These examples are good for recursion, inheritance, and polymorphism problems.  (Though please note that polymorphism is not on Exam 2!)  The difficulty for these also isn't quite the same as what will be on the test; some are more complex and involved than what's on the test, while others may be a little simpler.

For recursion: https://codingbat.com/java/Recursion-1 and https://codingbat.com/java/Recursion-2
For some simple inheritance work: https://www.w3resource.com/java-exercises/index-inheritance.php
Simple Polymorphism: https://www.geeksforgeeks.org/output-java-program-set-25-polymorphism/#

As you work through these problems, let me know if you find them helpful!  (And, if you don't find them helpful, let me know, and we can figure something out!)