One topic at a time: the rules I got wrong, then varied drills until they stick.
Exam: 50 questions · 120 min · pass = 68%
Every code drill has been compiled and run on JDK 21.
Each topic page has a one-screen rules summary, then drill blocks of original questions. The question order and option order shuffle on every reload, so you can't memorise positions. Then sit the timed mock at the bottom of the page. It draws a fresh random set from every block and gives no feedback until you submit, like the real exam. Your scores are saved in this browser.