这个滚动条小应用程序哪里错了？

import  java.awt.*;
import  java.applet.*;
import  java.awt.event.*;
public class ScrollbarSlider extends Applet implements AdjustmentListener
{
      Scrollbar slider;
      TextField value;
      public void init()
      {
            setLayout(new BorderLayout()); //设置小应用程序的布局为BorderLayout。
            slider=new Scrollbar(Scrollbar.HORIZONTAL,100,1,0,200);
              //构造了一个水平的滚动杆。
            slider.setUnitIncrement(1);
            slider.setBlockIncrement(25);
            add("南",slider);
            value=new TextField("100",5);
            Panel p=new Panel();
            add("中心",p);
            p.add(value);
            slider.addAdjustmentListener(this);
     }
     public void adjustmentValueChanged(AdjustmentEvent e)
     {
           if(e.getAdjustable()==slider)
           {
                value.setText(new Integer(e.getValue()).toString());
           }
     }
}