Java with OpenSource

01

Introduction to Linux

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• Linux FundamentalsUnderstanding the Linux OS, file system hierarchy, terminal basics, and why Linux is the industry standard for development
• Essential CommandsNavigating directories, file operations (cp, mv, rm), permissions (chmod, chown), piping, redirection, and shell scripting basics
• Development Environment SetupInstalling JDK on Linux, setting PATH and JAVA_HOME, compiling and running Java programs from the terminal
• Git & Version Controlinit, add, commit, push, pull, branching, merging — collaborating on projects using Git and GitHub

02

Java Fundamentals & Language Basics

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• Java FundamentalsJDK, JRE, JVM overview, writing your first Java program, data types, variables, type casting, and literals
• Operators & AssignmentsArithmetic, relational, logical, bitwise, ternary, and assignment operators — precedence rules and evaluation order
• Flow Controlif-else, switch, for, while, do-while, break, continue, and nested loops — controlling program execution flow
• Declarations & Access ModifiersClass declarations, variable scopes, public, private, protected, default — understanding access levels and encapsulation

03

Object-Oriented Programming

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• OOP PrinciplesClasses, objects, inheritance, polymorphism, abstraction, encapsulation — the four pillars of object-oriented Java
• Interfaces & Abstract ClassesDefining contracts with interfaces, abstract methods, default methods, multiple inheritance, and real-world design patterns
• Inner ClassesMember inner classes, static nested classes, local inner classes, anonymous inner classes — when and why to use them
• PackagesOrganizing code with packages, import statements, access control across packages, and building modular Java applications

04

Exception Handling & Multi-Threading

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• Exception HandlingTry-catch-finally, checked vs unchecked exceptions, throw & throws, custom exceptions, and writing robust error-handling code
• Multi-ThreadingThread class, Runnable interface, thread lifecycle, synchronization, inter-thread communication, deadlocks, and concurrent programming

05

File I/O, Serialization & Collections

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• File I/OFileReader, FileWriter, BufferedReader, BufferedWriter, byte streams, character streams — reading and writing files in Java
• SerializationObjectInputStream, ObjectOutputStream, Serializable interface, transient keyword, custom serialization, and data persistence
• Collections FrameworkList, Set, Map, Queue — ArrayList, HashMap, HashSet, LinkedList, TreeMap, iterators, and choosing the right data structure
• GenericsGeneric classes, methods, bounded types, wildcards, type erasure — writing type-safe, reusable Java code

06

JVM Internals & Garbage Collection

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• JVM ArchitectureClassLoader, bytecode, JIT compilation, runtime data areas (heap, stack, method area), and how Java programs execute
• Garbage CollectionGC roots, mark-and-sweep, generational GC, G1 collector, memory leaks, finalize() — understanding automatic memory management
• Performance & DebuggingJVM flags, profiling tools, heap dumps, thread dumps, and diagnosing real-world performance issues

07

Open Source Projects — JSQLParser & Elasticsearch

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• JSQLParser — SQL Parsing in JavaUnderstanding the JSQLParser codebase, parsing SQL statements, AST traversal, and contributing to a widely-used SQL parsing library ↗ GitHub
• Elasticsearch — Distributed Search EngineExploring the Elasticsearch Java codebase, understanding distributed systems, indexing, querying, and contributing to one of the most popular open-source search engines ↗ GitHub
• Reading & Navigating Large CodebasesStrategies for understanding project structure, build systems (Maven/Gradle), running tests, and finding entry points in production-scale Java projects
• Contributing & Building Your PortfolioFinding good first issues, writing meaningful PRs, engaging with maintainers, documenting your contributions, and showcasing your open-source work