import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.*; import java.util.*; import java.text.SimpleDateFormat; /** * <p>Title: ComboBox下拉域演示</p> * <p>Description: 通过选择或这输入一种日期格式来格式化今天的日期</p> * <p>Copyright: Copyright (c) 2014</p> * <p>Filename: ComboBoxDemo.java</p> * @author 王海涛 * @version 0.1 */ public class ComboBoxDemo extends JPanel implements ActionListener { static JFrame frame; JLabel result; String currentPattern; /** *<br>方法说明:构造器。 初始化窗口构件 *<br>输入參数: *<br>返回类型: */ public ComboBoxDemo() { setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS)); 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]; //设置一个规范的用户界面 JLabel patternLabel2 = new JLabel("从下拉列表中选择一种:"); JComboBox patternList = new JComboBox(patternExamples); patternList.addActionListener(this);//patternList的监视器是这个面板 patternList.setForeground(Color.yellow); //创建一个显示结果用户界面 JLabel resultLabel = new JLabel("当前 日期/时间", JLabel.LEADING);//相当于LEFT result = new JLabel(); result.setForeground(Color.black); result.setBorder(BorderFactory.createCompoundBorder( BorderFactory.createLineBorder(Color.cyan), BorderFactory.createEmptyBorder(7,7,7,7) )); //布置构件 JPanel patternPanel = new JPanel(); patternPanel.setLayout(new BoxLayout(patternPanel, BoxLayout.PAGE_AXIS)); patternPanel.add(patternLabel2); patternList.setAlignmentX(Component.LEFT_ALIGNMENT); patternPanel.add(patternList); JPanel resultPanel = new JPanel(new GridLayout(2, 1));//新建一个网格视图的面板 resultPanel.add(resultLabel); resultPanel.add(result); patternPanel.setAlignmentX(Component.LEFT_ALIGNMENT); resultPanel.setAlignmentX(Component.LEFT_ALIGNMENT); add(patternPanel); add(Box.createRigidArea(new Dimension(0, 10))); add(resultPanel); setBorder(BorderFactory.createEmptyBorder(20,20,20,20)); reformat(); } /** *<br>方法说明:事件处理 *<br>输入參数: *<br>返回类型: */ public void actionPerformed(ActionEvent e) { //patternList监视器 JComboBox cb = (JComboBox)e.getSource(); String newSelection = (String)cb.getSelectedItem(); currentPattern = newSelection; reformat(); } /** *<br>方法说明:格式和显示今天的日期 *<br>输入參数: *<br>返回类型: */ public void reformat() { Date today = new Date(); SimpleDateFormat formatter = new SimpleDateFormat(currentPattern); try { String dateString = formatter.format(today); result.setForeground(Color.red); result.setText(dateString); } catch (IllegalArgumentException iae) { result.setForeground(Color.red); result.setText("Error: " + iae.getMessage()); } } /** *<br>方法说明:主方法 *<br>输入參数: *<br>返回类型: */ public static void main(String[] args) { JFrame.setDefaultLookAndFeelDecorated(true); //创建一个窗口 frame = new JFrame("ComboBox"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //创建一个面版容器 JComponent newContentPane = new ComboBoxDemo(); newContentPane.setOpaque(true); frame.setContentPane(newContentPane); frame.setForeground(Color.cyan); //显示窗口 frame.pack(); frame.setVisible(true); } }
时间: 2024-10-11 12:26:09