# Task Basics

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A task represents some independent unit of work that a build performs, such as compiling classes, creating a JAR, generating Javadoc, or publishing archives to a repository.

You run a Gradle `build` task using the `gradle` command or by invoking the Gradle Wrapper (`./gradlew` or `gradlew.bat`) in your project directory:

    $ ./gradlew build

## Available tasks

All available tasks in your project come from Gradle plugins and build scripts.

You can list all the available tasks in the project by running the following command in the terminal:

    $ ./gradlew tasks

    Application tasks
    -----------------
    run - Runs this project as a JVM application

    Build tasks
    -----------
    assemble - Assembles the outputs of this project.
    build - Assembles and tests this project.

    ...

    Documentation tasks
    -------------------
    javadoc - Generates Javadoc API documentation for the main source code.

    ...

    Other tasks
    -----------
    compileJava - Compiles main Java source.

    ...

## Running tasks

The `run` task is executed with `./gradlew run`:

    $ ./gradlew run

    > Task :app:compileJava
    > Task :app:processResources NO-SOURCE
    > Task :app:classes

    > Task :app:run
    Hello World!

    BUILD SUCCESSFUL in 904ms
    2 actionable tasks: 2 executed

In this example Java project, the output of the `run` task is a `Hello World` statement printed on the console.

## Task dependency

Many times, a task requires another task to run first.

For example, for Gradle to execute the `build` task, the Java code must first be compiled. Thus, the `build` task depends on the `compileJava` task.

This means that the `compileJava` task will run before the `build` task:

    $ ./gradlew build

    > Task :app:compileJava
    > Task :app:processResources NO-SOURCE
    > Task :app:classes
    > Task :app:jar
    > Task :app:startScripts
    > Task :app:distTar
    > Task :app:distZip
    > Task :app:assemble
    > Task :app:compileTestJava
    > Task :app:processTestResources NO-SOURCE
    > Task :app:testClasses
    > Task :app:test
    > Task :app:check
    > Task :app:build

    BUILD SUCCESSFUL in 764ms
    7 actionable tasks: 7 executed

Build scripts can optionally define task dependencies. Gradle then automatically determines the task execution order.

Consult the Task development chapter to learn more.

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