Smack4.1 on Android:connection closed with error

In this days, I am Using Smack 4.1 to develop an IM app on Android.

But, unfortunately,I have met some problems.I get a list of rooms that I have been joined,when I click one item of the list, i get the jid of this room and start aone chatActivity.
but when i am tring to use the method:muc.join(),Eclipse give me some warnings:

I am finding the solution,and i find Flow says, “Considering use XEP-0203”,what is means? Should i fix the source code? OR, there are some

other keys to my question?