Java Programming

I'm working on this project and I need some help. What I've got is an ArrayList of objects each of which consists of (name, x coordinate, y coordinate). What I need to do is generate a combination of all possible combinations of objects and print their name. The method in which I am trying to write takes a subset size. For example say I've got an ArrayList of the following:
[a,b,c,d,e]
The method will receive a subset size that is specified by the user, we'll go with 3 for this example. I need to print the following:
a,b,c
a,b,d
a,b,e
a,c,d
a,c,e
a,d,e
b,c,d
b,c,e
b,d,e

I figure that recursion is a must because if the subset size is set for anything other than what I intend my for statements would not work. I just cannot figure out how I would do this. I've worked with recursion before but am stumped. Any help would be greatly appreciated.

Thank you!