小编use*_*834的帖子

大家好我想在我的谷歌地图上实现叠加.但是我在运行时收到致命错误,似乎是某种NullPointerException.当我删除"overlayList = mapView.getOverlays();"时,应用程序正常运行 和"overlayList.add(t);" 代码行.任何帮助是极大的赞赏!

主要活动:

public class CSActivity extends MapActivity implements LocationListener  {

 MapController mapController;
 MapView mapView;
 LocationManager locationManager;

MyLocationOverlay myLocationOverlay;
MyLocationOverlay compass;

private Button click_but;
private Button exit_but;
long start;
long stop;
int x,y;
GeoPoint touchedPoint;
Drawable d;
List<Overlay> overlayList;
String towers;
int lat;
int lng;

public void onCreate(Bundle bundle) {
    super.onCreate(bundle);
    setContentView(R.layout.main); // bind the layout to the activity

    click_but = new Button(this);
    click_but = (Button)findViewById(R.id.clickBtn);
    exit_but = new Button(this);
    exit_but = (Button)findViewById(R.id.exitBtn);

    d = getResources().getDrawable(R.drawable.markerblue);
    Touchy …