The complete guide with code examples, evaluation rubrics, and follow-ups

Java Interview Questions

Whether you're preparing for a Java interview or building your hiring process, this guide covers everything from fundamentals to Spring Framework. Each question includes code examples, what great answers look like, and red flags to watch for.

30+ Questions

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What's Covered in This Guide

Java Fundamentals

10 questions

Object-Oriented Programming

5 questions

Collections Framework

5 questions

Concurrency & Multithreading

5 questions

Spring Framework

5 questions

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Java Fundamentals

10 questions

Object-Oriented Programming

5 questions

Collections Framework

5 questions

Concurrency & Multithreading

5 questions

Spring Framework

5 questions

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The complete guide with code examples, evaluation rubrics, and follow-ups

Java Interview Questions

What's Covered in This Guide

Java Fundamentals

What is the difference between JDK, JRE, and JVM?

Explain the difference between == and .equals() in Java.

What is the difference between String, StringBuilder, and StringBuffer?

What are access modifiers in Java and what are their scopes?

What is the difference between final, finally, and finalize?

Explain method overloading vs method overriding.

What is autoboxing and unboxing in Java?

What is the difference between checked and unchecked exceptions?

What is the purpose of the static keyword in Java?

What is the difference between an interface and an abstract class?

Object-Oriented Programming

Explain the four pillars of Object-Oriented Programming in Java.

What is the diamond problem and how does Java solve it?

What is the difference between shallow copy and deep copy?

What is an immutable class and how do you create one?

What is the difference between composition and inheritance?

Collections Framework

What is the difference between ArrayList and LinkedList?

How does HashMap work internally?

What is the difference between HashMap, LinkedHashMap, and TreeMap?

What is the difference between fail-fast and fail-safe iterators?

What is the difference between Comparable and Comparator?

Concurrency & Multithreading

What is the difference between a Thread and a Runnable?

What is the volatile keyword and when should you use it?

Explain synchronized and the different ways to use it.

What is a deadlock and how do you prevent it?

What is the ExecutorService and why should you use it?

Spring Framework

What is dependency injection and how does Spring implement it?

What is the difference between @Component, @Service, @Repository, and @Controller?

What are the different bean scopes in Spring?

Explain the @Transactional annotation and transaction propagation.

What is Spring Boot auto-configuration and how does it work?

Test Java skills with real coding challenges

Go Beyond Interview Questions