How to convert docx (and some other text formats) to pdf in Android Studio Java?

Question

Java

I am writing a reader

He already knows how to:
-Open and view PDF files

Must learn to:
-Open and view dosx, rtf, epub, txt (or convert them to pdf and read pdf)

How can I implement the conversion or direct reading of such files (without using paid tools )?
Somewhere I saw a proposal to convert first to html, then to pdf (or something like that, but I didn’t find how to do it). Any but working option is needed

Answer 1

It is better not to convert, but to read directly.
As for the implementation, google "java how to read ..." and substitute the desired extension. There will be an answer.

Answer 2

From the context of the question, you might think that you are looking for a universal way for all formats.
If so, then there is no such way.
You need to study the description of the format you are interested in, and write an implementation for it. (with txt it's easiest here)
Or, google ready-made libraries, as you have already been advised.