How to fill ArrayList with paths to files assets?

public void resetQuiz() {
 AssetManager assets = getActivity().getAssets();
fileNameList.clear();

 // Use AssetManager to retrieve the image file names
 try {
 for(String region:regionSet){
 String[] paths = assets.list(region);
 for(String path:regionSet){
 fileNameList.add(path.replace(".png", ""));
}
}
}
 catch(IOException ex) {
 Log.e(TAG, "Error loading image file names", ex);
}



 correctAnswers = 0;
 totalGuesses = 0;

quizCountriesList.clear();

 int flagCounter = 1;
 int numberOfFlags = fileNameList.size();

 // Add FLAGS_IN_QUIZ random file quizCountriesList
 while (flagCounter <= FLAGS_IN_QUIZ) {
 int randomIndex = random.nextInt(numberOfFlags);

 // Get random file name
 String filename = fileNameList.get(randomIndex);

 //If the region is enabled but has not yet been selected
 if (!quizCountriesList.contains(filename)) {
quizCountriesList.add(filename);

}
flagCounter++;
}

 loadNextFlag(); //Start the quiz by loading the first flag
 }