Since Floating Action Buttons (FAB) appeared in Conversations joining into a group chat (MUC) it's not as intuitive as creating a new group at present.
The current way to create a new group chat is via FAB. Otherwise, to join into existing rooms is via menu (AdapterView.OnItemClickListener).
Following this flow, I doubt the main action is to create a new group and not to join
join an one. So for that reason I think that the FAB should be join into a group in any case.
But to continue to consistency and standards, I feel both options must be accessed on the same way.
My approach to the solution is to show two FABs, one for joining and another one for creating a group chat.
Something like this:

Another solution could be to press the FAB and collapse another two FABs: One to join a MUC an another to create a MUC. I give the Nextcloud Android app as an example:

Why in the world was this issue closed?
@STPKITT It's not closed. What do you mean?
By the way PRs welcome for the collapse / expand solution as shown in the screenshot @esu23 posted. There is no standard library for this so it is a bit of a pain to create this with all the animations and stuff. The prexising libraries (that I were able to find) don鈥檛 use the FAB from the standard library though. So a nice PR with nice animations that uses the standard FABs will very likely get merged.
How about, leaving the existing flow as is. And showing the join group chat dialog on long pressing the existing unmodified FAB? Because i dont see any real issue in existing flow where clicking the fab shows an activity to either choose from already added/bookmarked contacts/MUCs or create new(through this activity's fab). Just that the join existing MUC option hidden under menu needs to be streamlined. This would require minimal changes.
@iNPUTmice
can you check my pull request for this . #3236
Good job! But basically the join group chat (MUC) option has disappear (now it is only possible to join via invitation or by clicking in a xmpp URI previously shared).
I am not against this idea but the following feature is now missing: create a muc with a custom URI (which was possible before using the join MUC instead of creating a MUC).
Maybe it is a good idea to allow the user to custom the URI when the MUC is created.
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Another solution could be to press the FAB and collapse another two FABs: One to join a MUC an another to create a MUC. I give the Nextcloud Android app as an example: