Gradle

Concept: Gradle

Purpose:

Gradle is a versatile build automation tool, often used for Java, Kotlin, and Android projects. It automates tasks like

  • compiling code
  • managing dependencies
  • running tests
  • packaging applications.

It can handle almost any language or environment with its flexible configuration and plugin system.

Key Concepts:

1. Gradle Build Scripts

Gradle uses Domain-Specific Languages (DSL) for defining build scripts.

  • Groovy or Kotlin DSL: Build scripts can be written in Groovy (build.gradle) or Kotlin (build.gradle.kts).

  • Tasks: Everything in Gradle revolves around tasks. Tasks can:

    • Execute commands like compiling code.
    • Run unit tests.
    • Package applications (e.g., .jar, .war).
  • Build Lifecycle:

    • Initialization: Determines which project to build.
    • Configuration: Evaluates project scripts and sets up a task graph.
    • Execution: Executes tasks based on the task graph.

2. Dependency Management

Gradle simplifies managing dependencies for a project by automatically downloading and managing external libraries.

  • Repositories: Gradle looks for dependencies in specified repositories, such as Maven Central, JCenter, or custom repositories.
  • Configurations: Logical groupings of dependencies. Common ones include:
    • implementation: For compiling the main code.
    • testImplementation: For test-specific dependencies.
  • Scopes:
    • Compile-time: Dependencies available during compilation.
    • Runtime: Dependencies available only during runtime.
    • Test: Dependencies available only for testing.

Example:

repositories {
    mavenCentral()
}

dependencies {
    implementation("org.jetbrains.kotlin:kotlin-stdlib:1.8.0")
    testImplementation("junit:junit:4.13.2")
}

3. Plugins

Gradle can be extended with plugins that add specific functionality, enabling tasks like building Java projects or working with Android.

  • Core Plugins: Built-in plugins like java, kotlin, application.
  • Third-Party Plugins: External plugins from Gradle Plugin Portal or custom plugins.
  • Custom Plugins: You can create custom plugins to extend build behavior.

Example:

plugins {
    id("org.jetbrains.kotlin.jvm") version "1.8.0"
    id("application")
}

4. Multi-Project Builds

Gradle supports organizing large projects into multiple smaller subprojects that share configurations.

  • Settings File (settings.gradle.kts): This file defines which projects belong to the build.
  • Subprojects: Subprojects can have their own build scripts or inherit from the root build script.

Example:

rootProject.name = "my-multi-project"
include("projectA", "projectB")

5. Task Configuration

Tasks are central to Gradle’s functioning. You can create, configure, and control task execution.

  • Custom Tasks: You can define tasks to perform specific actions.
  • Task Dependencies: You can specify dependencies between tasks to control their execution order.

Example of a Custom Task:

tasks.register("hello") {
    doLast {
        println("Hello, Gradle!")
    }
}
  • Task Inputs and Outputs: Gradle optimizes task execution by caching outputs based on inputs to avoid redundant executions.

6. Gradle Wrapper

The Gradle Wrapper (gradlew) ensures the project uses a specific version of Gradle without requiring local installation.

  • Installation: The Wrapper is created using the gradle wrapper command.
  • Usage: Execute ./gradlew build instead of gradle build to use the wrapper and guarantee consistent builds across environments.

Example:

./gradlew clean build

Use Case:

Gradle is highly customizable and widely used in:

  • Java/Kotlin Projects: For building and testing Java or Kotlin applications.
  • Android Development: As the default build tool for Android apps.
  • Continuous Integration/Deployment: Integrated into CI/CD pipelines with tools like Jenkins, GitLab CI, and others.

Children
  1. Commands
  2. Concept
  3. Examples
  4. Files
  5. Gists
  6. Lang
  7. Mindmap
  8. Old
  9. Plugins
  10. Ref
  11. Setup
  12. Snippets
  13. Values
  14. What Defines Gradle Output
  15. gradle kotlin-mp
  16. publishToMavenLocal