MapView中PinPoint上的OnTap

Question

我有一个mapview，我在其中添加了引脚。

以下是CustomPinPoint类：

   public class CustomPinpoint extends ItemizedOverlay<OverlayItem>{


private ArrayList<OverlayItem> pinpoints = new ArrayList<OverlayItem>();
private Context c;


public CustomPinpoint(Drawable defaultMarker) {
    super(boundCenter(defaultMarker));
    // TODO Auto-generated constructor stub
}
public CustomPinpoint(Drawable m, Context context) {
    // TODO Auto-generated constructor stub
    this(m);
    c = context;
}

@Override
protected OverlayItem createItem(int i) {
    // TODO Auto-generated method stub
    return pinpoints.get(i);
}

@Override
public int size() {
    // TODO Auto-generated method stub
    return pinpoints.size();
}

public void insertPinpoint(OverlayItem item){
    pinpoints.add(item);
    this.populate();
}
  }

这就是我添加引脚的方式：

   Touchy t = new Touchy();
   overlayList = map.getOverlays();
   overlayList.add(t);
   compass = new MyLocationOverlay(Map.this, map);
   overlayList.add(compass);
   controller = map.getController();
   OverlayItem overlayItem = new OverlayItem(ourLocation, "What's up", "2nd String");
   CustomPinpoint custom = new CustomPinpoint(d, Map.this);
   custom.insertPinpoint(overlayItem);
   overlayList.add(custom); 

一切都很好，但我不知道当我敲击别针时我怎么能出现气球（或其他类）。我有一个包含每个引脚描述的数据库，因此我需要在引脚上每次点击都显示描述。