0

以下用于推导经度和纬度的代码给了我一个 NPE

初始声明：

double longitude, latitude;
Location location;
LocationManager manager;

代码：

final LocationListener locationListener = new LocationListener(){

                        @Override
                        public void onLocationChanged(Location arg0) {
                            // TODO Auto-generated method stub
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }

                        @Override
                        public void onProviderDisabled(String arg0) {
                            // TODO Auto-generated method stub

                        }

                        @Override
                        public void onProviderEnabled(String arg0) {
                            // TODO Auto-generated method stub

                        }

                        @Override
                        public void onStatusChanged(String arg0, int arg1,
                                Bundle arg2) {
                            // TODO Auto-generated method stub

                        }

                    };
                    manager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 2000, 10, locationListener);
                    location = manager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
                    longitude = location.getLongitude();
                    latitude = location.getLatitude();
                    Toast.makeText(getApplicationContext(), "lat and lon"+latitude+" "+longitude, Toast.LENGTH_LONG).show();

NPE发生在

longitude = location.getLongitude(); //Line 91

日志猫：

09-01 09:58:27.689: D/AndroidRuntime(3073): Shutting down VM
09-01 09:58:27.689: W/dalvikvm(3073): threadid=1: thread exiting with uncaught exception (group=0x40df98a8)
09-01 09:58:27.749: E/AndroidRuntime(3073): FATAL EXCEPTION: main
09-01 09:58:27.749: E/AndroidRuntime(3073): java.lang.NullPointerException
09-01 09:58:27.749: E/AndroidRuntime(3073):     at com.vaw.selfhelp.SmsActivity$2.onClick(SmsActivity.java:91)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at android.view.View.performClick(View.java:4091)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at android.view.View$PerformClick.run(View.java:17072)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at android.os.Handler.handleCallback(Handler.java:615)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at android.os.Handler.dispatchMessage(Handler.java:92)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at android.os.Looper.loop(Looper.java:153)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at android.app.ActivityThread.main(ActivityThread.java:4987)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at java.lang.reflect.Method.invokeNative(Native Method)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at java.lang.reflect.Method.invoke(Method.java:511)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
09-01 09:58:27.749: E/AndroidRuntime(3073):     at dalvik.system.NativeStart.main(Native Method)

使用以下权限：

<uses-permission android:name="android.permission.CALL_PHONE"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.SEND_SMS"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
4

1 回答 1

2

location您正在使用未初始化的变量。而是使用arg0变量

@Override
public void onLocationChanged(Location arg0) {
    // TODO Auto-generated method stub
    latitude = arg0.getLatitude();
    longitude = arg0.getLongitude();
}

或者你可以location先初始化你的变量：

@Override
public void onLocationChanged(Location arg0) {
    // TODO Auto-generated method stub
    location=arg0;
    latitude = location.getLatitude();
    longitude = location.getLongitude();
}
于 2013-09-01T04:29:17.123 回答