Procedurally generating a 2D galaxy

I am fairly new to java and I am working on a project that will simulate a galaxy of 2 dimensional solar systems containing planets stars etc.

I have been doing some research but I cannot find a clear answer on how to generate such a random world. I have also had a go at it myself.

So my question is how do I go about procedurally generating such a world that will follow the rules of an average solar system in 2 dimensional space with java?

I am also quite open to ideas such as using generated seeds etc. If you believe that would be a better option.