Java
A statically typed, object-oriented language powering enterprise backends, Android development, and large-scale distributed systems.
Java remains the dominant language for enterprise software, financial services, and Android development despite being over 25 years old. Its strong typing, mature ecosystem (Spring Boot, Hibernate), and performance characteristics make it the default choice at banks, insurance companies, large retailers, and any organization with significant enterprise software infrastructure.
Typical time to job-readiness: ~5 months.
Learning Java
Beginner
Learn Java syntax, OOP fundamentals (classes, inheritance, interfaces, generics), and the Collections framework. Set up a Maven or Gradle project.
Intermediate
Spring Boot for REST APIs, JPA/Hibernate for database access, and unit testing with JUnit and Mockito. Build and deploy a working API end-to-end.
Advanced
JVM internals (GC tuning, memory model), concurrent programming (CompletableFuture, virtual threads in Java 21+), and enterprise architecture patterns. Assessed through coding challenges and system design.
Key concepts
- Object-oriented programming: classes, interfaces, inheritance, and polymorphism
- JVM and garbage collection — Java manages memory automatically
- Generics and the Collections framework (List, Map, Set, Queue)
- Exceptions: checked vs unchecked and how to handle them
- Java 8+ features: Stream API, Optional, lambdas, and method references
- Concurrency: threads, synchronized, and CompletableFuture
Common interview topics
- Explain the difference between an interface and an abstract class in Java
- How does Java's garbage collection work
- What is the difference between HashMap and HashTable
- Explain the SOLID principles with examples
- How does Java handle concurrency and what is the synchronized keyword
- What are Java generics and why are they useful