I am still playing around with my calendar, I already nearly managed to integrate the https://github.com/SundeepK/CompactCalendarView into one of my fragments. There is just one error left, i did some research, others got the problem too for example with ArrayList<>. Example code: The IDE says: Note: C:…Uebersicht.java uses or overrides a deprecated API. Note: Recompile with -Xlint:deprecation for details. I