• Java Development Kit: http://www.oracle.com/technetwork/java/javase/downloads/index-jsp-138363.html#javasejdk

• Gradle: https://gradle.org/downloads/

After JDK installation make sure that the variable JAVA_HOME exists in your system.

You can read another installation guides, if you use target IDEs:

• IntelliJ IDEA
• Eclipse
• NetBeans

Then see getting started page.