Nullpointerexception while running the project.

Hello,

I am currently working on an app to get a good overview of scheduled events. I dont have any errors in my project itself, but when I try to run my project locally an error occurs. 
I get a nullpointerexception but I have no idea where the error is coming from. I made a printscreen to hopefully clearify my problem and hope someone has the answer. 

Thanks in advance!