I am creating a simple reporting program using java and iReport (from jasper), which is supposed to create a report in pdf showing PCs with their IP address, their location,
Interesting. I think you'd better use the List, and then define getName() on the Project class. Then in the subreport define a variable "name". It will work this way, and it will allow you to add easily additional information, like project duration, team-lead, etc.