Apache Ant™ is a Java library and command-line tool whose mission is to drive processes described in build files as targets and extension points dependent upon each other. The main known usage of Ant is the build of Java applications. Ant supplies a number of built-in tasks allowing to compile, assemble, test and run Java applications. Ant can also be used effectively to build non Java applications, for instance C or C++ applications. More generally, Ant can be used to pilot any type of process which can be described in terms of targets and tasks.
Ant is written in Java and thus requires Java 8 or a later runtime environment to be installed. If you want to build a Java project you will need a Java Development Kit rather than just a Java Runtime Environment.