Jakarta Commons IO uses Maven as build system. Please install Maven prior to attempting a build of IO.
Change into IO's root directory and run "maven jar" to build the JAR file. After a successful build you will find it in the "target" subdirectory.
To build the Javadocs, run "maven javadoc". The result will be in "target/docs/apidocs".
To build the full website, run "maven site". The result will be in "target/docs".