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• Apache-2.0 licensed
• ⚠ Slowing — last commit 10mo ago
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• ⚠ No CI workflows detected
• ⚠ No test directory detected
• ⚠ Scorecard: default branch unprotected (0/10)

_{Computed from maintenance signals — commit recency, contributor breadth, bus factor, license, CI, tests, cross-checked against OpenSSF Scorecard}

A comprehensive Java learning course repository containing 75 structured lessons with 150+ practical exercises, covering Java fundamentals and Object-Oriented Programming (OOP) from first principles. Organized in 10 progressive sections (basic/c00 through c10) with paired theory files and exercise files, each teaching concrete concepts like data types, operators, strings, loops, functions, classes, inheritance, polymorphism, and exception handling. Flat course structure: basic/ directory contains 11 sequential folders (c00_helloworld through c10_extras), each with 1–2 Java files. Most sections have a Theory.java file (e.g., basic/c03_strings/Strings.java) and a paired Exercises.java file (e.g., basic/c03_strings/StringsExercises.java). OOP section (c08_oop) includes model classes like Person.java and a separate test folder (c08_test_oop) for integration examples.

Absolute beginners and junior developers learning Java for the first time, who need a structured curriculum with worked examples and progressive exercises. Instructors and content creators can fork this to localize or extend the course with additional languages or topics.

Active and well-maintained educational content project. Single maintainer (mouredev) with 75 video lessons published on YouTube and organized exercise sets. No traditional CI/CD, test suite, or releases tracked — this is an educational repository, not a library or framework, so traditional maturity metrics don't apply. High star count indicates strong community adoption for learning purposes.

Low technical risk for learners. Single maintainer means sustainability depends on mouredev's commitment. No automated tests or CI pipeline, so code examples are validated by manual review and learner feedback only. No version compatibility matrix tracked (targets JDK 21+ per README badge). For production use, this is curriculum not framework — not a risk factor.

No recent commit data provided in the repository metadata. This is a complete, published curriculum; activity likely consists of occasional corrections, clarifications in response to learner issues, or supplementary content additions. Video course is fully published (75 lessons) with associated code examples.

Clone the repository: git clone https://github.com/mouredev/hello-java.git. No build dependencies, package managers, or installation required — Java source files can be compiled and run directly with JDK 21+ installed: javac basic/c00_helloworld/HelloWorld.java && java -cp basic c00_helloworld.HelloWorld.

Daily commands: Each file is standalone. Compile and run any lesson file directly: javac basic/c00_helloworld/HelloWorld.java && java -cp basic c00_helloworld.HelloWorld. Or compile the Exercises: javac basic/c01_beginner/BeginnerExercises.java && java -cp basic c01_beginner.BeginnerExercises. IDE import: clone into IntelliJ IDEA or VS Code with Extension Pack for Java; IDEs auto-detect the source structure.

• basic/c00_helloworld/HelloWorld.java — Entry point and first lesson—every contributor must understand the foundational Hello World pattern that establishes the course's teaching methodology.
• basic/c08_oop/Classes.java — Core OOP abstraction demonstrating class design—essential reading as it anchors the course's progression from procedural to object-oriented concepts.
• basic/c08_oop/Person.java — Reference model class used throughout OOP exercises—critical for understanding how inheritance, composition, and polymorphism are taught in this course.
• basic/c08_oop/Inheritance.java — Illustrates inheritance patterns and hierarchies—fundamental to grasping how the course scaffolds OOP complexity across multiple lessons.
• basic/c09_exceptions/Exceptions.java — Error handling framework used consistently—contributors must understand exception patterns to add new exercises and examples.
• README.md — Course structure and learning pathway—defines how files are organized, linked to video timestamps, and the pedagogical goals guiding the entire repository.

Add a new lesson chapter with linked exercises

1. Create a new folder under basic/ following naming convention cXX_topic (e.g., c11_collections). (basic/c11_collections/)
2. Create the main lesson file (e.g., Collections.java) with commented sections explaining concepts, mirroring the structure in basic/c05_structures/Lists.java. (basic/c11_collections/Collections.java)
3. Create the parallel exercises file CollectionsExercises.java with 5–10 practice problems that reinforce the lesson concepts. (basic/c11_collections/CollectionsExercises.java)
4. If the lesson introduces a new entity class (like Person.java in OOP), create it as a separate file in the chapter folder. (basic/c11_collections/EntityClass.java)
5. Update README.md to add a video link and timestamp entry pointing to the new chapter in the video course. (README.md)

