import java.awt.Dimension;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
//第一种比较推荐：
public class TimeFrame extends JFrame
{/** Variables */private JPanel timePanel;private JLabel timeLabel;private JLabel displayArea;private String DEFAULT_TIME_FORMAT = "HH:mm:ss";private String time;private int ONE_SECOND = 1000;public TimeFrame(){timePanel = new JPanel();timeLabel = new JLabel("CurrentTime: ");displayArea = new JLabel();configTimeArea();timePanel.add(timeLabel);timePanel.add(displayArea);this.add(timePanel);this.setDefaultCloseOperation(EXIT_ON_CLOSE);this.setSize(new Dimension(200,70));this.setLocationRelativeTo(null);}/*** This method creates a timer task to update the time per second*/private void configTimeArea() {Timer tmr = new Timer();tmr.scheduleAtFixedRate(new JLabelTimerTask(),new Date(), ONE_SECOND);}/*** Timer task to update the time display area**/protected class JLabelTimerTask extends TimerTask{SimpleDateFormat dateFormatter = new SimpleDateFormat(DEFAULT_TIME_FORMAT);@Overridepublic void run() {time = dateFormatter.format(Calendar.getInstance().getTime());displayArea.setText(time);}}public static void main(String arg[]){TimeFrame timeFrame=new TimeFrame();timeFrame.setVisible(true); }
}

import java.awt.Dimension;
import java.text.SimpleDateFormat;
import java.util.Calendar;import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
//第二种
public class DTimeFrame2 extends JFrame implements Runnable{private JFrame frame;private JPanel timePanel;private JLabel timeLabel;private JLabel displayArea;private String DEFAULT_TIME_FORMAT = "HH:mm:ss";private int ONE_SECOND = 1000;public DTimeFrame2(){timePanel = new JPanel();timeLabel = new JLabel("CurrentTime: ");displayArea = new JLabel();timePanel.add(timeLabel);timePanel.add(displayArea);this.add(timePanel);this.setDefaultCloseOperation(EXIT_ON_CLOSE);this.setSize(new Dimension(200,70));this.setLocationRelativeTo(null);}public void run(){while(true){SimpleDateFormat dateFormatter = new SimpleDateFormat(DEFAULT_TIME_FORMAT);displayArea.setText(dateFormatter.format(Calendar.getInstance().getTime()));try{Thread.sleep(ONE_SECOND); }catch(Exception e){displayArea.setText("Error!!!");}} } public static void main(String arg[]){DTimeFrame2 df2=new DTimeFrame2();df2.setVisible(true);Thread thread1=new Thread(df2);thread1.start(); } }

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
import java.util.Timer;
import java.util.TimerTask;import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
//第三种：多国时钟实现
public class WorldTimeFrame extends JFrame
{/*** */private static final long serialVersionUID = 4782486524987801209L;private String time;private JPanel timePanel;private TimeZone timeZone;//时区private JComboBox zoneBox;private JLabel displayArea;private int ONE_SECOND = 1000;private String DEFAULT_FORMAT = "EEE d MMM, HH:mm:ss";public WorldTimeFrame(){zoneBox = new JComboBox();timePanel = new JPanel();displayArea = new JLabel();timeZone = TimeZone.getDefault();zoneBox.setModel(new DefaultComboBoxModel(TimeZone.getAvailableIDs()));zoneBox.addActionListener(new ActionListener(){@Overridepublic void actionPerformed(ActionEvent e) {updateTimeZone(TimeZone.getTimeZone((String) zoneBox.getSelectedItem()));}});configTimeArea();timePanel.add(displayArea);this.setLayout(new BorderLayout());this.add(zoneBox, BorderLayout.NORTH);this.add(timePanel, BorderLayout.CENTER);this.setLocationRelativeTo(null);this.setDefaultCloseOperation(EXIT_ON_CLOSE);this.setVisible(true);pack();}/*** This method creates a timer task to update the time per second*/private void configTimeArea() {Timer tmr = new Timer();tmr.scheduleAtFixedRate(new JLabelTimerTask(),new Date(), ONE_SECOND);}/*** Timer task to update the time display area**/public class JLabelTimerTask extends TimerTask{SimpleDateFormat dateFormatter = new SimpleDateFormat(DEFAULT_FORMAT, Locale.ENGLISH);@Overridepublic void run() {dateFormatter.setTimeZone(timeZone);time = dateFormatter.format(Calendar.getInstance().getTime());displayArea.setText(time);}}/*** Update the timeZone* @param newZone*/public void updateTimeZone(TimeZone newZone){this.timeZone = newZone;}public static void main(String arg[]){new WorldTimeFrame();}
}