Task Actions in Gradle (Execution Phase)

Overview

Gradle tasks are composed of actions, which are units of work that are executed in a specific order. This note covers the key methods for defining actions in Gradle tasks:

• doLast
• doFirst

Key Methods for Defining Task Actions

doLast

The doLast method adds an action to the end of a task’s execution phase.

This action is executed after all other actions defined in the task have completed.

Usage Example:

tasks.register("exampleTask") {
    doLast {
        println("This action runs after the main task actions.")
    }
}

Syntax: <<

Operator '<<' IS do last

Note: the ”<<” is a shorthand notation for “doLast”

task B << {
 println 'action'
}

ref

Link to original

doFirst

doFirst

The doFirst method adds an action to the beginning of a task’s execution phase. This action is executed before all other actions defined in the task.

Usage Example:

tasks.register("exampleTask") {
    doFirst {
        println("This action runs before the main task actions.")
    }
}

Link to original

Key Points

1. Execution Order:
   • doFirst actions are executed first.
   • doLast actions are executed last.

Example in Context

In a task that prepares a file for logging test results, these methods can ensure the file is properly managed before and after the main task actions:

tasks.register("actionsEg") {
    doFirst {
        println("doFirst-3 will be executed THIRD")
    }
    doFirst {
        println("doFirst-2 will be executed SECOND")
    }
    doLast {
        println("doLast will be executed FOURTH")
    }
    doFirst {
        println("doFirst-1 - will be executed FIRST")
    }
}

Glass thought Sandbox Snapshot

Command to reproduce:

gt.sandbox.checkout.commit 3102345 \
&& cd "${GT_SANDBOX_REPO}" \
&& cmd.run.announce "./gradlew actionsEg"

Recorded output of command:

 
> Task :lib:actionsEg
doFirst-1 - will be executed FIRST
doFirst-2 will be executed SECOND
doFirst-3 will be executed THIRD
doLast will be executed FOURTH
 
BUILD SUCCESSFUL in 359ms
1 actionable task: 1 executed

Reverse order

Multiple doFirst and doLast blocks are executed in the reverse order they are defined

• Just avoid having multiple doFirst or doLast in the same task