you can refer to this video
https://www.youtube.com/watch?v=uFbwW4ERUN0
or check Prabeesh RK android MySQL playlist in youtube to learn more..
only difference will be instead of creating a new database you will already have one.
just ensure whatever tables you create has the table_prefix that matches your $table_prefix in wp-config.php file
Hope this helps
Take care and Happy coding
solved how do I create android app using wordpress database? [closed]