collections
4 articles
Java 8 Stream API Interview Questions, With the Output to Prove It
Java 8 stream interview questions answered with output from JDK 8, 21 and 25, including a sorted() that did no work and a parallel reduce wrong every time.
JavaJava Stream API Examples, and Four Ways They Surprise You
Complete stream examples with real output — grouping, flattening, collecting to a map — plus four behaviours that cause bugs not looking like stream bugs.
JavaHashSet vs HashMap: One Is Built Out of the Other
The difference is not two designs but one — javap shows a HashSet holding a HashMap. Every behaviour, and every failure mode, follows from that.
JavaArrayList vs LinkedList: The Numbers Behind the Table
Everyone knows the complexity table. Here is what each operation actually costs when you time it — including the one result that contradicts the folklore.
Java