多线程简单运用---时钟的实现

效果图：

 

代码：

package game;import java.awt.BorderLayout;import java.awt.Color;import java.awt.Container;import java.awt.Font;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.util.Calendar;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JMenu;import javax.swing.JMenuBar;import javax.swing.JMenuItem;import javax.swing.JOptionPane;import javax.swing.JPanel;public class ShowClock extends JFrame {Container c;JMenuBar mb;JMenu JFile,JHelp;JMenuItem mExit,mCopyright;JLabel clock;JPanel pl;public void init(){   c=this.getContentPane();   c.setLayout(new BorderLayout());   mb=new JMenuBar();   c.add(mb,BorderLayout.NORTH);      JFile=new JMenu("文件(F)");   JHelp=new JMenu("帮助(H)");   mb.add(JFile);mb.add(JHelp);   mExit=new JMenuItem("退出");   mCopyright=new JMenuItem("版权信息");   JFile.add(mExit);JHelp.add(mCopyright);      mCopyright.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){   JOptionPane.showMessageDialog(null, "本游戏由暗伤无痕出品", "版权声明", JOptionPane.INFORMATION_MESSAGE);      }   });   mExit.addActionListener(new ActionListener(){   public void actionPerformed(ActionEvent e){   ShowClock.this.dispose();   }   });   pl=new JPanel();pl.setLayout(null);   c.add(pl);   clock=new JLabel();   clock.setFont(new Font("黑体",Font.BOLD,15));       clock.setForeground(Color.blue);   pl.add(clock);   clock.setBounds(40,20,400,30);   ShowTime st=new ShowTime(clock);        st.start();   this.setSize(500,400);   this.setVisible(true);}public ShowClock(String title){super(title);init();}class ShowTime extends Thread{JLabel clock;public ShowTime(JLabel clock){this.clock=clock;}public void run(){while(true){  Calendar c=Calendar.getInstance();  int year=c.get(Calendar.YEAR);  int month=c.get(Calendar.MONTH);  int day=c.get(Calendar.DATE);  int hour=c.get(Calendar.HOUR_OF_DAY);  int minute=c.get(Calendar.MINUTE);  int second=c.get(Calendar.SECOND);  String s="北京时间   "+year+"年"+month+"月"+day+"日"+hour+"时"+minute+"分"+second+"秒";  clock.setText(s);}}}public static void main(String[] args) {    ShowClock sc=new ShowClock("时钟");}}