错误 locationManager.getLastKnownLocation

Question

我遵循有关半正弦公式的教程

这是我在 MainAcitvity 中的函数 lokasi()

 private void lokasi(){
    location = locationManager.getLastKnownLocation(provider);
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) !=
            PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this,
            Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }

    // permintaan update lokasi device dalam waktu 10 detik
    locationManager.requestLocationUpdates(provider, 10000, 1, this);

    if(location!=null){
        onLocationChanged(location);
        callListVolley(latitude, longitude);
    }else{
        Toast.makeText(getBaseContext(), "Lokasi device pengguna tidak ditemukan.\nMohon hidupkan GPS.",
                Toast.LENGTH_LONG).show();
        callListVolley(-6.894796, 110.638413);
    }
}

所以当我运行然后出现这个错误

FATAL EXCEPTION: main
                                                                         Process: com.example.invader.haversine, PID: 5913
                                                                         java.lang.IllegalArgumentException: invalid provider: null
                                                                             at android.location.LocationManager.checkProvider(LocationManager.java:1704)
                                                                             at android.location.LocationManager.getLastKnownLocation(LocationManager.java:1194)
                                                                             **at com.example.invader.haversine.MainActivity.lokasi(MainActivity.java:84)
                                                                             at com.example.invader.haversine.MainActivity.access[=12=]0(MainActivity.java:36)
                                                                             at com.example.invader.haversine.MainActivity.run(MainActivity.java:73)**

所以当我签入时 logcat 错误出现在功能开始时，但我不知道我应该怎么做

Answer 1

首先，您应该在请求位置之前检查权限。其次，您应该检查提供程序是否存在以及是否已启用。

if(locationManager.getAllProviders().contains(LocationManager.GPS_PROVIDER) && locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){ provider = LocationManager.GPS_PROVIDER; }

例如，如果您想使用 GPS_PROVIDER

错误 locationManager.getLastKnownLocation

Error locationManager.getLastKnownLocation

android

haversine