The examples described in this article can realize Java's dynamic display of time on the interface. The specific implementation methods are summarized as follows:
1. Method 1 uses TimerTask:
Use java.util.Timer and java.util.TimerTask for dynamic updates. After all, each update can be regarded as occurring once every 1 second.
The code is as follows:
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;/** * This class is a simple JFrame implementation to explain how to * display time dynamically on the JSwing-based interface. * @author Edison * */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); @Override public void run() { time = dateFormatter.format(Calendar.getInstance().getTime()); displayArea.setText(time); } } public static void main(String arg[]) { TimeFrame timeFrame=new TimeFrame(); timeFrame.setVisible(true); } }
Inherit TimerTask to create a custom task, get the current time, and update displayArea.
Then create an instance of timer and execute timertask every 1 second. Since there may be time errors when using schedule, the higher-precision scheduleAtFixedRate is called directly.
2. Method 2: Using threads:
This one is relatively simple. The specific code is as follows:
import java.awt.Dimension;import java.text.SimpleDateFormat;import java.util.Calendar;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;/** * This class is a simple JFrame implementation to explain how to * display time dynamically on the JSwing-based interface. * @author Edison * */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(); } }Compare:
Personally, I prefer method one, because Timer can be shared by multiple TimerTasks, and generating a thread will increase the maintenance complexity of multi-threads.
Pay attention to the following code:
jFrame.setDefaultCloseOperation(); // Add specific behavior to the close button jFrame.setLocationRelativeTo(null); // Make the Frame appear in the middle of the screen instead of the upper left.
By slightly modifying the above method, you can display the time in multiple countries. The code is as follows:
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;/** * A simple world clock * @author Edison * */public class WorldTimeFrame extends JFrame{ /** * */ private static final long serialVersionUID = private String time; private JPanel timePanel; private TimeZone timeZone; 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(){ @Override public 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); @Override public 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(); } }Originally, the displayArea needs to be updated in updateTimeZone(TimeZone newZone). However, considering that the execution time of TimerTask is too short, only 1 second, to the naked eye, it is basically the same as updating immediately. If the execution time of TimerTask is long, the displayArea should be updated immediately and carefully.
Replenish:
①. pack() is used to automatically calculate the screen size;
②. TimeZone.getAvailableIDs() is used to obtain all TimeZone.