这两段java实现的钟表代码有什么不同？一个运行正常 一个不正常

[javaPie]

package mvcTest;

import java.awt.*;
import java.text.DateFormat;
import java.util.*;
import javax.swing.*;
//数字时钟
public class ClockDemo extends JFrame implements Runnable
{
Thread Clock;
final int Xpoint=180;
final int Ypoint=180;
final int R=80;
int xHour=0,yHour=0,xSecond=0,ySecond=0,xMin=0,yMin=0;

public ClockDemo()
{
super("数字时钟");
setFont(new Font("宋体",Font.BOLD,20));
setSize(720,720);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);;
}
public void start()
{
if(Clock==null)
{
Clock = new Thread(this);
Clock.start();
}

}
public void run()
{
while(Clock!=null)
{
repaint();
try
{
Thread.sleep(1000);
}
catch(InterruptedException ex)
{
ex.printStackTrace();
}

}

}
public void stop()
{

Clock=null;
}
public void paint(Graphics g)
{
Graphics2D g2=(Graphics2D)g;
DateFormat dateFormat=DateFormat.getDateInstance(DateFormat.FULL);
Calendar now = new GregorianCalendar();
now.setTime(new Date());
String timeInfo="";
int hour =now.get(Calendar.HOUR_OF_DAY);
int minute=now.get(Calendar.MINUTE);
int second=now.get(Calendar.SECOND);
if(hour<=9)
timeInfo+="0"+hour+":";
else
timeInfo+=hour+":";
if(minute<=9)
timeInfo+="0"+minute+":";
else
timeInfo+=minute+":";
if(second<=9)
timeInfo+="0"+second;
else
timeInfo+=second;
g.setColor(Color.blue);
Dimension dim=getSize();
g.fillRect(0, 0, dim.width, dim.height);

g.setColor(Color.red);
g.drawString(timeInfo,130,340);
g.setColor(Color.green);
g.drawString(dateFormat.format(now.getTime()), 20, 60);
g.setColor(Color.black);
g.setFont(new Font("SAN_SERIF",Font.BOLD,15));
for(int i=0,num=12;i<360;i+=6)
{
double alfa = Math.toRadians(i);
int xPos=Xpoint+(int)(R*Math.sin(alfa));
int yPos=Ypoint-(int)(R*Math.sin(alfa));
if(i==0)
{
if(num%3==0)
g.setColor(Color.red);
else
g.setColor(Color.black);
g.drawString(""+num,xPos-5,yPos+3);
num=(num+1);
}
else
{
g.setColor(Color.black);
g.drawString(".", xPos, yPos);
}
}
g.setColor(Color.black);
g.fillOval(Xpoint-4,Ypoint-4, 8, 8);
xSecond=(int)(Xpoint+(R-10)*Math.sin(second*(2*Math.PI/60)));
ySecond=(int)(Xpoint+(R-10)*Math.sin(second*(2*Math.PI/60)));
g.setColor(Color.red);
g.drawLine(Xpoint,Ypoint,xSecond,ySecond);
//画分针
xMin=(int)(Xpoint+(R-20)*Math.sin((minute+second/60)*(2*Math.PI/60)));
yMin=(int)(Ypoint-(R-20)*Math.cos((minute+second/60)*(2*Math.PI/60)));
g.setColor(Color.red);
g.drawLine(Xpoint,Ypoint,xMin,yMin);
//画时针
xHour=(int)(Xpoint+(R-30)*Math.sin((hour+minute/60+second/60/60)*(2*Math.PI/12)));
yHour=(int)(Ypoint-(R-30)*Math.cos((hour+minute/60+second/60/60)*(2*Math.PI/12)));
g.setColor(Color.red);
g.drawLine(Xpoint,Ypoint,xHour,yHour);

