> is it possible to import CSV files without using POI
Then why didn't you ask that in your original question?
Your original question asked about importing external files like Excel. Well Excel has a proprietary format, which is why it was suggested you use POI.
Now that you've clarified the question by stating you want to "import" CSV files, you need to define what you mean by "import". A CSV file is just a text file you you can read it like any other file.
If you mean you want to "parse" a CSV file then search the forum as this question has been asked and answered several time.
Learn to search the forum before posting a question and learn to ask a clear question so we don't have to guess what you want.