Introduction to Gradle

What is Gradle?

• Gradle is a build tool, also known as a build automation tool.
• It is primarily used for building Java applications.
• Offers productivity benefits over other build tools.

Why Use Build Tools?

• Transform Java source code into executable applications.
• Compile Java files into bytecode, run on JVM.
• Handle dependencies and resources efficiently.
• Make compilation error-free and repeatable.
• Automate testing and packaging processes.

Gradle vs Manual Compilation

• Manual compilation is tedious and error-prone.
• Gradle simplifies compiling, testing, and packaging with single commands.
• Uses a build script to describe application configurations.

Benefits of Using Gradle

• Fast and efficient processing with features like incremental build.
• Advanced dependency management system.
• More efficient than creating custom build scripts.

Gradle vs Maven

• Maven was advanced but Gradle is faster and less verbose.
• Gradle uses code-based scripts, easier plugin writing, and logic reuse.
• Most popular build tool for JVM projects on GitHub.

Getting Started with Gradle

Prerequisites

• Java version 8 or above.
• Installation of Gradle (steps detailed).

Creating a Gradle Project

Initial Setup

• Create a directory for your project.
• Use gradle init to set up the project.
• Contains key files: settings.gradle, build.gradle, gradle wrapper scripts, .gitignore.

Key Files

• settings.gradle: Configures project name.
• build.gradle: Core build configuration.
• gradle wrapper scripts: Enable building without explicit Gradle installation.
• .gitignore: Ensures certain directories aren't version-controlled.

Understanding Gradle Components

• Projects: Highest level, includes everything about the app.
• Build Scripts: Configuration files for building projects.
• Tasks: Individual build actions (e.g., compile, test, package).
• Plugins: Extend functionality by adding tasks.

Writing a Build Script

Using Groovy for Build Scripts

• Groovy allows concise configuration.
• Key features: dynamic typing, optional semicolons, closure definitions.

Building a Java Application

1. Create Java Class: Add source file in source/main/java.
2. Apply Java Plugin: Adds compile, test, package tasks.
3. Run Build Task: Compiles Java source to class files and creates JAR.
4. Configure Manifest: Add main class to JAR manifest for execution.

Adding Tests

• Tests go in source/test/java.
• Use JUnit for testing.
• Add dependencies and repositories in build.gradle.

Conclusion

• Gradle simplifies building, testing, and packaging Java applications.
• It automates dependency management and task execution.
• A powerful tool for any Java developer.