Ant was the first among “modern” build tools. In many aspects it is similar to Make. It was released in 2000 and in a short period of time became the most popular build tool for Java projects. It has very low learning curve thus allowing anyone to start using it without any special preparation. It is based on procedural programming idea.
After its initial release, it was improved with the ability to accept plug-ins.
Major drawback was XML as the format to write build scripts. XML, being hierarchical in nature, is not a good fit for procedural programming approach Ant uses. Another problem with Ant is that its XML tends to become unmanageably big when used with all but very small projects.
Later on, as dependency management over the network became a must, Ant adopted Apache Ivy.
Main benefit of Ant is its control of the build process.
Maven was released in 2004. Its goal was to improve upon some of the problems developers were facing when using Ant.
Maven continues using XML as the format to write build specification. However, structure is diametrically different. While Ant requires developers to write all the commands that lead to the successful execution of some task, Maven relies on conventions and provides the available targets (goals) that can be invoked. As the additional, and probably most important addition, Maven introduced the ability to download dependencies over the network (later on adopted by Ant through Ivy). That in itself revolutionized the way we deliver software.
However, Maven has its own problems. Dependencies management does not handle well conflicts between different versions of the same library (something Ivy is much better at). XML as the build configuration format is strictly structured and highly standardized. Customization of targets (goals) is hard. Since Maven is focused mostly on dependency management, complex, customized build scripts are actually harder to write in Maven than in Ant.
Maven configuration written in XML continuous being big and cumbersome. On bigger projects it can have hundreds of lines of code without actually doing anything “extraordinary”.
Main benefit from Maven is its life-cycle. As long as the project is based on certain standards, with Maven one can pass through the whole life cycle with relative ease. This comes at a cost of flexibility.
In the mean time the interest for DSLs (Domain Specific Languages) continued increasing. The idea is to have languages designed to solve problems belonging to a specific domain. In case of builds, one of the results of applying DSL is Gradle.
Gradle combines good parts of both tools and builds on top of them with DSL and other improvements. It has Ant’s power and flexibility with Maven’s life-cycle and ease of use. The end result is a tool that was released in 2012 and gained a lot of attention in a short period of time. For example, Google adopted Gradle as the default build tool for the Android OS.
Gradle does not use XML. Instead, it had its own DSL based on Groovy (one of JVM languages). As a result, Gradle build scripts tend to be much shorter and clearer than those written for Ant or Maven. The amount of boilerplate code is much smaller with Gradle since its DSL is designed to solve a specific problem: move software through its life cycle, from compilation through static analysis and testing until packaging and deployment.
It is using Apache Ivy for JAR dependencies.
Gradle effort can be summed as “convention is good and so is flexibility”.
We’ll create build scripts that will compile, perform static analysis, run unit tests and, finally, create JAR files. We’ll do those operations in all three frameworks (Ant, Maven and Gradle) and compare the syntax. By comparing the code for each task we’ll be able to get a better understanding of the differences and make an informed decision regarding the choice of the build tool.
First things first. If you’ll do the examples from this article by yourself, you’ll need Ant, Ivy, Maven and Gradle installed. Please follow installation instructions provided by makers of those tools. You can choose not to run examples by yourself and skip the installation altogether. Code snippets should be enough to give you the basic idea of how each of the tools work.
Code repository https://github.com/vfarcic/JavaBuildTools contains the java code (two simple classes with corresponding tests), checkstyle configuration and Ant, Ivy, Maven and Gradle configuration files.
Let’s start with Ant and Ivy.