When you create a java project (for a library or an application or a web site), while you could just rely on your IDE to build things for you, in most cases you really need a build script. For a build script, you basically have 3 choices: Ant, Maven or Gradle.
Now that I’ve used all three of these tools, thought I’d share some thoughts about how to choose between them. This is not an article about how to migrate from one of them to another – that’s usually not worth the pain if your build is complicated, and it’s fairly trivial if your build is very simple.
In the context of a new project, let’s take a look at each of the choices:
Ant is the old-school tool. Your build script is basically a list of configured commands in XML, organized as a set of interdependent tasks. It’s easy to learn, and relatively easy to debug. It’s pretty easy to extend with custom tags implemented in Java (I’ve created one myself). Ant does not naturally include dependency management (loading external jar files), bit that can be added with Apache Ivy.
- easy to learn
- easy to understand
- excellent integration in IDE’s
- lots of examples and help online
- Procedural (build scripts can get very complicated)
- For dependency management, Ivy is less intuitive and requires extra configuration and tooling
Maven is the opinionated tool which forces a project structure and build life cycle on you, and it’s also the tool that introduced built-in dependency management and a central repository for dependencies. Like Ant, it’s based on XML. Some people hate Maven for making them do things Maven’s way, but the benefit is simplicity. Unlike with Ant and Gradle scripts, two Maven scripts which do roughly the same thing are very similar. I have not tried to extend its functionality, but Maven has a plugin architecture, and a lot of useful plugins are available. Maven is also well-integrated in a number of popular tools.
- generally very little thought or debugging required to get a typical build working
- strong integration with various CI and IDE tools
- simple dependency management
- lots of examples and explanations online
- Lots of pain if you don’t organize your project the Maven way
A relative newcomer, Gradle offers an elegant groovy-based DSL to run your build. Like Maven, Gradle has built-in dependency-management and makes some assumptions about project structure, but like Ant its execution is based on tasks. Unlike both Ant and Maven, Gradle has an elegant syntax which allows you to essentially write your build code in Groovy. Unlike Maven, the assumptions about project structure are conventions rather than rules. I have to say, though, that I recently encountered an official Gradle plugin which takes some of those assumptions as hard rules, and I had to abandon the plugin and use another tool. Hopefully this situation will improve over time. One thing I really like about Gradle is its dependency management syntax, which allows much simpler find-replace for version upgrades than Maven’s XML tags. The library name and version are all together on one line.
- Elegance (i.e. lack of XML tags)
- simple dependency management
- Immature tooling and immature integration with popular tools (CI, IDE)
- limited examples and help online
- steep learning curve (especially for Groovy noobs)
- inflexible plugins.
All three of these tools are good tools which can get the job done if you know what you’re doing. Personally, for a new Java project, I’d chose Maven for basic building of jar and war files. It’s what I did choose, even for my open-source Ant plugin. I Ant also, for non-build tasks (mass file copying with text replacement, for example) and tasks around the builds (for example, to update versions of dependency libraries and to rebuild the delegate interfaces using interface-it ant). Gradle is a very elegant and promising tool which will surely resolve some of its weak points over time. If you’re comfortable with groovy, it might be the right choice for you, but only if you stick to their recommended multi-project structure and don’t lean too heavily on your IDE.