Android通过位置管理器获取经度和纬度

问题描述

我试图通过位置管理器获取用户位置，但位置始终返回空值。我还要求用户打开GPS。

这是我的代码：

  int permisioncheck = ContextCompat.checkSelfPermission（getActivity（），Manifest.permission.ACCESS_FINE_LOCATION）; 
 
 if（permisioncheck == 0）{
 
 lm =（LocationManager）getContext（）。getSystemService（Context.LOCATION_SERVICE）; 
 
列表< String> providers = lm.getProviders（true）; 
 
位置bestLocation = null; 
 
（String provider：providers）{
 Location location = lm.getLastKnownLocation（provider）; 
 if（location == null）{
 continue; （bestLocation == null || location.getAccuracy（））< bestLocation.getAccuracy（））{
 //找到最好的最后一个已知位置：％s ，l）; 
 bestLocation = location; 
} 
} 
 
 if（bestLocation == null）{
 System.out.println（is NULL！）; 
} 
} else {
 
 ActivityCompat.requestPermissions（getActivity（），new String [] {Manifest.permission.ACCESS_FINE_LOCATION}，1）; 
 
  

我希望有人能帮我找到错误，谢谢。

解决方案

错误是假设 getLastKnownLocation（）会返回一个 Location 。通常，它会返回 null 。使用 getLastKnownLocation（）作为可能的优化，但除此之外，您需要 requestLocationUpdates（），然后使用位置在 onLocationChanged（）方法中。

请参阅和以获取更多信息。

I'm trying to get the user location with location manager but the location always returns null. I also am asking to the user to turn on the gps.

This is my code:

   int permisioncheck = ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION);

    if(permisioncheck == 0){

        lm = (LocationManager)getContext().getSystemService(Context.LOCATION_SERVICE);

        List<String> providers = lm.getProviders(true);

        Location bestLocation = null;

        for (String provider : providers) {
            Location location = lm.getLastKnownLocation(provider);
            if (location == null) {
                continue;
            }

            if (bestLocation == null || location.getAccuracy() < bestLocation.getAccuracy()) {
                // Found best last known location: %s", l);
                bestLocation = location;
            }
        }

        if(bestLocation == null){
            System.out.println("is NULL!");
        }
    }else{

        ActivityCompat.requestPermissions(getActivity(), new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);
    }

I hope that someone could help me to find the error, thanks.

解决方案

The "error" is that you are assuming that getLastKnownLocation() will return a Location. Frequently, it will return null. Use getLastKnownLocation() as a possible optimization, but otherwise you need to requestLocationUpdates(), then use the location in the onLocationChanged() method.

See this sample project and the documentation for more.

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