is it possible to automatically read messages from specific telegram groupchat(I am included in this groupchat) without adding bot to a group? Basically the goal is to process specific telegram messages using java, but without notifying ppl included in the group that bot is being used. Thank you.
A bot cannot possibly read messages without adding the bot to a group, as that would be a security and privacy issue. You can, however, make it slightly harder for people to notice by making sure not to have any commands listed with @botFather. See this answer.