Two of the build systems that are very commonly used in the Java landscape are Apache Maven and Gradle. When you are working on an enterprise Java application, it's very likely that you'll have to deal with one of these two options. In this book so far, we've been working with the command line to get the compiler and runtime to execute. However, that's rarely a reasonable thing to do in a complex project. So, what does it take to use such a build system in a Java 9 modular application?