java-primitives

Contains exercises for getting used to java syntax

Core Java Roadmap — Checklist

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Stage 1: Language Fundamentals

• Understand Java syntax and structure
• Learn data types and variable declaration
• Practice operators and expressions
• Implement conditionals (if, switch)
• Work with loops (for, while, do-while)
• Use basic input/output (Scanner, System.out)

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Stage 2: Object-Oriented Programming

• Create classes and objects
• Use constructors and method overloading
• Apply inheritance and method overriding
• Understand interfaces and abstract classes
• Practice encapsulation with access modifiers
• Implement polymorphism examples

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Stage 3: Core APIs & Utilities

• Manipulate Strings and StringBuilder
• Use wrapper classes (Integer, Double, etc.)
• Work with arrays and utility methods (Arrays.sort, etc.)
• Explore java.util tools (Math, Objects, etc.)

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Stage 4: Collections Framework

• Learn List, Set, Map, Queue interfaces
• Queue, Deque, Java Streams
• Use ArrayList, LinkedList, HashSet, TreeSet
• Work with HashMap, TreeMap
• Practice iterators and enhanced for-loop
• Understand Comparable vs Comparator

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Stage 5: Exception Handling

• Use try-catch-finally
• Differentiate checked vs unchecked exceptions
• Create custom exceptions
• Use try-with-resources

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Stage 6: Java I/O and File Handling

• Work with File, FileReader, FileWriter
• Use BufferedReader/BufferedWriter
• Understand byte vs character streams
• Try serialization basics

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Stage 7: Multithreading and Concurrency

• Extend Thread class and implement Runnable
• Understand thread lifecycle
• Use synchronized, locks
• Try wait(), notify(), notifyAll()
• Learn ExecutorService and thread pools

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Stage 8: Java 8+ Features

• Write lambda expressions
• Use functional interfaces
• Work with Stream API
• Try method references
• Handle nulls with Optional

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Stage 9: JVM Internals (Optional)

• Learn Java memory model
• Understand garbage collection basics
• Explore class loading mechanisms
• Research JIT compilation

🚀 Advanced Java Essentials

• Reflection and Annotations
• Lambda & Stream API mastery
• java.time Date and Time API
• Immutability and Records

💾 JDBC + JPA + Hibernate

• JDBC basics
• JPA (Java Persistence API)
• Hibernate ORM
• OneToMany, ManyToOne, etc.
• Lazy vs Eager loading
• JPQL / Criteria API
• Transactions & Caching

🌱 Spring Framework

Spring Core

• Dependency Injection
• Beans and Scopes

Spring Boot

• Auto-configuration
• REST APIs with Spring Boot
• Spring Data JPA (CRUD)
• Validation with @Valid

Spring MVC

• Controllers and Routing
• Exception handling with @ControllerAdvice
• Path params, query params, request body

🔐 Spring Security

• Auth & Authorization
• In-memory & DB users
• JWT authentication
• OAuth2 login (Google/GitHub)

🧪 Testing

• JUnit 5
• Spring Boot Test
• Mockito mocking

🌍 REST API Best Practices

• HTTP status codes
• DTOs and response wrappers
• Pagination, filtering, sorting
• Swagger / OpenAPI docs

⚙️ Tools

• Maven / Gradle
• Postman
• Lombok

🗃️ Database Design

• SQL basics (joins, indexes)
• PostgreSQL / MySQL
• Flyway / Liquibase

📦 Docker + Deployment

• Dockerize Spring Boot apps
• Docker Compose
• Heroku / Render / Railway deployment
• CI/CD basics

⭐ Optional Skills

• Spring Cloud (microservices)
• Redis (cache/sessions)
• RabbitMQ / Kafka (queues)
• Monitoring with Micrometer + Prometheus + Grafana