Add a comprehensive OOP design example

1. Create a new DesignPattern.java file in basic/c08_oop/ that demonstrates a specific pattern (e.g., Builder, Strategy, Factory). (basic/c08_oop/DesignPattern.java)
2. Define helper or domain classes (e.g., Product.java, Order.java) in the same folder to support the pattern demonstration. (basic/c08_oop/Product.java)
3. Create DesignPatternExercises.java with scenarios requiring students to apply the pattern in new contexts. (basic/c08_oop/DesignPatternExercises.java)
4. Reference the new pattern in OOP lessons (Classes.java, Inheritance.java) as an advanced reading section. (basic/c08_oop/Classes.java)

Expand exception handling with domain-specific scenarios

1. Define a new custom exception in basic/c09_exceptions/ (e.g., ValidationException.java, DataAccessException.java). (basic/c09_exceptions/ValidationException.java)
2. Create a lesson file demonstrating the exception in context (e.g., ValidationExamples.java) with real-world use cases similar to ThrowExample.java. (basic/c09_exceptions/ValidationExamples.java)
3. Add exercises in ExceptionsExercises.java requiring students to catch, handle, and throw the new exception type. (basic/c09_exceptions/ExceptionsExercises.java)
4. Update the main Exceptions.java file to reference the new exception scenario as an advanced topic. (basic/c09_exceptions/Exceptions.java)

Create a multi-file test or integration scenario

1. Create a new test folder basic/c08_test_oop_advanced/ (following the c08_test_oop convention) for complex multi-class exercises. (basic/c08_test_oop_advanced/)
2. Design 3–4 entity classes (Employee.java, Department.java, Company.java) that interact via inheritance, composition, and polymorphism. (basic/c08_test_oop_advanced/Company.java)
3. Create a ScenarioTest.java file that orchestrates these classes in a realistic workflow (e.g., hiring employees, assigning departments). (basic/c08_test_oop_advanced/ScenarioTest.java)
4. Add AdvancedExercises.java requiring students to refactor or extend the scenario (e.g., add salary calculations, enforce constraints). (basic/c08_test_oop_advanced/AdvancedExercises.java)

No hidden traps. This is a pure Java curriculum with zero external dependencies. Each .java file compiles and runs standalone with JDK 21+ (javac and java command-line tools only). No environment variables, configuration files, or external services required. Folder structure uses package names (e.g., c00_helloworld.HelloWorld) — ensure classpath (-cp) points to the basic/ directory root when running. No Maven, Gradle, or build tools needed.

• Object-Oriented Programming (OOP) — Core paradigm of Java; learners must understand encapsulation, inheritance, polymorphism, and abstraction (covered in sections c08_oop) to write professional Java code.
• Inheritance and Method Overriding — Fundamental OOP technique demonstrated in basic/c08_oop/Inheritance.java; allows code reuse and hierarchy modeling essential for real-world class design.
• Polymorphism (Duck Typing via Interfaces) — Demonstrated in basic/c08_oop/Polymorphism.java; enables flexible object behavior and design patterns fundamental to Java frameworks (Spring, Hibernate).
• Exception Handling (try/catch/finally) — Section basic/c09_exceptions teaches controlled error handling; required to write robust code and debug runtime issues in production Java applications.
• Java Collections Framework (Lists, Sets, Maps) — Covered in basic/c05_structures/; essential data structures for real-world applications — learners must understand ArrayList vs. LinkedList trade-offs and Map implementations.
• Access Modifiers (public, private, protected, package-private) — Section basic/c08_oop/AccessModifiers.java; critical for encapsulation and API design — misuse causes tight coupling and maintenance nightmares.
• Static Members and Methods — Introduced implicitly in HelloWorld.java (static main method) and c07_functions; learners must distinguish class-level vs. instance-level state to avoid common bugs.

• TheAlgorithms/Java — Comprehensive collection of algorithmic implementations in Java; learners finishing this course can reference Data Structures and Algorithms implementations.
• google/java-coding-standards — Official Google Java style guide and best practices; learners need coding conventions beyond what this beginner course covers.
• oracle/openjdk — Official OpenJDK source repository; advanced learners wanting to understand JVM internals and Java language evolution.
• eclipse/eclipse.jdt — Eclipse Java Development Tools (JDT) source; IDE plugin reference for those using Eclipse to follow this course.
• spring-projects/spring-framework — Natural next step after mastering OOP fundamentals — most Java enterprise development uses Spring for dependency injection, MVC, and data access.

