What build automation systems have you been familiar with or used in practice?

The most commonly used build automation systems in Java projects are:

• Maven — a declarative build system that uses the pom.xml file to manage dependencies and the project lifecycle.
• Gradle — a more flexible and modern system that uses scripts written in Groovy or Kotlin DSL.
• Ant — an older tool based on XML scripts, often used in inherited projects.

Example of using Maven to build a project:

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example</groupId>
  <artifactId>my-app</artifactId>
  <version>1.0-SNAPSHOT</version>
  <dependencies>
    <!-- dependencies -->
  </dependencies>
</project>

Gradle allows writing scripts in Kotlin DSL:

tasks.register("hello") {
    doLast {
        println("Hello, Gradle!")
    }
}

The choice of system depends on the project requirements and team preferences.