}
public static void main(String[] args)
{
new ClockDemo();
}
}
--------------------------------------------------------------------------------------------------------------------------------
package lee;

import java.awt.*;
import java.text.DateFormat;
import java.util.*;
import javax.swing.*;
//数字时钟
public class ClockDemo extends JFrame implements Runnable
{
Thread clock;
final int Xpoint=180;
final int Ypoint=180;
final int R=80;
int xHour=0,yHour=0,xSecond=0,ySecond=0,xMin=0,yMin=0;
public ClockDemo()
{
super("数字时钟"); //调用父类构造函数
setFont(new Font("宋体",Font.BOLD,20)); //设置时钟的显示字体
start(); //开始进程
setSize(400,400); //设置窗口尺寸
setVisible(true); //窗口可视

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //关闭窗口时退出程序
}
public void start()
{ //开始进程
if(clock==null)//如果进程为空值
{
clock=new Thread(this); //实例化进程
clock.start(); //开始进程
}
}
public void run()//运行进程
{
while (clock!=null)
{
repaint(); //调用paint方法重绘界面
try
{
Thread.sleep(1000); //线程暂停一秒(1000毫秒)
}
catch (InterruptedException ex){
ex.printStackTrace(); //输出出错信息
}
}
}
public void stop()//停止进程
{
clock=null;
}
public void paint(Graphics g)//重载组件的paint方法
{
Graphics2D g2=(Graphics2D)g; //得到Graphics2D对象
DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.FULL);
Calendar now=new GregorianCalendar(); //实例化日历对象
now.setTime(new Date());//dateFormat.format(now.getTime())
String timeInfo=""; //输出信息
int hour=now.get(Calendar.HOUR_OF_DAY); //得到小时数
int minute=now.get(Calendar.MINUTE); //得到分数
int second=now.get(Calendar.SECOND); //得到秒数
if (hour<=9)
timeInfo+="0"+hour+":"; //格式化输出
else
timeInfo+=hour+":";
if (minute<=9)
timeInfo+="0"+minute+":";
else
timeInfo+=minute+":";
if (second<=9)
timeInfo+="0"+second;
else
timeInfo+=second;
g.setColor(Color.yellow); //设置当前颜色为白色
Dimension dim=getSize(); //得到窗口尺寸
g.fillRect(0,0,dim.width,dim.height); //填充背景色为白色
g.setColor(Color.red); //设置当前颜色为橙色
g.drawString(timeInfo,130,340); //显示时间字符串
g.setColor(Color.green);
g.drawString(dateFormat.format(now.getTime()),20,60);
g.setColor(Color.black);
// g.setFont(new Font("SAN_SERIF",Font.BOLD,15));
for(int i=0,num=12;i<360;i+=6)
{
double alfa = Math.toRadians(i);
int xPos=Xpoint+(int)(R*Math.sin(alfa));
int yPos=Ypoint-(int)(R*Math.cos(alfa));
if(i==0)
{
if (num%3==0)
g.setColor(Color.red); // 数字3,6,9,12为红色
else
g.setColor(Color.black); // 其余数字为黑色
g.drawString(""+num,xPos-5,yPos+3); // 写数字
num=(num+1);
}
else
{
g.setColor(Color.black);
g.drawString(".",xPos,yPos);
}
}
g.setColor(Color.black);
g.fillOval(Xpoint-4,Ypoint-4,10,10);
//画秒针
xSecond=(int)(Xpoint+(R-10)*Math.sin(second*(2*Math.PI/60)));
ySecond=(int)(Ypoint-(R-10)*Math.cos(second*(2*Math.PI/60)));
g.setColor(Color.red);
g.drawLine(Xpoint,Ypoint,xSecond,ySecond);
//画分针
xMin=(int)(Xpoint+(R-20)*Math.sin((minute+second/60)*(2*Math.PI/60)));
yMin=(int)(Ypoint-(R-20)*Math.cos((minute+second/60)*(2*Math.PI/60)));
g.setColor(Color.red);
g.drawLine(Xpoint,Ypoint,xMin,yMin);
//画时针
xHour=(int)(Xpoint+(R-30)*Math.sin((hour+minute/60+second/60/60)*(2*Math.PI/12)));
yHour=(int)(Ypoint-(R-30)*Math.cos((hour+minute/60+second/60/60)*(2*Math.PI/12)));
g.setColor(Color.red);
g.drawLine(Xpoint,Ypoint,xHour,yHour);
}
public static void main(String[] args)
{
new ClockDemo();
}
}