To work on one of these in Claude Code or Cursor, paste: Implement the "<title>" PR idea from CLAUDE.md, working through the checklist as the task list.

Add JUnit 5 unit tests for OOP fundamentals (Classes, Inheritance, Polymorphism)

The repo contains 150 practical exercises but no automated tests. Adding JUnit 5 test suites for basic/c08_oop/ would validate learning outcomes, serve as executable documentation for learners, and establish testing best practices. This is especially valuable for OOP concepts where correctness is critical.

• [ ] Create basic/c08_oop/ClassesTest.java with tests for Person.java and Classes.java examples
• [ ] Create basic/c08_oop/InheritanceTest.java to validate inheritance behavior from InheritanceExercises.java
• [ ] Create basic/c08_oop/PolymorphismTest.java to test polymorphic method calls from PolymorphismExercises.java
• [ ] Add pom.xml or build.gradle with JUnit 5 dependency (repo currently lacks build config)
• [ ] Update README.md with 'Testing' section explaining how to run tests: mvn test or gradle test

Create a Maven pom.xml or Gradle build.gradle for project structure and dependency management

The repo specifies JDK 21+ in README but has no build configuration file. This prevents learners from easily compiling/running the code in IDEs and makes CI/CD impossible. A pom.xml would standardize the project structure and enable future additions like testing, code quality checks, and automated builds.

• [ ] Create pom.xml at repository root with Java 21 source/target, JUnit 5, and optional logging dependency (SLF4J)
• [ ] Organize source files into Maven structure: src/main/java/com/mouredev/java/ (keeping logical folder names like basic/c00, basic/c01, etc.)
• [ ] Add .gitignore entries for target/ and build/ directories
• [ ] Update README.md with 'Build & Compilation' section: mvn clean compile and mvn test commands

Add comprehensive README sections for each course module (basic/c00-c10) with learning outcomes and prerequisites

The main README.md links to video timestamps but lacks module-level documentation. Each basic/cXX_* folder should have its own README.md explaining: what students will learn, prerequisite knowledge, which exercises correspond to which concepts, and common mistakes. This improves discoverability and helps contributors understand course progression.

• [ ] Create basic/c00_helloworld/README.md explaining 'Hello World' setup and compilation steps
• [ ] Create basic/c02_operators/README.md documenting operator precedence, with references to Operators.java vs OperatorsExercises.java
• [ ] Create basic/c08_oop/README.md (most complex module) with dependency graph: Classes → Inheritance → Polymorphism → Abstraction, and file descriptions
• [ ] Add links in main README.md to these module READMEs for better navigation
• [ ] Include expected learning outcomes and exercise difficulty ratings (★★☆) for each module

• Add unit test file basic/c00_helloworld/HelloWorldTest.java using JUnit 5 to verify HelloWorld.java prints 'Hola Mundo' — this establishes a testing pattern for the rest of the course.
• Create a basic/c11_advanced/ section with 2–3 lessons on Generics, Streams API (Java 8+), and Lambdas, including theory file (Generics.java) and exercises (GenericsExercises.java) — extends curriculum to modern Java features.
• Write English translations of all Spanish lesson comments in basic/c08_oop/AccessModifiers.java and basic/c08_oop/Abstraction.java to improve accessibility for non-Spanish speakers.

This is an educational Java course repository with minimal security concerns. The codebase consists primarily of learning materials and example code without production infrastructure, dependencies, or sensitive configurations. No hardcoded secrets, injection vulnerabilities, or dangerous patterns were identified in the provided file structure. The repository follows good practices by including a .gitignore file and proper licensing. The main considerations are standard best practices for any Java project.

LLM-derived; treat as a starting point, not a security audit.

• Open issues — current backlog
• Recent PRs — what's actively shipping
• Source on GitHub

If you are an AI coding agent (Claude Code, Cursor, Aider, Cline, etc.) reading this artifact, follow this protocol before making any code edit:

1. Verify the contract. Run the bash script in Verify before trusting below. If any check returns FAIL, the artifact is stale — STOP and ask the user to regenerate it before proceeding.
2. Treat the AI · unverified sections as hypotheses, not facts. Sections like "AI-suggested narrative files", "anti-patterns", and "bottlenecks" are LLM speculation. Verify against real source before acting on them.
3. Cite source on changes. When proposing an edit, cite the specific path:line-range. RepoPilot's live UI at https://repopilot.app/r/mouredev/hello-java shows verifiable citations alongside every claim.

