google map API v2的java.lang.NullPointerException
多年来我一直在努力解决这个问题,但我找不到问题所在。 我只在一些运行安卓2.2的设备上遇到了问题。我在安卓4.1.2上进行了测试,效果很好 我得到的错误是:google map API v2的java.lang.NullPointerException,java,android,nullpointerexception,google-maps-android-api-2,Java,Android,Nullpointerexception,Google Maps Android Api 2,多年来我一直在努力解决这个问题,但我找不到问题所在。 我只在一些运行安卓2.2的设备上遇到了问题。我在安卓4.1.2上进行了测试,效果很好 我得到的错误是: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.coldice.plotfinder/com.coldice.plotfinder.MapFragment}: java.lang.NullPointerException at android.ap
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
回顾一下我的类MapFragment第67行
googleMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE);
我知道GoogleMapAPIv2需要12级或更高的API,但我使用的是更低的API,所以我调用了
getSupportFragmentManager();
MapFragment类代码如下所示:
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");
}
}
公共类MapFragment扩展了SherlockFragmentActivity{
私有静态最终字符串TAG=“MapFragment”;
私有谷歌地图谷歌地图;//谷歌地图
私有int-mapType=GoogleMap.MAP\u-TYPE\u卫星;
专用多段线多段线;;//使用多边形绘制土地面积
私有布尔值isDrawn=false;
静态字符串fileToBeRead=null;//要读取的文件名
ArrayList CooridesList;
//图像实用程序保存
ImageSaveUtil imageUtil=新的ImageSaveUtil();
@凌驾
创建时的公共void(Bundle savedInstanceState){
setTheme(R.style.Theme_Sherlock);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_map);
//每个标记的颜色不同
float[]MarkerColor={BitmapDescriptorFactory.HUE_AZURE,BitmapDescriptorFactory.HUE_蓝色,BitmapDescriptorFactory.HUE_青色,BitmapDescriptorFactory.HUE_绿色,
BitmapDescriptorFactory.HUE_洋红,BitmapDescriptorFactory.HUE_橙色,BitmapDescriptorFactory.HUE_红色,BitmapDescriptorFactory.HUE_玫瑰色,
BitmapDescriptorFactory.HUE_VIOLET,BitmapDescriptorFactory.HUE_YELLOW};
//我得到的代码是java.lang.NullPointerException
FragmentManager FragmentManager=getSupportFragmentManager();
SupportMapFragment mapFragment=(SupportMapFragment)fragmentManager.findFragmentById(R.id.map);
googleMap=mapFragment.getMap();
googleMap.setMapType(googleMap.MAP类型卫星);
//如果要读取文件,则读取坐标
if(fileToBeRead!=null)
{
读取数据(fileToBeRead);
fileToBeRead=null;
}
//获取坐标列表
cooridnatesList=MainActivity.getList();
if(cooridnatesList!=null)
{
//从每个点添加一个标记
对于(int i=0;i尝试将所有引用GoogleMap的代码移动到onStart()或onResume()。映射片段中的映射只有在片段经过onCreateView()之后才会实例化。此外,您需要检查您的google地图是否为空,因为如果没有安装google play服务,或者地图因其他原因不可用,它将为空。您错过了最重要的一部分-logcat的堆栈跟踪。@Simon没有,他没有;它就在顶部。问题似乎是mapFragment.getMap()
正在返回null
;我不熟悉API,但我会检查它这样做的原因。@chrylis Doh。一大早没有咖啡。我怎么会错过呢?