在Android Studio中使用多个库构建项目

so basically I'm trying to make this tinder swipe application. Now I've imported two libraries, AndTinder and AndTinderDemo. Now when I run the project only my mainActivity.java in AndTinderDemo runs and not my main.java in the activity i personally created. What i want to do is put the code that's in the mainactivity.java of my AndtinderDemo and put it in my main.java of my activity i created and let it run that. I have no idea how to manipulate what my Android studio should run in a hierarchy. so basically I'm trying to make this tinder swi