// This is a java program to display the use of the java.util.TreeSet class import java.util.TreeSet; public class TreeSetExample { public static void main(String[] args) { System.out.println("TreeSet is like HashSet but it sorts the elements in ascending order."); TreeSet treeSet = new TreeSet(); // Instance using Default Constructor treeSet.add("Simple"); // adding elements using the .add() method treeSet.add("TreeSet"); treeSet.add("TreeSet"); System.out.println(treeSet); // output will be a set of strings in the instance. // TreeSet is implemented from the SortedSet interface and will omit duplicates TreeSet duplicateEntryTreeSet = new TreeSet(); duplicateEntryTreeSet.add(300); duplicateEntryTreeSet.add(102); duplicateEntryTreeSet.add(102); // Duplicate value will not be stored System.out.println(duplicateEntryTreeSet); // Output will be [102, 300] // Objects stored in TreeSet should be homogeneous // and comparable otherwise the program will throw an exception TreeSet builderSet = new TreeSet(); builderSet.add(new StringBuilder("T")); // Will result in java.lang.ClassCastException builderSet.add(new StringBuilder("M")); builderSet.add(new StringBuilder("I")); } }