The Build Init plugin can be used to create a new Gradle build. It supports creating brand new Gradle builds of various types as well as converting existing Apache Maven builds to Gradle.

Sample usage

gradle init \
  --type java-application \
  --dsl kotlin \
  --test-framework junit-jupiter \
  --package my.project \
  --project-name my-project  \
  --no-split-project  \
  --java-version 17

Gradle enters interactive mode and prompts the user when a required parameter for the selected project type is missing.

Supported Gradle build types

The Build Init plugin supports generating various build types. These are listed below and more detail is available about each type in the following section.

Table 1. Build init types
Type Description

pom

Converts an existing Apache Maven build to Gradle

basic

A basic, empty, Gradle build

java-application

A command-line application implemented in Java

java-gradle-plugin

A Gradle plugin implemented in Java

java-library

A Java library

kotlin-application

A command-line application implemented in Kotlin/JVM

kotlin-gradle-plugin

A Gradle plugin implemented in Kotlin/JVM

kotlin-library

A Kotlin/JVM library

groovy-application

A command-line application implemented in Groovy

groovy-gradle-plugin

A Gradle plugin implemented in Groovy

groovy-library

A Groovy library

scala-application

A Scala application

scala-library

A Scala library

cpp-application

A command-line application implemented in C++

cpp-library

A C++ library

Tasks

The plugin adds the following tasks to the project:

init — InitBuild

Generates a Gradle build.

Gradle plugins usually need to be applied to a project before they can be used (see Using plugins). However, the Build Init plugin is automatically applied to the root project of every build, which means you do not need to apply it explicitly in order to use it. You can simply execute the task named init in the directory where you would like to create the Gradle build. There is no need to create a “stub” build.gradle file in order to apply the plugin.

What to create

The simplest, and recommended, way to use the init task is to run gradle init from an interactive console. Gradle will list the available build types and ask you to select one. It will then ask some additional questions to allow you to fine-tune the result.

There are several command-line options available for the init task that control what it will generate. You can use these when Gradle is not running from an interactive console. You can see available options using the help task:

gradle help --task init

The build type can be specified by using the --type command-line option. For example, to create a Java library project run:

gradle init --type java-library

If a --type option is not provided, Gradle will attempt to infer the type from the environment. For example, it will infer a type of “pom” if it finds a pom.xml file to convert to a Gradle build. If the type could not be inferred, the type “basic” will be used.

The init task also supports generating build scripts using either the Gradle Kotlin DSL or the Gradle Groovy DSL. The build script DSL defaults to the Kotlin DSL for most build types and to the Groovy DSL for Groovy build types. The DSL can be selected by using the --dsl command-line option.

For example, to create a Java library project with Kotlin DSL build scripts, run:

gradle init --type java-library --dsl kotlin

You can change the name of the generated project using the --project-name option. It defaults to the name of the directory where the init task is run.

You can change the package used for generated source files using the --package option. It defaults to the project name.

If the --incubating option is provided, Gradle will generate build scripts which may use the latest versions of APIs, which are marked @Incubating and remain subject to change. To disable this behavior, use --no-incubating.

If the --overwrite option is provided, Gradle will overwrite any existing files in the directory where the init task runs. By default, init will prompt the user to continue if Gradle finds any files in the directory.

All build types also set up Gradle Wrapper in the build.

Build init types

pom build type (Maven conversion)

The “pom” type can be used to convert an Apache Maven build to a Gradle build. This works by converting the POM to one or more Gradle files. It is only able to be used if there is a valid “pom.xml” file in the directory that the init task is invoked in or, if invoked via the “-p” command line option, in the specified project directory. This “pom” type will be automatically inferred if such a file exists.

The Maven conversion implementation was inspired by the maven2gradle tool that was originally developed by Gradle community members.

