It spans beginner through expert in one sitting. The early questions cover things every Java user meets — == vs .equals, Integer autoboxing, overflow. The later ones go into overload resolution, generics and collections, exceptions, concurrency and Stream laziness. Your score places you in one of four tiers, and the tier names are deliberately the ones job postings use.

No. Every question is written against core language behaviour that has been stable across modern Java versions — object identity, the collections framework, the exception hierarchy and basic concurrency primitives. Nothing here depends on a version-specific API.

It samples the same kind of read-and-predict reasoning most employer screens open with, in the same short-snippet format, which is why it works as preparation. It is not a copy of any specific employer test, and a good score here is not a certificate. What it does tell you is which of the four areas you would lose marks in, which is the useful thing to know before a technical interview.

About nine minutes. There is no timer on individual questions — the test measures whether you know what the code does, not how fast you can click. You can think about a question for as long as you like.