Java Set Operations

As you know, for a while I’ve been playing with Solr. Basically implementing federated search framework to aggregate different ERP, CRM, PLM space data sources.
This post is not about federated search but I keep using bunch of set operations to compare the search results, comparing the unique doc id etc.

public class SetOperations {
 public static  Set union(Set setA, Set setB) {
     Set tmp = new TreeSet(setA);
     tmp.addAll(setB);
     return tmp;
   }

   public static  Set intersection(Set setA, Set setB) {
     Set tmp = new TreeSet();
     for (T x : setA)
       if (setB.contains(x))
         tmp.add(x);
     return tmp;
   }

   public static  Set difference(Set setA, Set setB) {
     Set tmp = new TreeSet(setA);
     tmp.removeAll(setB);
     return tmp;
   }
   
   public static void main(String[] args) {
         
        SortedSet s1=  new TreeSet();
        s1.add("one");
        s1.add("two");

        SortedSet s2=  new TreeSet();
        s2.add("two");
        s2.add("three");
        s2.add("four");
         
        SortedSet result = (SortedSet) union(s1,s2);
        
        Iterator it = result.iterator();
        System.out.print("union result  -->");
         while (it.hasNext()) {
             String value = it.next();
             System.out.print(value+", ");
         }
         System.out.println("\n");
         
         result = (SortedSet) intersection(s1,s2);
         
      it = result.iterator();
      System.out.print("intersection result-->");
      while (it.hasNext()) {
              String value = it.next();
              System.out.print(value+ ", ");
      }
      System.out.println("\n");

         result = (SortedSet) difference(s1,s2);
         
      it = result.iterator();
      System.out.print("difference result-->");
      while (it.hasNext()) {
              String value = it.next();
              System.out.print(value+", ");
      }
      System.out.println("\n");
      
         /*
         SortedSet i1=  new TreeSet();
         i1.add(new Integer("1"));
         
         SortedSet i2=  new TreeSet();
         i2.add(new Integer("2"));
         
         SortedSet iresult = (SortedSet) union(i1,i2);
         
         Iterator iit = iresult.iterator();
         System.out.println("Integer union result");
          while (iit.hasNext()) {
           Integer value = iit.next();
              System.out.println(value+",");
          }
         */
   }
   
}