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");

	}

}