Android 6.0+ dangerous permissions runtime request

runtimePermission.java

// if the device is running Android 6.0 (API level 23) 
// and the app's targetSdkVersion is 23 or higher, 

//the following system behavior applies when your app requests a dangerous permission:
// 1.
//If the app doesn't currently have any permissions in the permission group, 
//the system shows the permission request dialog to the user describing the permission group 
//that the app wants access to. The dialog doesn't describe the specific permission within 
//that group. For example, if an app requests the READ_CONTACTS permission, 
//the system dialog just says the app needs access to the device's contacts. 
//If the user grants approval, the system gives the app just the permission it requested.
// 2.
//If the app has already been granted another dangerous permission in the same permission group, 
//the system immediately grants the permission without any interaction with the user. 
//For example, if an app had previously requested and been granted the READ_CONTACTS permission, 
//and it then requests WRITE_CONTACTS, the system immediately grants that permission without 
//showing the permissions dialog to the user.

//refs
//https://developer.android.com/guide/topics/permissions/overview#permission-groups
//https://developer.android.com/reference/android/os/Build.VERSION_CODES

public static final int REQUEST_DANGEROUS_PERMISSIONS = 1001;

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
    requestDangerousPermissions();
}

private void requestDangerousPermissions() {
    List<String> perms = new ArrayList<>();
    if (ContextCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
      perms.add(Manifest.permission.ACCESS_FINE_LOCATION);
    }
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
      perms.add(Manifest.permission.CAMERA);
    }
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
      perms.add(Manifest.permission.WRITE_EXTERNAL_STORAGE);
    }
    if (perms.size() > 0) {
      ActivityCompat.requestPermissions(this,
          perms.toArray(new String[0]),
          REQUEST_DANGEROUS_PERMISSIONS);
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == REQUEST_DANGEROUS_PERMISSIONS) {
      if (requestCode == RESULT_CANCELED) {
        //finish();
      }
    }
}