I want to mention the user, as I showed in this picture, I don't understand how to do it, I had attempts I tried to do:
event.getChannel().send Message("@" + event.getMember().getNickname()).queue();
or
event.getChannel().send Message("@everyone").queue();

Discord mentions are done using IDs. A user mention is formatted as
<@{user_id}>. In your message, this would be done this way:However, you can also just use the existing method on members:
If you only have an id, you can also use
UserSnowflake