The conversion process has the following features:

  • Uses effective POM and effective settings (support for POM inheritance, dependency management, properties)

  • Supports both single module and multimodule projects

  • Supports custom module names (that differ from directory names)

  • Generates general metadata - id, description and version

  • Applies Maven Publish, Java Library and War Plugins (as needed)

  • Supports packaging war projects as jars if needed

  • Generates dependencies (both external and inter-module)

  • Generates download repositories (inc. local Maven repository)

  • Adjusts Java compiler settings

  • Supports packaging of sources, tests, and javadocs

  • Supports TestNG runner

  • Generates global exclusions from Maven enforcer plugin settings

  • Provides an option for handling Maven repositories located at URLs using http

The --insecure-protocol option

This option is used to tell the conversion process how to handle converting Maven repositories located at insecure http URLs. Insecure Repositories Set the --insecure-protocol option. The default value is warn.

Available values are:

  • fail - Abort the build immediately upon encountering an insecure repository URL.

  • allow - Automatically sets the allowInsecureProtocol property to true for the Maven repository URL in the generated Gradle build script.

  • warn - Emits a warning about each insecure URL. Generates commented-out lines to enable each repository, as per the allow option. You will have to opt-in by editing the generated script and uncommenting each repository URL, or else the Gradle build will fail.

  • upgrade - Convert http URLs to https URLs automatically.

Compile-time dependencies

Maven automatically exposes dependencies using its implicit compile scope to the consumers of that project. This behavior is undesirable, and Gradle takes steps to help library authors reduce their API footprint using the api and implementation configurations of the java-library plugin.

Nevertheless, many Maven projects rely on this leaking behavior. As such, the init task will map compile-scoped dependencies to the api configuration in the generated Gradle build script. The dependencies of the resulting Gradle project will most closely match the exposed dependencies of the existing Maven project; however, post-conversion to Gradle we strongly encourage moving as many api dependencies to the implementation configuration as possible. This has several benefits:

  • Library maintainability - By exposing fewer transitive dependencies to consumers, library maintainers can add or remove dependencies without fear of causing compile-time breakages for consumers.

  • Consumers' dependency hygiene - Leveraging the implementation configuration in a library prevents its consumers from implicitly relying on the library’s transitive dependencies at compile-time, which is considered a bad practice.

  • Increased compile avoidance - Reducing the number of transitive dependencies leaked from a project also reduces the likelihood that an ABI change will trigger recompilation of consumers. Gradle will also spend less time indexing the dependencies for its up-to-date checks.

  • Compilation speed increase - Reducing the number of transitive dependencies leaked from a project aids the compiler process of its consumers as there are fewer libraries to classload and fewer namespaces for Gradle’s incremental compiler to track.

See the API and implementation separation and Compilation avoidance sections for more information.

java-application build type

The “java-application” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “application” plugin to produce a command-line application implemented in Java

  • Uses the “mavenCentral” dependency repository

  • Uses JUnit 4 for testing

  • Has directories in the conventional locations for source code

  • Contains a sample class and unit test, if there are no existing source or test files

Alternative test framework can be specified by supplying a --test-framework argument value. To use a different test framework, execute one of the following commands:

  • gradle init --type java-application --test-framework junit-jupiter: Uses JUnit Jupiter for testing instead of JUnit 4

  • gradle init --type java-application --test-framework spock: Uses Spock for testing instead of JUnit 4

  • gradle init --type java-application --test-framework testng: Uses TestNG for testing instead of JUnit 4

The --java-version option

When creating a java project you must set the java version. You can do that by supplying the major version of java you wish to use:

gradle init --type java-application  --java-version 11 --dsl kotlin # and other parameters

java-library build type

The “java-library” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “java” plugin to produce a library implemented in Java

  • Uses the “mavenCentral” dependency repository

  • Uses JUnit 4 for testing

  • Has directories in the conventional locations for source code

  • Contains a sample class and unit test, if there are no existing source or test files

Alternative test framework can be specified by supplying a --test-framework argument value. To use a different test framework, execute one of the following commands:

  • gradle init --type java-library --test-framework junit-jupiter: Uses JUnit Jupiter for testing instead of JUnit 4

  • gradle init --type java-library --test-framework spock: Uses Spock for testing instead of JUnit 4

  • gradle init --type java-library --test-framework testng: Uses TestNG for testing instead of JUnit 4

java-gradle-plugin build type

The “java-gradle-plugin” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “java-gradle-plugin” plugin to produce a Gradle plugin implemented in Java

