NullPointerException异常 - 位置 - getLatitude()方法 [英] NullPointerException - Location - getLatitude() method
问题描述
我在这一行接收一个空指针异常:
双纬度= location.getLatitude();
有什么我需要做初始化我的位置变量?我究竟做错了什么?
下面是我的源$ C $ C:
地点的位置; 如果(isGpsEnabled){
位置= locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
}
其他{
位置= locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
} Log.i(TAG,供应商是:+供应商);
Log.i(TAG,位置为:+位置);
//在活动开始时缩放到当前位置
双纬度= location.getLatitude();
双经度= location.getLongitude();
下面是logcat的输出我收到:
九月六日至17日:22:40.797:E / AndroidRuntime(12436):致命异常:主要
九月六日至17日:22:40.797:E / AndroidRuntime(12436):了java.lang.RuntimeException:无法启动活动ComponentInfo {com.android.gpstracker / com.polaris.epicriders.Rides.RideTracking}:显示java.lang.NullPointerException
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.ActivityThread.access $ 600(ActivityThread.java:141)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1234)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.os.Handler.dispatchMessage(Handler.java:99)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.os.Looper.loop(Looper.java:137)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.ActivityThread.main(ActivityThread.java:5041)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在java.lang.reflect.Method.invokeNative(本机方法)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在java.lang.reflect.Method.invoke(Method.java:511)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:793)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在dalvik.system.NativeStart.main(本机方法)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):致:显示java.lang.NullPointerException
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在com.polaris.epicriders.Rides.RideTracking.onCreate(RideTracking.java:273)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.Activity.performCreate(Activity.java:5104)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
九月六日至17日:22:40.797:E / AndroidRuntime(12436):... 11个
getLastKnownLocation
如果任何地点已经获得返回null
从<一个href=\"http://developer.android.com/reference/android/location/LocationManager.html#getLastKnownLocation%28java.lang.String%29\"相对=nofollow> DOC
返回一个位置指示从最后已知位置的数据
从给定的提供者获得弄不好
这可以在不启动供应商来完成。注意,这
位置可以是外的日期,例如,如果该设备被打开
关闭并移动到另一个位置。
如果供应商目前已禁用,则返回null。
块引用>I'm receiving a null pointer exception on this line:
double latitude = location.getLatitude();
Is there anything I need to be doing to initialize my Location variable? What am I doing wrong?
Here is my source code:
Location location; if (isGpsEnabled) { location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER); } else { location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER); } Log.i(TAG, "Provider is: "+provider); Log.i(TAG, "Location is: "+location); //Zooms into the current location when the activity is started double latitude = location.getLatitude(); double longitude = location.getLongitude();
Here is the logcat output I'm receiving:
06-17 09:22:40.797: E/AndroidRuntime(12436): FATAL EXCEPTION: main 06-17 09:22:40.797: E/AndroidRuntime(12436): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.gpstracker/com.polaris.epicriders.Rides.RideTracking}: java.lang.NullPointerException 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.ActivityThread.access$600(ActivityThread.java:141) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.os.Handler.dispatchMessage(Handler.java:99) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.os.Looper.loop(Looper.java:137) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.ActivityThread.main(ActivityThread.java:5041) 06-17 09:22:40.797: E/AndroidRuntime(12436): at java.lang.reflect.Method.invokeNative(Native Method) 06-17 09:22:40.797: E/AndroidRuntime(12436): at java.lang.reflect.Method.invoke(Method.java:511) 06-17 09:22:40.797: E/AndroidRuntime(12436): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 06-17 09:22:40.797: E/AndroidRuntime(12436): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 06-17 09:22:40.797: E/AndroidRuntime(12436): at dalvik.system.NativeStart.main(Native Method) 06-17 09:22:40.797: E/AndroidRuntime(12436): Caused by: java.lang.NullPointerException 06-17 09:22:40.797: E/AndroidRuntime(12436): at com.polaris.epicriders.Rides.RideTracking.onCreate(RideTracking.java:273) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.Activity.performCreate(Activity.java:5104) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 06-17 09:22:40.797: E/AndroidRuntime(12436): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 06-17 09:22:40.797: E/AndroidRuntime(12436): ... 11 more
解决方案
getLastKnownLocation
returns null if any Location has been acquiredfrom the doc
Returns a Location indicating the data from the last known location fix obtained from the given provider.
This can be done without starting the provider. Note that this location could be out-of-date, for example if the device was turned off and moved to another location.
If the provider is currently disabled, null is returned.
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