This should help you:
Uri selectedUri = Uri.parse(Environment.getExternalStorageDirectory() + "/myFolder/");
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(selectedUri, "resource/folder");
if (intent.resolveActivityInfo(getPackageManager(), 0) != null)
{
startActivity(intent);
}
else
{
// if you reach this place, it means there is no any file
// explorer app installed on your device
}
Please, be sure that you have any file explorer app installed on your device.
EDIT: added a shantanu’s recommendation from the comment.
LIBRARIES:
You can also have a look at the following libraries https://android-arsenal.com/tag/35 if the current solution doesn’t help you.