[libGDX] Can't localize assets folder with files

Hello,

I have problem with assets folder in my project.
I have line with localization of badlogic.jpg:

javaimg = new Texture("badlogic.jpg");

If I have this jpg file in ‘assets’ folder (in core), that java doesn’t see this file. I have to put this file in main folder of my project.
I have seen a lot of tutorials where people had this file in ‘assets’ folder and they use this kind of localization “badlogic.jpg”.
Where did I make a mistake?