Java Developer
From Java fundamentals through Spring Boot, JPA, microservices, Kafka, and cloud deployment. Java is the dominant language at banks, fintech, and large enterprises — Accenture, Deloitte, Stripe, and JPMorgan.
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☐ Core Java · Required · 12 hrs
Data types, OOP (inheritance, polymorphism, interfaces), exception handling, I/O, Generics, Enums. The language you will write every day.
☐ Git & Build Tools · Required · 3 hrs
Git version control, Maven or Gradle for dependency management and builds. Every Java project uses one of these.
- Git and Version Control for Data Projects (Data Engineering): https://chaduvuko.com/learn/data-engineering/git-for-data
☐ Collections & Streams · Required · 6 hrs
ArrayList, HashMap, LinkedList, TreeMap, Stream API, lambda expressions, Optional. The Java standard library is huge — know the important parts.
☐ Concurrency · Required · 6 hrs
Threads, ExecutorService, CompletableFuture, synchronized, volatile, concurrent collections. Critical for high-throughput backend services.
☐ SQL & JPA/Hibernate · Required · 6 hrs
PostgreSQL / MySQL basics, JPA entities, JPQL, transactions, N+1 problem. Java persistence is a career in itself.
- Your First Query — SELECT & FROM (SQL): https://chaduvuko.com/learn/sql/select-from
- Introduction to Joins (SQL): https://chaduvuko.com/learn/sql/joins-intro
- Grouping Data — GROUP BY (SQL): https://chaduvuko.com/learn/sql/group-by
- Subqueries — Queries Inside Queries (SQL): https://chaduvuko.com/learn/sql/subqueries
☐ Spring Boot · Required · 15 hrs
IoC, DI, REST controllers, Spring Data JPA, Spring Security, configuration, actuators. Spring Boot is the default Java backend framework.
☐ Testing (JUnit 5 + Mockito) · Required · 5 hrs
Unit tests, mocking with Mockito, Spring integration tests, TestContainers. Tested code ships faster.
☐ Docker & CI/CD · Required · 4 hrs
Containerise Spring Boot apps, multi-stage Docker builds, GitHub Actions pipeline. Modern Java services run in containers.
☐ DSA & Algorithms · Required · 25 hrs
LeetCode Medium problems in Java. Every $130K+ offer has a DSA round — no shortcuts.
- Complexity — The Scoreboard for Code (Data Structures & Algorithms): https://chaduvuko.com/learn/dsa/complexity
- Arrays (Data Structures & Algorithms): https://chaduvuko.com/learn/dsa/arrays
- Hashing (Data Structures & Algorithms): https://chaduvuko.com/learn/dsa/hashing
- Dynamic Programming (Data Structures & Algorithms): https://chaduvuko.com/learn/dsa/dynamic-programming
☐ Kafka · Recommended · 6 hrs
Producers, consumers, consumer groups, partitioning, Spring Kafka. Async messaging at fintech scale.
- What is Apache Kafka? (Apache Kafka): https://chaduvuko.com/learn/apache-kafka/what-is-apache-kafka
- Events, Topics, and Partitions (Apache Kafka): https://chaduvuko.com/learn/apache-kafka/events-topics-partitions
- Consumer Groups and Offsets (Apache Kafka): https://chaduvuko.com/learn/apache-kafka/consumer-groups-offsets
- Delivery Semantics: At-Most, At-Least, Exactly-Once (Apache Kafka): https://chaduvuko.com/learn/apache-kafka/delivery-semantics
☐ Microservices · Required · 8 hrs
Service decomposition, Feign clients, API gateway, distributed tracing, circuit breakers (Resilience4j). How large systems are structured.
☐ Cloud Deploy (AWS / Azure) · Required · 6 hrs
ECS/EKS, App Service, RDS, managed queues. Enterprise Java runs on cloud.
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