初学者关于Applet的问题，真心求教

初学者在学Applet时自己做了个显示时间的东东，动态取时间正常，可是不知为什么不能动态显示，只有applet窗口最大化、最小化或者通过拖拽边框时才会变化，用的是Eclipse运行。

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.applet.Applet;
import java.io.Console;
import java.util.Calendar;
import java.io.*;
import javax.swing.JLabel;

class Timer implements Runnable
{
String zw[]={"年","月","日","："};
StringBuffer dstr=new StringBuffer();
int y,mon,d,h,min,s;
public void getTime()
{
Calendar c1=Calendar.getInstance();
y=(c1.get(Calendar.YEAR));
mon=(c1.get(Calendar.MONTH)+1);
d=(c1.get(Calendar.DAY_OF_MONTH));
h=(c1.get(Calendar.HOUR_OF_DAY));
min=(c1.get(Calendar.MINUTE));
s=(c1.get(Calendar.SECOND));
}
public String toString(StringBuffer strBf)
{
return "当前时间是："+dstr;
}
public void run()
{
try
{
Thread.sleep(1000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
System.gc();
}

}
public class HelloDemo extends Applet {
Timer t=new Timer();
public void paint(Graphics g)
{
t.getTime();
g.setColor(Color.RED);
g.setColor(Color.ORANGE);
g.setFont(new Font("Curier",20,20));
g.drawString("当前日期是："+t.y+"年"+t.mon+"月"+t.d+"日",0,30);
g.setColor(Color.ORANGE);
g.setFont(new Font("Curier",20,20));
g.drawString("时间是："+t.h+"时"+t.min+"分"+t.s+"秒",0,50);
}
public void init()
{
this.setBackground(Color.BLACK);

}
public void start()
{
repaint();
new Thread(t).start();

}

}