TreeSet in java
// java treeset example import java.util.Iterator; import java.util.TreeSet; public class TreeSetExamples { public static void main(String[] args) { TreeSet<String> ts = new TreeSet<String>(); ts.add("red"); ts.add("blue"); ts.add("green"); ts.add("red"); Iterator<String> iterate = ts.iterator(); while(iterate.hasNext()) { System.out.println(iterate.next()); } } }