How to fetch files and folders from my google drive to show these in my app?

How to fetch files and folders from my google drive to show these in my app?

Here is my code:
private void listfiles(Drive s )throws IOException
{
Toast.makeText(getApplicationContext(), "Inside listfiles now",
Toast.LENGTH_LONG).show();
List<File> result = new ArrayList<File>();
Files.List request = s.files().list();
Toast.makeText(getApplicationContext(), "list extracted",
Toast.LENGTH_LONG).show();
do {
try {
Toast.makeText(getApplicationContext(), "executing",
Toast.LENGTH_LONG).show();
FileList files = request.execute();
Toast.makeText(getApplicationContext(), "Executed",
Toast.LENGTH_LONG).show();
result.addAll(files.getItems());
request.setPageToken(files.getNextPageToken());
} catch (IOException e) {
Toast.makeText(getApplicationContext(), "Inside catch",
Toast.LENGTH_LONG).show();
System.out.println("An error occurred: " + e);
request.setPageToken(null);
}
} while (request.getPageToken() != null &&
request.getPageToken().length() > 0);
}
Please tell me how to do this. I really need it, I have been trying for a
long time.