Gradle Tasks

Introduction

Gradle builds are graphs of tasks—compile, test, jar, and your own steps. Tasks declare inputs and outputs so Gradle can skip work (incremental builds) and cache results. This chapter covers built-in Java tasks, common CLI commands, and simple custom tasks.

Prerequisites

• Dependency management
• Build script basics

Task Model

Each task has:

• Actions — code in doFirst / doLast or plugin logic
• Dependencies — other tasks that must run first
• Inputs/outputs — files and properties for up-to-date checks

compileJava  ──dependsOn──>  processResources
test         ──dependsOn──>  classes
jar          ──dependsOn──>  classes
build        ──dependsOn──>  assemble, check

Unlike Maven’s fixed phases, you can insert tasks anywhere in the graph.

List Tasks

./gradlew tasks
./gradlew tasks --group=build

Shows description, group, and dependencies for discovery.

Common Built-in Tasks (Java Plugin)

./gradlew build
./gradlew test
./gradlew clean build

Skip Tests

./gradlew build -x test

Debug Failed Builds

./gradlew build --stacktrace
./gradlew build --info
./gradlew build --scan

--stacktrace prints the root cause; --info logs more detail.

Task Dependencies in Scripts

tasks.named('test') {
    dependsOn 'integrationTest'
}

Ordering without dependency:

tasks.named('publish') {
    mustRunAfter 'test'
}

mustRunAfter does not force test to run—only orders if both execute.

Register a Custom Task

tasks.register('hello') {
    group = 'sample'
    description = 'Print a greeting'
    doLast {
        println 'Hello from a custom task'
    }
}

./gradlew hello

Copy Files Example

tasks.register('copyReadme', Copy) {
    group = 'distribution'
    from('README.md')
    into("$buildDir/dist")
}

./gradlew copyReadme

Built-in task types (Copy, Delete, Exec) encapsulate common work.

doFirst and doLast

tasks.named('test') {
    doFirst {
        println 'Starting tests...'
    }
    doLast {
        println 'Tests finished.'
    }
}

Compare with Maven Phases

Gradle has more granular task names; build is the usual “do everything” entry.

Mini Example: Zip Dist Folder

tasks.register('distZip', Zip) {
    group = 'distribution'
    dependsOn 'jar'
    archiveFileName = 'app-dist.zip'
    destinationDirectory = layout.buildDirectory.dir('dist')
    from jar.outputs.files
    from('README.md')
}

./gradlew distZip

FAQ

Task vs plugin?

Plugins register many tasks and wire them together. You call tasks; plugins provide the graph.

Why did compileJava run but not test?

You invoked a specific task—dependencies still run; unrelated branches may skip.

Parallel execution?

Gradle runs independent tasks in parallel when org.gradle.parallel=true.

What comes next?

Gradle plugins.