🟢 Basic Level

🔹 Module 1: Java Fundamentals – Variables, Control Flow, and OOP Basics

• Java syntax, structure, data types, variables

• Control statements (if, switch, loops)

• Methods, method overloading, parameters

• Classes and objects

• Access modifiers, static keyword

• Inheritance, encapsulation, abstraction, polymorphism

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🟡 Intermediate Level

🔹 Module 1: Java Classes, Objects, and Core OOP

• this, super, constructor chaining

• Object composition and association

• Static vs instance fields and methods

• equals(), hashCode(), and toString()

• Final keyword and immutability
   

🔹 Module 2: Design Patterns – Creational, Structural, Behavioral​

• Creational: Singleton, Factory, Builder, Prototype, Abstract Factory, Factory Method, Adapter

• Structural: Adapter, Bridge, Proxy, Composite, Decorator, Facade, Flyweight

• Behavioral: Strategy, Observer, Command, Template Method, Iterator

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🔵 Advanced Level

🔹 Module 1: Java Multithreading and Concurrency

• Threads, Runnable, Thread lifecycle

• Thread states, join(), sleep(), yield()

• Race conditions and thread safety

• Synchronization using synchronized

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🔹 Module 2: Thread Synchronization with ReentrantLock

• Locks vs synchronized blocks

• ReentrantLock for better for advanced/fine-tuned control

• Deadlocks and starvation
   

🔹 Module 3: Thread Pool and Executor Framework

• ExecutorService and Executors

• Fixed thread pools, cached thread pools, single-thread executors

• Callable vs Runnable

• Future and result management
   

🔹 Module 4: Advanced Structured Concurrency

• Problems with unstructured concurrency

• Structured concurrency principles

• Task scoping, cancellation, exception handling

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🟣 Modern Java (Java 14–21 Features)

🔹 Module 1: Virtual Threads and Project Loom

• Virtual Threads vs Platform Threads

• Benefits for I/O-heavy applications

• Migrating from traditional threading

• Scoped values (Java 20+)

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🔹 Module 2: Functional Programming & Streams

• Lambda expressions (syntax, scope, best practices)

• Method references and constructor references

• Functional interfaces (Function, Predicate, Supplier, etc.)

• Streams API:

  • Filtering, mapping, reducing

  • Collectors (toList(), joining(), groupingBy())

  • flatMap, peek, limit, skip, etc.

  • Parallel streams vs sequential streams

• Optional<T> usage patterns

• Collectors.teeing() and other advanced collectors

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🔹 Module 3: Collections & Generics Deep Dive

• List, Set, Map, Queue (implementations & use-cases)

• HashMap, LinkedHashMap, TreeMap, ConcurrentHashMap

• ArrayList vs LinkedList performance

• Stack vs Deque vs Queue

• Immutable collections (List.of(), Set.of())

• Iterable, Iterator, ListIterator

• Java Generics:

  • Generic classes and methods

  • Wildcards (?, ? extends, ? super)

  • Bounded type parameters

  • Type erasure

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🔹 Module 4: Java Language Enhancements (Java 14–21)

• Records (Immutable data carriers)

• Pattern Matching for instanceof

• Pattern Matching for switch (Java 17+)

• Switch Expressions (vs Traditional switch)

• Text Blocks (""" for multiline strings)

• Sealed Classes and Interfaces

• Scoped Values (Project Loom, Java 20+)

• Helpful NullPointerExceptions

• Preview features (how to enable and use them)

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🔴 Expert Level

🔹 Module 1: Exception Handling Mastery

• Checked vs Unchecked exceptions

• try-catch-finally, multi-catch

• try-with-resources and AutoCloseable

• Creating custom exceptions

• Exception chaining and logging

• Suppressed exceptions (in try-with-resources)

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🔹 Module 2: File I/O and NIO.2

• java.io vs java.nio

• Path, Files, FileVisitor

• Reading/writing files (line by line, buffered)

• WatchService API (monitor directory changes)

• FileChannel, ByteBuffer

• Memory-mapped files

• AsynchronousFileChannel

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🔹 Module 3: Java Networking & HTTP Client

• Sockets & ServerSockets (TCP/IP)

• DatagramSocket (UDP)

• Multithreaded server using ExecutorService

• Java 11+ HTTP Client API:

  • HttpRequest, HttpResponse

  • Async and synchronous calls

  • Web APIs (GET, POST with JSON)

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🔹 Module 4: Tooling, Modules, and Build Systems

• Reflection API: Class, Method, Field, dynamic access

• Annotations: Built-in annotations (@Override, @Deprecated, etc.), Custom annotations, Runtime retention and processing

• Java Platform Module System (JPMS)

  • module-info.java

  • Exports, requires, opens

• Javadoc generation and tags

• JShell (for REPL-based exploration)

• Maven & Gradle basics

  • Dependency management

  • Build lifecycle

  • Plugins

• Unit Testing with JUnit 5

• Mocking with Mockito​