为什么没有出现应有的图形

import  java.awt.*;
import  java.applet.*;
import  java.awt.event.*;
public class NoScrollPain extends Applet
{
      ScrollPane viewer; //声明了一个ScrollPane，用来封装视口和滚动杆。
      Map map;
      public void init()
      {
            viewer=new ScrollPane(ScrollPane.SCROLLBARS_AS_NEEDED);
            viewer.getHAdjustable().setUnitIncrement(5); //返回对水平滚动杆的引用。
            viewer.getHAdjustable().setBlockIncrement(50);
            viewer.getVAdjustable().setUnitIncrement(5); //返回对垂直滚动杆的引用。
            viewer.getVAdjustable().setBlockIncrement(50);
            setLayout(new BorderLayout());
            add("Center",viewer);
            map=new Map();
            viewer.add(map);
      }
}
class Map extends Canvas
{
       Map()
       {
            setSize(300,200);
       }
       public void pain(Graphics g)
       {
             g.setColor(Color.white);
             g.fillRect(0,0,300,200);
             g.setColor(Color.red);
             g.drawLine(0,100,100,100);
             g.drawLine(100,100,100,0);
             g.drawLine(125,0,125,100);
             g.drawLine(125,100,300,100);
             g.drawLine(0,125,200,125);
             g.drawLine(200,125,200,200);
             g.drawLine(225,200,225,125);
             g.drawLine(225,125,300,125);
             g.drawString("主要街道",100,120);
      }
}