Evolving Gradle Build from Ant Build: Importing Ant Build File

Changing the build system on a large project can be difficult and a lot of work. Fortunately for those migrating Ant builds to Gradle builds, Gradle provides particularly convenient mechanisms to facilitate this migration. Because Gradle is built on Groovy and Groovy includes built-in Ant support via AntBuilder, Gradle builds can use AntBuilder to call Ant tasks and run Ant targets. However, Gradle provides an even easier mechanism for referencing existing Ant targets from a Gradle build with Gradle’s support for importing an Ant build via DefaultAntBuilder and that is the subject of this post.

Being able to call existing Ant targets from a new Gradle build is advantageous because it allows the migration to take place over time. One can start using Gradle almost immediately with all the real work delegated to the existing Ant build. Then, as time and priorities allow, different Ant tasks can be replaced with Gradle tasks.

To demonstrate how easy it is to import an Ant build in a Gradle build, I first provide the code listing for a simplified Ant build.

Ant Build File: build.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="JavaArrays" default="all" basedir=".">
   <description>Java Array Utility Functions</description>

   <property name="javac.debug" value="true" />
   <property name="src.dir" value="src" />
   <property name="dist.dir" value="dist" />
   <property name="classes.dir" value="classes" />
   <property name="javadoc.dir" value="${dist.dir}/javadoc" />

   <property name="jar.name" value="javaArrays.jar" />
   <property name="jar.filesonly" value="true" />

   <path id="classpath">

   <target name="-init">
      <mkdir dir="${classes.dir}" />
      <mkdir dir="${dist.dir}" />

   <target name="compile"
           description="Compile the Java code."
      <javac srcdir="${src.dir}"
             includeantruntime="false" />

   <target name="jar"
           description="Package compiled classes into JAR file"
      <jar destfile="${dist.dir}/${jar.name}"

   <target name="all"
           description="Compile Java source, assemble JAR, and generate documentation"
           depends="jar, javadoc" />

   <target name="javadoc" description="Generate Javadoc-based documentation">
      <mkdir dir="${javadoc.dir}" />
      <javadoc doctitle="Examples of Java Array Utility Functions"
               author="Dustin" />

   <target name="clean" description="Remove generated artifacts.">
      <delete dir="${classes.dir}" />
      <delete dir="${dist.dir}" />


The above Ant build file has some fairly typical targets with names like “compile”, “jar”, “javadoc”, and “clean”. All of this functionality can be imported into a Gradle build file. The next code listing is the complete Gradle build file that does this.

Gradle build.gradle that imports Ant build.xml

ant.importBuild 'build.xml'

The one-line Gradle build file shown above imports the Ant build file shown earlier. The effects of this can be easily seen in the following screen snapshots. The initial screen snapshot shows that the single line Gradle build file makes the “arrays” project available to the Gradle build as well as “other tasks” of “all” and “clean” with the descriptions associated with those Ant targets.


One can use gradle tasks --all to see all Ant targets, including the dependent targets such as “compile”, “jar”, and “javadoc”. This is demonstrated in the next screen snapshot.


The next screen snapshot demonstrates running the default “all” target in the Ant build from the Gradle build.


As the build listings and images have demonstrated, importing an existing Ant build in a Gradle build is a straightforward process.

Related Whitepaper:

Functional Programming in Java: Harnessing the Power of Java 8 Lambda Expressions

Get ready to program in a whole new way!

Functional Programming in Java will help you quickly get on top of the new, essential Java 8 language features and the functional style that will change and improve your code. This short, targeted book will help you make the paradigm shift from the old imperative way to a less error-prone, more elegant, and concise coding style that’s also a breeze to parallelize. You’ll explore the syntax and semantics of lambda expressions, method and constructor references, and functional interfaces. You’ll design and write applications better using the new standards in Java 8 and the JDK.

Get it Now!  

Leave a Reply

six × 8 =

Java Code Geeks and all content copyright © 2010-2014, Exelixis Media Ltd | Terms of Use
All trademarks and registered trademarks appearing on Java Code Geeks are the property of their respective owners.
Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries.
Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation.

Sign up for our Newsletter

15,153 insiders are already enjoying weekly updates and complimentary whitepapers! Join them now to gain exclusive access to the latest news in the Java world, as well as insights about Android, Scala, Groovy and other related technologies.

As an extra bonus, by joining you will get our brand new e-books, published by Java Code Geeks and their JCG partners for your reading pleasure! Enter your info and stay on top of things,

  • Fresh trends
  • Cases and examples
  • Research and insights
  • Two complimentary e-books