Description
Core Java Interview Questions and Answers basic to Advanced, Real-time Scenario-Based and Coding Based
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Experience‑graded list of Core Java topics—from essential basics to deep advanced areas—tailored for candidates with 3–20 years of experience.
- Java Fundamentals: data types, operators, control flow, arrays, and the Java memory model.
- Object Oriented Design: classes, objects, inheritance, polymorphism, abstraction, encapsulation, and SOLID principles.
- Core APIs and Language Features: String handling, enums, annotations, var, records, and local-variable type inference.
- Exception Handling and I/O: checked vs unchecked exceptions, try-with-resources, NIO, file and stream APIs.
- Collections and Generics: List/Set/Map implementations, concurrency-safe collections, iterators, and generic type bounds.
- Concurrency and Multithreading: threads, executors, synchronization, locks, volatile, atomic classes, and thread pools.
- JVM Internals and Performance: class loading, bytecode, JIT, garbage collection algorithms, memory tuning and profiling.
- Advanced Java Concurrency: CompletableFuture, ForkJoinPool, reactive streams basics, and designing lock-free algorithms.
- Design Patterns and Architecture: creational/structural/behavioral patterns, microservices considerations, and modular design.
- Security and Best Practices: secure coding, input validation, classpath risks, and common Java vulnerabilities.
- Testing, Tooling and Build: unit/integration testing (JUnit, Mockito), CI/CD basics, Maven/Gradle, and static analysis.
- Modern Ecosystem & Integration
