[英]Why google map v2 suddenly crashed by java.lang.NullPointerException: Attempt to get length of null array?
[英]java.lang.NullPointerException for google map API v2
多年来,我一直在尝试解决此问题,但找不到问题所在。 我仅在某些运行Android 2.2的设备上遇到麻烦。 我在Android 4.1.2上进行了测试,并且工作正常。
我得到的错误:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.coldice.plotfinder/com.coldice.plotfinder.MapFragment}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2668)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2684)
at android.app.ActivityThread.access$2300(ActivityThread.java:126)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2038)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4632)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.coldice.plotfinder.MapFragment.onCreate(MapFragment.java:67)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2632)
... 11 more
所以回头看我的类MapFragment第67行
googleMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
我知道googlemap API第2版要求的API级别为12或更高,如此处所述 ,但我使用的是更低的API,因此我叫
getSupportFragmentManager();
MapFragment类代码如下:
public class MapFragment extends SherlockFragmentActivity {
private static final String TAG = "MapFragment";
private GoogleMap googleMap; // Google map
private int mapType = GoogleMap.MAP_TYPE_SATELLITE;
private Polyline polyline;; // Drawing the area of the land by using the polygon
private boolean isDrawn=false;
static String fileToBeRead =null; // The file name to be read
ArrayList<Cooridnates> cooridnatesList;
// Image utility saving
ImageSaveUtil imageUtil = new ImageSaveUtil();
@Override
public void onCreate(Bundle savedInstanceState) {
setTheme(R.style.Theme_Sherlock);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
// Different colors for each marker
float[] markerColours = {BitmapDescriptorFactory.HUE_AZURE,BitmapDescriptorFactory.HUE_BLUE,BitmapDescriptorFactory.HUE_CYAN,BitmapDescriptorFactory.HUE_GREEN,
BitmapDescriptorFactory.HUE_MAGENTA,BitmapDescriptorFactory.HUE_ORANGE,BitmapDescriptorFactory.HUE_RED,BitmapDescriptorFactory.HUE_ROSE,
BitmapDescriptorFactory.HUE_VIOLET,BitmapDescriptorFactory.HUE_YELLOW};
// The code I am getting java.lang.NullPointerException
FragmentManager fragmentManager = getSupportFragmentManager();
SupportMapFragment mapFragment = (SupportMapFragment)fragmentManager.findFragmentById(R.id.map);
googleMap = mapFragment.getMap();
googleMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
// If there is a file to be read, then read the coordinates
if(fileToBeRead!=null)
{
readData(fileToBeRead);
fileToBeRead =null;
}
// Getting the coordinates List
cooridnatesList = MainActivity.getList();
if(cooridnatesList!=null)
{
// Adding a marker from each point
for(int i=0;i<cooridnatesList.size();i++)
{
LatLng point = new LatLng(cooridnatesList.get(i).getLat(),cooridnatesList.get(i).getLon());
googleMap.addMarker(new MarkerOptions()
.position(point)
.title("My Land")
.snippet("Point: "+cooridnatesList.get(i).getLat()+","+cooridnatesList.get(i).getLon())
.icon(BitmapDescriptorFactory.defaultMarker(markerColours[i%10])));
}
googleMap.getUiSettings().setCompassEnabled(true); // Setting the compass enabled in the map
googleMap.getUiSettings().setZoomControlsEnabled(true); // Zooming is enabled
googleMap.getUiSettings().setMyLocationButtonEnabled(true); // My location button is enabled
// Zooming the camera from the first point entered
LatLng cameraLatLng = new LatLng(cooridnatesList.get(0).getLat(),cooridnatesList.get(0).getLon());
float cameraZoom = 10;
if(savedInstanceState != null){
mapType = savedInstanceState.getInt("map_type", GoogleMap.MAP_TYPE_SATELLITE);
double savedLat = savedInstanceState.getDouble("lat");
double savedLng = savedInstanceState.getDouble("lng");
cameraLatLng = new LatLng(savedLat, savedLng);
cameraZoom = savedInstanceState.getFloat("zoom",18);
}
// Setting the map type such as satellites or street view
googleMap.setMapType(mapType);
googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(cameraLatLng, cameraZoom));
//Displaying the land area
final TextView landInformation = (TextView)findViewById(R.id.textViewLandInformation);
double area = calculateArea(cooridnatesList);
landInformation.setText(getString(R.string.land_area)+"\n"+Math.round(area)+" SQ.M");
}
}
尝试将所有引用您的GoogleMap的代码移动到onStart()或onResume()。 在地图片段中的地图直到通过onCreateView( link )之后才实例化。 另外,您需要检查googleMap是否为null,因为如果未安装google play服务,或者由于其他原因无法使用地图,则它将为null。
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