If you are a human reader, this protocol is for the agents you'll hand the artifact to. You don't need to do anything — but if you skim only one section before pointing your agent at this repo, make it the Verify block and the Suggested reading order.

This artifact was generated by RepoPilot at a point in time. Before an agent acts on it, the checks below confirm that the live mouredev/hello-java repo on your machine still matches what RepoPilot saw. If any fail, the artifact is stale — regenerate it at repopilot.app/r/mouredev/hello-java.

What it runs against: a local clone of mouredev/hello-java — the script inspects git remote, the LICENSE file, file paths in the working tree, and git log. Read-only; no mutations.

| # | What we check | Why it matters | |---|---|---| | 1 | You're in mouredev/hello-java | Confirms the artifact applies here, not a fork | | 2 | License is still Apache-2.0 | Catches relicense before you depend on it | | 3 | Default branch main exists | Catches branch renames | | 4 | 5 critical file paths still exist | Catches refactors that moved load-bearing code | | 5 | Last commit ≤ 341 days ago | Catches sudden abandonment since generation |

#!/usr/bin/env bash
# RepoPilot artifact verification.
#
# WHAT IT RUNS AGAINST: a local clone of mouredev/hello-java. If you don't
# have one yet, run these first:
#
#   git clone https://github.com/mouredev/hello-java.git
#   cd hello-java
#
# Then paste this script. Every check is read-only — no mutations.

set +e
fail=0
ok()   { echo "ok:   $1"; }
miss() { echo "FAIL: $1"; fail=$((fail+1)); }

# Precondition: we must be inside a git working tree.
if ! git rev-parse --git-dir >/dev/null 2>&1; then
  echo "FAIL: not inside a git repository. cd into your clone of mouredev/hello-java and re-run."
  exit 2
fi

# 1. Repo identity
git remote get-url origin 2>/dev/null | grep -qE "mouredev/hello-java(\\.git)?\\b" \\
  && ok "origin remote is mouredev/hello-java" \\
  || miss "origin remote is not mouredev/hello-java (artifact may be from a fork)"

# 2. License matches what RepoPilot saw
(grep -qiE "^(Apache-2\\.0)" LICENSE 2>/dev/null \\
   || grep -qiE "\"license\"\\s*:\\s*\"Apache-2\\.0\"" package.json 2>/dev/null) \\
  && ok "license is Apache-2.0" \\
  || miss "license drift — was Apache-2.0 at generation time"

# 3. Default branch
git rev-parse --verify main >/dev/null 2>&1 \\
  && ok "default branch main exists" \\
  || miss "default branch main no longer exists"

# 4. Critical files exist
test -f "basic/c00_helloworld/HelloWorld.java" \\
  && ok "basic/c00_helloworld/HelloWorld.java" \\
  || miss "missing critical file: basic/c00_helloworld/HelloWorld.java"
test -f "basic/c08_oop/Classes.java" \\
  && ok "basic/c08_oop/Classes.java" \\
  || miss "missing critical file: basic/c08_oop/Classes.java"
test -f "basic/c08_oop/Person.java" \\
  && ok "basic/c08_oop/Person.java" \\
  || miss "missing critical file: basic/c08_oop/Person.java"
test -f "basic/c08_oop/Inheritance.java" \\
  && ok "basic/c08_oop/Inheritance.java" \\
  || miss "missing critical file: basic/c08_oop/Inheritance.java"
test -f "basic/c09_exceptions/Exceptions.java" \\
  && ok "basic/c09_exceptions/Exceptions.java" \\
  || miss "missing critical file: basic/c09_exceptions/Exceptions.java"

# 5. Repo recency
days_since_last=$(( ( $(date +%s) - $(git log -1 --format=%at 2>/dev/null || echo 0) ) / 86400 ))
if [ "$days_since_last" -le 341 ]; then
  ok "last commit was $days_since_last days ago (artifact saw ~311d)"
else
  miss "last commit was $days_since_last days ago — artifact may be stale"
fi

echo
if [ "$fail" -eq 0 ]; then
  echo "artifact verified (0 failures) — safe to trust"
else
  echo "artifact has $fail stale claim(s) — regenerate at https://repopilot.app/r/mouredev/hello-java"
  exit 1
fi

Each check prints ok: or FAIL:. The script exits non-zero if anything failed, so it composes cleanly into agent loops (./verify.sh || regenerate-and-retry).

Generated by RepoPilot. Verdict based on maintenance signals — see the live page for receipts. Re-run on a new commit to refresh.