強制的な権限チェックと静止場所= null

Question

私のコードで許可チェックの強制的な必要性を理解できません。

さらに、それを行った後でも、場所はnullです。

これは私のonCreateメソッドのコードです： 助けてください！

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    textView = (TextView) findViewById(R.id.textView); 

    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
    provider = locationManager.getBestProvider(new Criteria(), false); 

    if(provider.equals(null)){ 
     Log.i("provdier","prob"); 
    } 

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) { 
     // TODO: Consider calling 
     // ActivityCompat#requestPermissions 
     // here to request the missing permissions, and then overriding 
     // public void onRequestPermissionsResult(int requestCode, String[] permissions, 
     //           int[] grantResults) 
     // to handle the case where the user grants the permission. See the documentation 
     // for ActivityCompat#requestPermissions for more details. 
     return; 
    } 


    Location location = locationManager.getLastKnownLocation(provider); 

    if (location != null) { 
     Log.i("location info", "achieved"); 
     textView.setText("Achieved"); 
    } else { 
     Log.i("location info", "failed"); 
     textView.setText("Failed"); 
    } 
} 

Answer 1

これを試してください。

private Location getLastKnownLocation() { 

     LocationManager mLocationManager = (LocationManager) getApplicationContext().getSystemService(LOCATION_SERVICE); 
     List<String> providers = mLocationManager.getProviders(true); 
     Location bestLocation = null; 

     for (String provider : providers) { 

      if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) { 
       // TODO: Consider calling 
       // ActivityCompat#requestPermissions 
       // here to request the missing permissions, and then overriding 
       // public void onRequestPermissionsResult(int requestCode, String[] permissions, 
       //           int[] grantResults) 
       // to handle the case where the user grants the permission. See the documentation 
       // for ActivityCompat#requestPermissions for more details. 
       return TODO; 
      } 
      Location l = mLocationManager.getLastKnownLocation(provider); 
      if (l == null) { 
       continue; 
      } 
      if (bestLocation == null || l.getAccuracy() < bestLocation.getAccuracy()) { 
       // Found best last known location: %s", l); 
       bestLocation = l; 
      } 
     } 
     return bestLocation; 


    } 

Answer 2

私は同じ問題を抱えていましたが、developer.android.comが救助に来ました。

ただ、これらの2つのリンクを訪問し、問題が解決されます：参照用にまだ

1. Last Known location

2. Requesting Permissions

を。私のコード：その義務は、このコードでパーミッションチェックを追加しながら

public class MainActivity extends AppCompatActivity implements GoogleApiClient.ConnectionCallbacks, OnConnectionFailedListener { 

GoogleApiClient mGoogleApiClient; 
Location mLastLocation; 
TextView mLatitudeText, mLongitudeText; 
final int MY_PERMISSIONS_REQUEST_MAPS = 1; 

protected void onStart() { 
    mGoogleApiClient.connect(); 
    super.onStart(); 
} 

protected void onStop() { 
    mGoogleApiClient.disconnect(); 
    super.onStop(); 
} 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    mLatitudeText = (TextView) findViewById(R.id.textView); 
    mLongitudeText = (TextView) findViewById(R.id.textView2); 

    if (mGoogleApiClient == null) { 
     mGoogleApiClient = new GoogleApiClient.Builder(this) 
       .addConnectionCallbacks(this) 
       .addOnConnectionFailedListener(this) 
       .addApi(LocationServices.API) 
       .build(); 
    } 
    Log.i("permit Fine", ""+ ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)); 
    Log.i("permit coarse", ""+ContextCompat.checkSelfPermission(this,Manifest.permission.ACCESS_COARSE_LOCATION)); 
} 

@Override 
public void onConnected(@Nullable Bundle bundle) { 
    if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) { 
     // TODO: Consider calling 
     // ActivityCompat#requestPermissions 
     // here to request the missing permissions, and then overriding 
     // public void onRequestPermissionsResult(int requestCode, String[] permissions, 
     //           int[] grantResults) 
     // to handle the case where the user grants the permission. See the documentation 
     // for ActivityCompat#requestPermissions for more details. 
     if (ActivityCompat.shouldShowRequestPermissionRationale(this, 
       Manifest.permission.READ_CONTACTS)) { 

      // Show an explanation to the user *asynchronously* -- don't block 
      // this thread waiting for the user's response! After the user 
      // sees the explanation, try again to request the permission. 
      Log.i("in","Explaination"); 

     } else { 

      // No explanation needed, we can request the permission. 

      ActivityCompat.requestPermissions(this, 
        new String[]{Manifest.permission.ACCESS_FINE_LOCATION,Manifest.permission.ACCESS_COARSE_LOCATION}, 
        MY_PERMISSIONS_REQUEST_MAPS); 
      Log.i("in","Else"); 

      // MY_PERMISSIONS_REQUEST_READ_CONTACTS is an 
      // app-defined int constant. The callback method gets the 
      // result of the request. 
     } 
     return; 
    } 
    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
      mGoogleApiClient); 
    if (mLastLocation != null) { 
     mLatitudeText.setText(String.valueOf(mLastLocation.getLatitude())); 
     mLongitudeText.setText(String.valueOf(mLastLocation.getLongitude())); 
    } 
} 

@Override 
public void onRequestPermissionsResult(int requestCode, 
             String permissions[], int[] grantResults) { 
    switch (requestCode) { 
     case MY_PERMISSIONS_REQUEST_MAPS: { 
      // If request is cancelled, the result arrays are empty. 
      if (grantResults.length > 0 
        && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 

       // permission was granted, yay! Do the 
       // contacts-related task you need to do. 
       Log.i("permit Fine", ""+ ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)); 
       Log.i("permit coarse", ""+ContextCompat.checkSelfPermission(this,Manifest.permission.ACCESS_COARSE_LOCATION)); 

      } else { 

       // permission denied, boo! Disable the 
       // functionality that depends on this permission. 
      } 
      return; 
     } 

     // other 'case' lines to check for other 
     // permissions this app might request 
    } 
} 

@Override 
public void onConnectionSuspended(int i) { 

} 

@Override 
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) { 

} 

}