There's probably newer AI powered tools but Tabula is the main library I know of https://github.com/tabulapdf/tabula-java

You can use a PDF parser tool to extract data from PDF tables. I'm building parsio.io - we use pre-trained AI-powered parsers to parse PDF tables: https://parsio.io/table-extraction/. Another example us Tabula (free)

there is also this option: https://docs.ropensci.org/tabulizer/

have not tried it, but this has been in my bookmarks a while: https://github.com/camelot-dev/excalibur