  • Uses the “mavenCentral” dependency repository

  • Uses JUnit 4 and TestKit for testing

  • Has directories in the conventional locations for source code

  • Contains a sample class and unit test, if there are no existing source or test files

kotlin-application build type

The “kotlin-application” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “org.jetbrains.kotlin.jvm” and “application“ plugins to produce a command-line application implemented in Kotlin

  • Uses the “mavenCentral” dependency repository

  • Uses Kotlin 1.x

  • Uses Kotlin test library for testing

  • Has directories in the conventional locations for source code

  • Contains a sample Kotlin class and an associated Kotlin test class, if there are no existing source or test files

kotlin-library build type

The “kotlin-library” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “org.jetbrains.kotlin.jvm” plugin to produce a library implemented in Kotlin

  • Uses the “mavenCentral” dependency repository

  • Uses Kotlin 1.x

  • Uses Kotlin test library for testing

  • Has directories in the conventional locations for source code

  • Contains a sample Kotlin class and an associated Kotlin test class, if there are no existing source or test files

kotlin-gradle-plugin build type

The “kotlin-gradle-plugin” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “java-gradle-plugin” and “org.jetbrains.kotlin.jvm” plugins to produce a Gradle plugin implemented in Kotlin

  • Uses the “mavenCentral” dependency repository

  • Uses Kotlin 1.x

  • Uses Kotlin test library and TestKit for testing

  • Has directories in the conventional locations for source code

  • Contains a sample class and unit test, if there are no existing source or test files

scala-application build type

The “scala-application” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “scala” plugin to produce an application implemented in Scala

  • Uses the “mavenCentral” dependency repository

  • Uses Scala 2.13

  • Uses ScalaTest for testing

  • Has directories in the conventional locations for source code

  • Contains a sample Scala class and an associated ScalaTest test suite, if there are no existing source or test files

scala-library build type

The “scala-library” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “scala” plugin to produce a library implemented in Scala

  • Uses the “mavenCentral” dependency repository

  • Uses Scala 2.13

  • Uses ScalaTest for testing

  • Has directories in the conventional locations for source code

  • Contains a sample Scala class and an associated ScalaTest test suite, if there are no existing source or test files

groovy-library build type

The “groovy-library” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “groovy” plugin to produce a library implemented in Groovy

  • Uses the “mavenCentral” dependency repository

  • Uses Groovy 2.x

  • Uses Spock testing framework for testing

  • Has directories in the conventional locations for source code

  • Contains a sample Groovy class and an associated Spock specification, if there are no existing source or test files

groovy-application build type

The “groovy-application” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “application” and “groovy” plugins to produce a command-line application implemented in Groovy

  • Uses the “mavenCentral” dependency repository

  • Uses Groovy 2.x

  • Uses Spock testing framework for testing

  • Has directories in the conventional locations for source code

  • Contains a sample Groovy class and an associated Spock specification, if there are no existing source or test files

groovy-gradle-plugin build type

The “groovy-gradle-plugin” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “java-gradle-plugin” and “groovy” plugins to produce a Gradle plugin implemented in Groovy

  • Uses the “mavenCentral” dependency repository

  • Uses Groovy 2.x

  • Uses Spock testing framework and TestKit for testing

  • Has directories in the conventional locations for source code

  • Contains a sample class and unit test, if there are no existing source or test files

cpp-application build type

The “cpp-application” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “cpp-application” plugin to produce a command-line application implemented in C++

  • Uses the “cpp-unit-test” plugin to build and run simple unit tests

  • Has directories in the conventional locations for source code

  • Contains a sample C++ class, a private header file and an associated test class, if there are no existing source or test files

cpp-library build type

The “cpp-library” build type is not inferable. It must be explicitly specified.

It has the following features:

  • Uses the “cpp-library” plugin to produce a C++ library

  • Uses the “cpp-unit-test” plugin to build and run simple unit tests

  • Has directories in the conventional locations for source code

  • Contains a sample C++ class, a public header file and an associated test class, if there are no existing source or test files

basic build type

The “basic” build type is useful for creating a new Gradle build. It creates sample settings and build files, with comments and links to help get started.

This type is used when no type was explicitly specified, and no type could be inferred.