In your activity’s onCreate(), do the processing within the if block: (you are getting the error because you may be asking for permissions with simultaneous processing in the onCreate()):
askForPermissions();
if(checkForPermission()){
//Do your processing here
}
The functions are:
void askForPermissions(){
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if(checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)!= PackageManager.PERMISSION_GRANTED){
requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.READ_EXTERNAL_STORAGE}, PERMISSION_REQUEST_CODE);
}
}
}
boolean checkForPermission(){
return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M;
}