The German Java magazine JavaSPEKTRUM has published another article of mine in its second to last issue 2/2020. The article is titled “Du kommst hier nicht rein! – Locking in Java” (“You Can’t Come in Here!—Locking in Java”). It shows common pitfalls when dealing with multiple threads, even arising in situations where they are not expected, and shows several tools of modern Java APIs that help solving them. The article covers the nature of synchronization, the differences between intrinsic and explicit locking as well as atomic data types and fully synchronized data structures.