Java 动态显示当前系统的日期、时间；如图所示：

package com.xin.test; import java.awt.Color;import java.awt.Font;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.text.SimpleDateFormat;import java.util.Date; import javax.swing.JLabel;import javax.swing.Timer;import javax.swing.JFrame; public class NowTime extends JFrame {   private static final long serialVersionUID = 4306803332677233920L;  // 添加 显示时间的JLabel public NowTime() { JLabel time = new JLabel(); time.setForeground(Color.BLUE); time.setBounds(30, 0, 900, 130); time.setFont(new Font("微软雅黑", Font.BOLD, 80)); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setLayout(null); this.setTitle("now time"); this.setBounds(500, 200, 930, 200); this.setVisible(true); this.add(time); this.setTimer(time); }  // 设置Timer 1000ms实现一次动作 实际是一个线程 private void setTimer(JLabel time) { final JLabel varTime = time; Timer timeAction = new Timer(100, new ActionListener() {  public void actionPerformed(ActionEvent e) {  long timemillis = System.currentTimeMillis();  // 转换日期显示格式  SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  varTime.setText(df.format(new Date(timemillis)));  } }); timeAction.start(); }  // 运行方法 public static void main(String[] args) { new NowTime(); } }