HashMap vs ConcurrentHashMap + Abstract Class vs Interface | Java Interview Prep
In this video, I explain two of the most commonly asked Java interview topics with clear comparisons, code examples, and interview-ready answers.
---- What you will learn ----
HashMap vs ConcurrentHashMap: thread safety, locking mechanism, null handling, fail-fast vs fail-safe iterators
Abstract Class vs Interface: purpose, methods, constructors, multiple inheritance, when to use each
---- Interview answers ----
HashMap: "Not thread-safe, used in single-threaded apps. ConcurrentHashMap locks only a part of the map, making it faster and safer for multi-threaded use."
Abstract Class vs Interface: "Use abstract class when classes share common code and state. Use interface when unrelated classes need the same contract."
---- Topics covered ----
Java Collections | Thread Safety | OOP | ConcurrentHashMap | Java 8 | Interview Questions
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