I would like to download websites filled with tables and then convert then into something like an arraylist.
Is this possible with a parser? If so, can you please provide me some parsers that can be able to do that such as libraries.
Don't try to code this yourself. It's very hard to get right and it's a mess. There are a number of open-source HTML parser libraries in Java. See here for a reasonably good list of them. Start with one of those and then post a follow-up question if you get stuck on something.