I´m new to android development and I´m trying to write a small, simple Application. This application should do nothing more than reading the text from 2 EditTexts and when
Your button is inside activity_main.xml, but you're inflating R.layout.headline_view:
activity_main.xml
R.layout.headline_view
this.inflatedView = inflater.inflate(R.layout.headline_view, container, false);