Add Build file to project
A build file should be added to a project to enable running the build, filtering targets, or defining properties. One project can have several build files. The build files are grouped in the Ant tool window by names, specified in the root element of each build file, for example
In the Project tool window, right-click the generated build file and select Add as Ant Build File to open it in the Ant tool window.
In the Ant Build tool window, click .
In the Select Path dialog, navigate to the desired build.xml file, and click OK.
A build file should have at least a root element to be added to the Ant Build tool window.