Gradle Tasks and Lifecycle

1. Gradle Lifecycle

Gradle's lifecycle describes how a build runs from start to finish. It has three main phases:

1. Initialization Phase

Gradle determines which projects are involved in the build.

Gradle finds the root project (where settings.gradle or settings.gradle.kts lives).
It evaluates settings.gradle to discover all included subprojects.
It creates a Project object for each project.

Example: A multi-module project creates multiple Project instances here.

2. Configuration Phase

Gradle configures the build for all projects included in the build.

What happens:

Gradle runs all the build scripts (build.gradle, build.gradle.kts) to configure tasks.
Task objects are created and configured.
Dependency graphs for tasks are built.

Output: A fully configured build with all tasks ready, but no tasks have run yet.

3. Execution Phase

Gradle executes only the tasks requested on the command line.

Example: :moduleA:build

2. Gradle Tasks

A Gradle task is a single job in the build process. It could be any task like compiling code, running tests, creating a package or uploading files. These tasks are defined in a build script (build.gradle).

Types of Gradle Tasks

Gradle provides two main types of tasks which are listed below:

1. Built-In Tasks:

Built-In Tasks are tasks that come pre-configured with gradle. Common built-in tasks include:

build: It compiles and assembles the project.
clean: It deletes the build directory.
test: It runs unit tests for the project.
jar: It creates a JAR file from the compiled classes.

2. Custom Tasks:

Custom tasks are tasks that we define in our build.gradle file. We can create a task to automate any action that Gradle does not handle by default.

Example:

task helloWorld {
    doLast {
        println 'Welcome to the homePath'
    }
}

Output: This task will print a message when you run it.