I am not sure what you mean that OOP is intuitively harder to understand than functional programming. In fact, OOP was explicitly conceived as a more intuitive

I am not sure what you mean that OOP is intuitively harder to understand than functional programming. In fact, OOP was explicitly conceived as a more intuitive alternative to traditional languages, and most modern languages implement its core concepts in some way. Java is classic OOP, and is a good way to learn these concepts, so you may want to begin there. Of course, I agree with everyone that you shouldn't be worrying about these things. You can learn many of these things through experience, and the bonus is you can get stuff done at the same time.