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Categories / Java Tutorial / Collections
 

To add a single element

The element to add must implement the Comparable interface or the TreeSet constructor must have been passed a Comparator. If both of these are not true then a ClassCastException will be thrown. import java.util.*; import java.util.Collections; import java.util.Set; import java.util.TreeSet; public class MainClass {   public static void main(String args[]) throws Exception {     String elements[] = { "A", "C", "D", "G", "F" };     Set set = new TreeSet(Collections.reverseOrder());     for (int i = 0, n = elements.length; i < n; i++) {       set.add(elements[i]);     }     System.out.println(set);   } } [G, F, D, C, A]