Is it possible to use the JDK for free to develop Android applications?

Question

Java

Hello.
I have just started learning Java, but I already have some misunderstandings related to using the JDK in commercial and non-commercial projects. Since from 04/16/2019 the license to use the JDK in commercial projects requires payment, I had a question: is it possible to use the JDK for free to develop Android applications? Will I need to buy a license if:
a) the application is free, it has no ads and purchases;
b) the application is free, but it has ads and / or purchases;
c) Is the app paid?
And one more question: will the use of the JDK for open source projects also be free?

Sorry for these possibly stupid questions, I just want to get this straight. Thank you.

Answer 1

Is Java now paid?

Answer 2

You don't need to buy any licenses.
Use the official OpenJDK or any third party build , preferably the bundled one from Android Studio.