谷歌地圖圖釘錯誤

Question

我想顯示地圖上的特定位置，以及我想放置圖釘通知的那個特定位置。我已經嘗試了下面的代碼，但它顯示空指針例外，請幫我添加標記。

public class MapDemoActivity extends MapActivity { 
MapView mapView; 
MapController mc; 
GeoPoint p; 
class MapOverlay extends com.google.android.maps.Overlay 
    { 
     @Override 
     public boolean draw(Canvas canvas, MapView mapView, 
     boolean shadow, long when) 
     { 
      super.draw(canvas, mapView, shadow);     

      //---translate the GeoPoint to screen pixels--- 
      Point screenPts = new Point(); 
      mapView.getProjection().toPixels(p, screenPts); 

      //---add the marker--- 
      Bitmap bmp = BitmapFactory.decodeResource(
       getResources(), R.drawable.pushpin);    
      canvas.drawBitmap(bmp, screenPts.x, screenPts.y-50, null);   
      return true; 
     } 
    } 

public void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     mapView = (MapView) findViewById(R.id.mapView); 

     mapView.setBuiltInZoomControls(true); 
     mc.animateTo(p); 
     mc.setZoom(17); 

     //---Add a location marker--- 
     MapOverlay mapOverlay = new MapOverlay(); 
     List<Overlay> listOfOverlays = mapView.getOverlays(); 
     listOfOverlays.clear(); 
     listOfOverlays.add(mapOverlay);   

     mapView.invalidate(); 

    } 
@Override 
protected boolean isRouteDisplayed() { 
    // TODO Auto-generated method stub 
    return false; 
} 

Answer 1

此鏈接可能對你有用

https://github.com/commonsguy/cw-advandroid/tree/master/Maps/NooYawkTouch/

Answer 2

嘗試使用GoogleMap.addMarker(markerOptions);在Markers of Google Maps Android API

描述，那麼你可以使用MapView類的setOnMarkerClickListener這樣的：

mapView.setOnMarkerClickListener(new OnMarkerClickListener() { 
    @Override boolean onMarkerClick(Marker marker) { 
     // marker clicked 
    } 
});