how to match elements from one set to elements in another set using firebase : I recently started to learn android and I came across a problem. I want to create a code for firebase ( the database i am using to store values) such that the contents from one set are matched to elements in another set. The scenario is as follows - there is a student who wants to learn or is interested in learning a new skill(c/c++,drawing,music etc.) if he were to update them in their profile he should get suggestions as names of other users registered in the application who have already listed their skill set. It is much like how facebook suggests common friends but here the basis for suggestion is what skills the user has and what he wants to learn.