关于android：启用了GPS提供程序，但getLastKnownLocation(provider)返回null

GPS provider enabled but getLastKnownLocation(provider) returns null

我正在尝试为我的应用程序使用GPS提供程序。

该应用程序使用GPS位置提供程序查找设备的当前位置。

该应用程序工作正常。但是，虽然我的GPS_Provider已启用，但geLastKnownLocation()返回null。

MainActivity.java

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public class MainActivity extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

LocationManager locationManager;
String context = Context.LOCATION_SERVICE;
locationManager = (LocationManager)getSystemService(context);

String provider = LocationManager.GPS_PROVIDER;
Location location = locationManager.getLastKnownLocation(provider);

Log.v("BEFORE","Location is:" + location);
updateWithNewLocation(location);
Log.v("AFTER","LOCATION FOUND");
}

private void updateWithNewLocation(Location location){
String latLongString;
TextView myLocationText;
myLocationText = (TextView)findViewById(R.id.myLocationText);

if (location != null) {
double lat = location.getLatitude();
double lng = location.getLongitude();
latLongString ="Lat:" + lat +"
Long:" + lng;
}
else {
latLongString ="No location found";
}

myLocationText.setText("Your Current Position is:
" + latLongString);
}

}

的Manifest.xml

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