Attività e ciclo di vita della build

Welcome! In this lesson, we'll dive into Gradle Tasks, the fundamental units of work in any Gradle build.

• A task represents a single, atomic piece of work that Gradle performs.
• Think of tasks as actions like 'compile code', 'run tests', 'clean build directory', or 'deploy application'.
• They are the building blocks that make up your entire build process.

Gradle comes with many built-in tasks. You can list all available tasks for your project using the command line:

gradle tasks

This command shows a categorized list of tasks, including those provided by plugins and any custom tasks you define. It's a great way to explore what your build can do!

Creating your own custom task is straightforward in your build.gradle file. Let's define a simple task:

The task keyword is used, followed by the task's name. The curly braces {} define the task's actions.

To execute a custom task, you simply run Gradle from your terminal, specifying the task name:

gradle helloWorld

When you run the example from the previous scene, you'll see "Hello from CoddyKit Gradle!" printed in the console.

Tasks can have multiple actions. You can define these actions using doLast and doFirst blocks.

• doLast: Adds an action to be executed at the end of the task.
• doFirst: Adds an action to be executed at the beginning of the task.

These are useful for organizing complex task logic.

Often, one task must complete before another can start. Gradle handles this with task dependencies using the dependsOn keyword.

If task 'B' depends on task 'A', then 'A' will always run before 'B'. This ensures operations happen in the correct order.

Every time you run a Gradle command, it goes through a distinct build lifecycle, consisting of three main phases:

1. Initialization: Sets up the build environment.
2. Configuration: Evaluates build scripts and configures tasks.
3. Execution: Runs the configured tasks.

Understanding these phases is key to writing effective Gradle builds.

The Initialization Phase is where Gradle determines which projects are participating in the build.

• It evaluates the settings.gradle file (if present).
• This file defines the project hierarchy for multi-project builds.
• Gradle creates a Project instance for each project involved.

This phase essentially sets the stage for the build.

During the Configuration Phase, all build.gradle scripts for the projects are evaluated.

• Tasks are created and configured.
• Important: Any code directly in a task block (not inside doLast or doFirst) runs during this phase, regardless of whether the task will actually be executed.

This is where tasks' properties and dependencies are set up.

The final phase is the Execution Phase. This is where the actual work happens!

• Gradle determines which tasks need to run based on your command and task dependencies.
• It then executes the doFirst and doLast actions (and any other actions) of those selected tasks.
• Tasks are executed in the correct order, respecting their dependencies.

This is when your code compiles, tests run, and artifacts are built.

Great job! You've learned the core concepts of Gradle tasks and the build lifecycle:

• Tasks are the fundamental units of work.
• You can define custom tasks and chain them with dependsOn.
• The Gradle build proceeds through three phases: Initialization, Configuration, and Execution.
• Code directly in a task block runs during Configuration, while doFirst/doLast actions run during Execution.

Next, we'll explore how Gradle manages external dependencies!