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40 Java Backend Interview Questions to Prepare for in 2026 | 25–30 LPA Salary Range
Preparing for a senior Java backend developer role in 2026? For positions offering compensation in the ₹25–30 LPA range, interviewers often look beyond Java syntax and basic Spring Boot concepts. They evaluate your understanding of concurrency, JVM internals, database consistency, distributed systems, application security, and system design.
The following questions cover important areas to practise for experienced Java backend interviews. Use them to assess your fundamentals and prepare for scenario-based discussions.
1. Core Java and Multithreading
1. How Does ConcurrentHashMap Ensure Thread Safety Internally?
Explain how ConcurrentHashMap supports concurrent reads and updates without locking the entire map. Discuss bucket-level synchronization, CAS operations, handling hash collisions, and how its implementation evolved from Java 7 to Java 8 and later versions.
2. What Is the Difference Between wait(), sleep(), and join()?
Explain the purpose of each method and how it affects thread execution.
wait()releases the monitor lock and waits for…
