Android Custom modification

I am working on a project for Android Platform and it’s not a game but a project that includes AR and need some management that i think should be done in Android like the need for another activity, fragment and other functionalities which i want to find a way to include them in the project for a better experience.
My question: is there a way to add Android classes (activity, fragment, library…) to the project? if yes, how to call them from ue4?