SimpleDateFormat时钟自动更新

Question

有没有办法自动更新JPanel上的SimpleDateFormat数字时钟？

SimpleDateFormat sdf = new SimpleDateFormat("HH:mm"); 
time.setText(sdf.format(new Date())); 

如果我运行此，标签停留在剧本推出的时间...

UPDATE

我写的，到目前为止

import java.awt.*; 
import java.awt.image.BufferedImage; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
import javax.swing.*; 

public class test { 

private JFrame frame = new JFrame("Time"); 
private JPanel panel = new JPanel(); 
private JLabel time = new JLabel(); 
private JButton exit = new JButton("exit"); 
private boolean exit_bool = false; 

public test() { 
    panel.setLayout(new GridBagLayout()); 
    panel.add(time); 
    panel.add(exit); 
    panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10)); 
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); 
    frame.add(panel); 
    frame.setLocationRelativeTo(null); 
    init(true, true); 
    createHandler(); 
    startTime(); 
} 

public static void main(String[] args) { 
    EventQueue.invokeLater(new Runnable() { 

     @Override 
     public void run() { 
      test viewable = new test(); 
     } 
    }); 
} 

public void init(boolean fullscreen, boolean mouse) { 
    frame.setVisible(false); 
    frame.dispose(); 
    frame.setUndecorated(true); 
    frame.setVisible(true); 
    if(fullscreen) { 
     frame.setExtendedState(frame.MAXIMIZED_BOTH); 
    } 
    if(!mouse) { 
     frame.setCursor(java.awt.Toolkit.getDefaultToolkit().createCustomCursor(new BufferedImage(1,1,BufferedImage.TYPE_4BYTE_ABGR),new java.awt.Point(0,0),"NOCURSOR")); 
    } 
} 

public void startTime() { 
    while(!exit_bool) { 
    SimpleDateFormat sdf = new SimpleDateFormat("HH:mm"); 
    time.setText(sdf.format(new Date())); 
    } 
} 

public void createHandler() { 
    exit.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      exitActionPerformed(evt); 
     } 
    }); 
} 

private void exitActionPerformed(java.awt.event.ActionEvent evt) {           
    exit_bool = true; 
} 

} 

Answer 1

喜欢的东西会做技巧

package net.whatever; 

import javax.swing.*; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
import java.util.Timer; 
import java.util.TimerTask; 

public class Main { 
    public static void main(String[] args) { 
     JFrame frame = new JFrame(); 
     frame.setTitle("Clock"); 
     frame.setSize(200, 100); 
     frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); 
     frame.setVisible(true); 

     final JLabel label = new JLabel("", SwingConstants.CENTER); 
     label.setFont(label.getFont().deriveFont(25f)); 
     label.setSize(200, 100); 
     frame.add(label); 

     Timer timer = new Timer(); 
     timer.scheduleAtFixedRate(new TimerTask() { 
      @Override 
      public void run() { 
       String string = new SimpleDateFormat("HH:mm:ss").format(new Date()); 
       label.setText(string); 
      } 
     }, 0, 1000); 
    } 
}