Design question: Java Class with single method ok?

Question

I need the following functionality

Given two sorted lists, merge them

I have this skeleton Java code:

public class MergeLists{
   public List merge(List l1, List l2){
      List l3;
      // merge l1, l2 in to l3
      return l3;
   }

   public static void main(){
      // populate list1 and list2
      MergeLists ml = new MergeLists();
      List l3 = ml.merge(l1,l2);
   }
}

Is this single method class the right approach? I feel like the almost-empty class is staring at me to say that this is bad design. I initially had List L3 as private member of MergeLists but then I thought, merge(l1,l2) can be called multiple times with the same object, which required l3 to be local to merge(l1,l2). I read that using static method is even worse for code re-usability. Please advise. Thank you.

Answer 1

You can do this, but I think you want the merge method to be static. This will make sure that you don't have to instantiate it before calling the method. You can just do this:

List l3 = MergeLists.merge(l1,l2);

Additionally, if this is the only method and it's static, you can make the class abstract which means it cannot be instantiated.