50+ Java Interview Questions for Programmers with 2 to 3 Years Experience
Basics:
- Solid understanding of OOPs concepts: Master core Object-Oriented Programming principles like Encapsulation,Inheritance, Polymorphism, and Abstraction. Be able to explain them clearly and use them effectively in your code.
- Java Collections Framework: Be comfortable with different types of collections (Lists, Sets, Maps) and their appropriate usage scenarios. Know their time and space complexity.
- Exception Handling: Understand different types of exceptions and how to handle them gracefully.
- Concurrency and Multithreading: Grasp thread fundamentals, synchronization mechanisms, and common concurrency issues like deadlock and livelock.
- JVM Internals: Knowledge of Garbage Collection, Class Loading, and Memory Management can show deeper understanding.
Beyond the Basics:
- Java 8+ Features: Familiarize yourself with lambda expressions, streams, functional programming concepts, and Optional types.
- Spring Framework: Learn the basics of Spring Boot or Spring MVC. Understanding dependency injection and bean configuration is crucial.
- Databases: Know SQL queries and be comfortable with relational databases like MySQL or PostgreSQL.
- Testing: Familiarity with unit testing frameworks like JUnit or Mockito is valuable. Data Structures and Algorithms: Revisit fundamental algorithms and data structures like sorting, searching, and graphs.