collections - sergeyzolotukhin/learn-java-gradle GitHub Wiki

🔹 Java Collections & Performance What is the internal structure of HashMap? How do you improve performance in large-scale Java apps? What is LinkedHashMap? How does it maintain order? How does ConcurrentHashMap avoid locking the whole map? Difference between fail-fast and fail-safe iterators?

🔹 Collections and Concurrency How does HashMap grow internally after Java 8? Why is ConcurrentHashMap faster than Hashtable? When does CopyOnWriteArrayList work well and when does it fail? Why is the size operation slow in ConcurrentHashMap? How does WeakHashMap remove keys automatically?

• What makes immutable objects advantageous as keys in HashMaps? https://medium.com/@abhishek.talakeriv/java-top-interview-questions-on-immutability-concept-70b2fce37f5e Using mutable objects as keys in a HashMap is highly dangerous