我想在地图的起点设置一个标记。 但getResource给出错误，下面是代码。请帮忙。 最后使用getResources（），请参阅底部 包infy.route;
public class MapRouteActivity extends MapActivity {
MapView mapView;
private Road mRoad;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.routeplanning);
mapView = (MapView) findViewById(R.id.mapview);
mapView.setBuiltInZoomControls(true);
Bundle extras = this.getIntent().getExtras();
String fLat=extras.getString("fromLat");
String fLong=extras.getString("fromLong");
String tLat=extras.getString("toLat");
String tLong=extras.getString("toLong");
final double fromLat=Double.parseDouble(fLat);
final double fromLon=Double.parseDouble(fLong);
final double toLat=Double.parseDouble(tLat);
final double toLon=Double.parseDouble(tLong);
new Thread()
{
@Override
public void run()
{
//double fromLat = 28.6353, fromLon = 77.2250, toLat = 30.7313, toLon = 76.7754;
/***url contains the path to fetch the kml file from the internet*/
String url = RoadProvider
.getUrl(fromLat, fromLon, toLat, toLon);
InputStream is = getConnection(url);
mRoad = RoadProvider.getRoute(is);
mHandler.sendEmptyMessage(0);
}
}.start();
}
Handler mHandler = new Handler()
{
public void handleMessage(android.os.Message msg)
{
TextView textView = (TextView) findViewById(R.id.description);
textView.setText(mRoad.mName + " " + mRoad.mDescription);
MapOverlay mapOverlay = new MapOverlay(mRoad, mapView);
List<Overlay> listOfOverlays = mapView.getOverlays();
listOfOverlays.clear();
listOfOverlays.add(mapOverlay);
mapView.invalidate();
};
};
private InputStream getConnection(String url) {
InputStream is = null;
try {
//Opens a connection to the remote database(bidirectional)
URLConnection conn = new URL(url).openConnection();
is = conn.getInputStream();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return is;
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
}
class MapOverlay extends com.google.android.maps.Overlay {
Road mRoad;
ArrayList<GeoPoint> mPoints;
Drawable greenMarker;
Drawable finishMarker;
HelloItemizedOverlay itemizedOverlay;
List<Overlay> mapOverlays;
LinearLayout linearLayout;
public MapOverlay(Road road, MapView mv) {
mRoad = road;
if (road.mRoute.length > 0)
{
mPoints = new ArrayList<GeoPoint>();
for (int i = 0; i < road.mRoute.length; i++)
{
mPoints.add(new GeoPoint((int) (road.mRoute[i][1] * 1000000),
(int) (road.mRoute[i][0] * 1000000)));
}
int moveToLat = (mPoints.get(0).getLatitudeE6() + (mPoints.get(
mPoints.size() - 1).getLatitudeE6() - mPoints.get(0)
.getLatitudeE6()) / 2);
int moveToLong = (mPoints.get(0).getLongitudeE6() + (mPoints.get(
mPoints.size() - 1).getLongitudeE6() - mPoints.get(0)
.getLongitudeE6()) / 2);
GeoPoint moveTo = new GeoPoint(moveToLat, moveToLong);
MapController mapController = mv.getController();
mapController.animateTo(moveTo);
mapController.setZoom(7);
}
}
@Override
public boolean draw(Canvas canvas, MapView mv, boolean shadow, long when) {
super.draw(canvas, mv, shadow);
drawPath(mv, canvas);
return true;
}
public void drawPath(MapView mv, Canvas canvas) {
greenMarker = getResources().getDrawable(R.drawable.greenmarker);
int x1 = -1, y1 = -1, x2 = -1, y2 = -1;
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(3);
mapOverlays = mv.getOverlays();
itemizedOverlay = new HelloItemizedOverlay(greenMarker);
for (int i = 0; i < mPoints.size(); i++) {
Point point = new Point();
mv.getProjection().toPixels(mPoints.get(i), point);
if(i == 0){
OverlayItem overlayitem = new OverlayItem(mPoints.get(0), "", "");
itemizedOverlay.addOverlay(overlayitem);
mapOverlays.add(itemizedOverlay);
}
x2 = point.x;
y2 = point.y;
if (i > 0) {
canvas.drawLine(x1, y1, x2, y2, paint);
}
x1 = x2;
y1 = y2;
}
}
}
这是堆栈跟踪 在第174行，我使用getResource（）和168调用drawpath（）完成
02-23 23:20:20.960: ERROR/AndroidRuntime(804): java.lang.NullPointerException
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at infy.route.MapOverlay.drawPath(MapRouteActivity.java:174)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at infy.route.MapOverlay.draw(MapRouteActivity.java:168)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at com.google.android.maps.OverlayBundle.draw(OverlayBundle.java:42)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at com.google.android.maps.MapView.onDraw(MapView.java:476)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.View.draw(View.java:6274)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.drawChild(ViewGroup.java:1526)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.drawChild(ViewGroup.java:1524)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.View.draw(View.java:6277)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.widget.FrameLayout.draw(FrameLayout.java:352)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.drawChild(ViewGroup.java:1526)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.drawChild(ViewGroup.java:1524)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1256)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.View.draw(View.java:6277)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.widget.FrameLayout.draw(FrameLayout.java:352)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1883)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewRoot.draw(ViewRoot.java:1332)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewRoot.performTraversals(ViewRoot.java:1097)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.view.ViewRoot.handleMessage(ViewRoot.java:1613)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.os.Handler.dispatchMessage(Handler.java:99)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.os.Looper.loop(Looper.java:123)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at android.app.ActivityThread.main(ActivityThread.java:4203)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at java.lang.reflect.Method.invokeNative(Native Method)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at java.lang.reflect.Method.invoke(Method.java:521)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
02-23 23:20:20.960: ERROR/AndroidRuntime(804): at dalvik.system.NativeStart.main(Native Method)
（编辑：重新格式化的代码）
答案 0 :(得分：3)
叠加没有资源。传递对Context的引用（即Activity），并在其上调用getResources（）。
相关问题：Android getResource() undefined error
编辑：
更改
MapOverlay mapOverlay = new MapOverlay(mRoad, mapView);
到
MapOverlay mapOverlay = new MapOverlay(MapRouteActivity.this, mRoad, mapView);
和
public MapOverlay(Road road, MapView mv) {
到
Context context;
public MapOverlay(Context context, Road road, MapView mv) {
this.context = context;
最后，将调用更改为context.getResources（）。getDrawable（...