5楼的代码,最好改一下,不怕一万就怕万一 吗!

//开头去掉implements

SwingUtilities.invokeLater( new Runnable(){
public void run(){
while(true){
try{
Thread.sleep(1000);
}
catch(InterruptedException ie){
ie.printStackTrace();
}
jl.setText(df.format(new Date()));
repaint();
}

}
}