFormat(currentPattern); try { String dateString = formatter.format(today); result.setForeground(Color.black); result.setText(dateString); } catch (IllegalArgumentException iae) { result.setForeground(Color.red); result.setText("Error: " + iae.getMessage()); } } public static void main(String s[]) { WindowListener l = new WindowAdapter() { public void windowClosing(WindowEvent e) {System.exit(0);} }; frame = new JFrame("ComboBoxDemo"); frame.addWindowListener(l); frame.getContentPane().add("Center", new ComboBoxDemo()); frame.pack(); frame.setVisible(true); } }