Top 85 Java Interview Questions & Answers

Java Interview Questions & Answers (85 Curated Q&A)

Ace your next Java interview with this updated 2025 guide — designed for software engineers from junior to senior level.

This guide includes 85 carefully selected Java interview questions with clear, detailed answers. Each question is explained with real-world examples, common pitfalls, and expert insights so you’ll walk into your interview with confidence.

✅ What You’ll Get

• 85+ interview questions with answers
• Real-world code snippets & explanations
• Tips from hiring managers & senior engineers
• Covers fundamentals to advanced topics
• Structured progression — from basics to JVM internals

📂 Topics Covered

Chapter 1 – Java Fundamentals

• Syntax, data types, control flow, methods

Chapter 2 – Object-Oriented Programming

• Classes, inheritance, polymorphism, abstraction

Chapter 3 – Core APIs

• Strings, Collections, Exception handling, I/O

Chapter 4 – Advanced Java

• Generics, Reflection, Lambda, Streams

Chapter 5 – Concurrency & Multithreading

• Threads, synchronization, concurrent collections

Chapter 6 – JVM & Performance

• Garbage collection, tuning, memory management