Java 8+ Practice Project

A hands-on learning project exploring Java 8+ features through practical, real-world examples.
Topics covered: Optional, Function (Functional Interface), JUnit 5 tagging, and CI/CD basics.

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📚 What Is This Project?

See docs/WHAT_IS_IT.md for a full overview of the project goals and structure.

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📂 Project Structure

src/
├── main/java/
│ ├── functionalInterface/function/myimpl/ ← Function<T,R> interface demo
│ ├── optionaldemoone/ ← Optional with real-world domain objects
│ └── jenkins/ ← CI/CD placeholder
└── test/java/
├── junitdemo/ ← JUnit 5 Tags & Display Names
├── optionaldemoone/ ← Tests for DiscountService
└── optionaldemoWithPerson/ ← Optional stream scenarios

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🗂️ Learning Guides

Guide	Description
docs/WHAT_IS_IT.md	Project overview and learning goals
docs/optional-guide.md	Deep dive into Java Optional
docs/advanced-optional-scenarios-explained.md	Advanced Optional patterns explained in depth
docs/functional-interface-function-guide.md	Function<T,R>, andThen, compose
docs/junit5-tagging-guide.md	JUnit 5 @Tag, @DisplayName, selective test runs
docs/java21-modern-java-guide.md	Java 21 features used in this project
docs/github-actions-guide.md	GitHub Actions explained for beginners
docs/github-actions-advanced-guide.md	Advanced GitHub Actions — concurrency, secrets, matrix, artifacts, reusable workflows

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🚀 Running the Project

Prerequisites

• Java 21+
• Maven 3.6+

Run All Tests (locally)

mvn test

Run Tests by Tag (locally)

# Run integration tests only
mvn test -Dgroups="integration"# Run unit tests only
mvn test -Dgroups="ecomm-unit-tests"# Run sanity tests only
mvn test -Dgroups="ecomm-sanity"# Run Optional demo tests
mvn test -Dgroups="Rel1"

Pass Custom System Properties

mvn test -DinParameter=MyValue

🤖 Run via GitHub Actions (CI/CD)

Workflow	Trigger	What it runs
CI — Build & Test All	Auto on every push & PR	All tests
Ecommerce — Unit Tests	Manual (Actions tab)	@Tag("ecomm-unit-tests")
Ecommerce — Sanity Tests	Manual (Actions tab)	@Tag("ecomm-sanity")
Run Tests by Tag	Manual with input	Any tag you specify

📖 New to GitHub Actions? See docs/github-actions-guide.md for a full walkthrough.

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🛠️ Tech Stack

Technology	Version	Purpose
Java	21 (LTS)	Language — enables records, switch expressions, var, .toList(), text blocks, and more
Maven	3.6+	Build tool
JUnit Jupiter	5.10.2	Unit testing framework
AssertJ	3.19.0	Fluent assertions