i added in my MainActivity this code below, and i solve it. Thank a lot
ActivityCompat.requestPermissions(MainActivity.this,
new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
1);
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case 1: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
/*HERE PERMISSION IS ALLOWED.
*
* YOU SHOULD CODE HERE*/
} else {
Toast.makeText(MainActivity.this, "Permission deny to read your External storage", Toast.LENGTH_SHORT).show();
}
return;
}
// other 'case' lines to check for other
// permissions this app might request
}
}