Sets can be generic. : generics « Utility Classes « SCJP

1. SCJP
2. Utility Classes
3. generics

import java.util.HashSet;
import java.util.Set;
import java.util.TreeSet;

public class MainClass {
  public static void main(String[] argv) {
    Set<String> stringSet = new HashSet<String>();
    stringSet.add("a");
    stringSet.add("b");
    stringSet = new TreeSet<String>();

  }
}