How to sort HashSet in Java
Last Updated :
11 Jul, 2025
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Given a HashSet in Java, the task is to sort this HashSet.
Examples:
Java
Java
Input: HashSet: [Geeks, For, ForGeeks, GeeksforGeeks] Output: [For, ForGeeks, Geeks, GeeksforGeeks] Input: HashSet: [2, 5, 3, 1, 4] Output: [1, 2, 3, 4, 5]The HashSet class implements the Set interface, backed by a hash table which is actually a HashMap instance. No guarantee is made as to the iteration order of the set which means that the class does not guarantee the constant order of elements over time. It means that HashSet does not maintains the order of its elements. Hence sorting of HashSet is not possible. However, the elements of the HashSet can be sorted indirectly by converting into List or TreeSet, but this will keep the elements in the target type instead of HashSet type. Below is the implementation of the above approach: Program 1: By Converting HashSet to List.
// Java program to sort a HashSet
import java.util.*;
public class GFG {
public static void main(String args[])
{
// Creating a HashSet
HashSet<String> set = new HashSet<String>();
// Adding elements into HashSet using add()
set.add("geeks");
set.add("practice");
set.add("contribute");
set.add("ide");
System.out.println("Original HashSet: "
+ set);
// Sorting HashSet using List
List<String> list = new ArrayList<String>(set);
Collections.sort(list);
// Print the sorted elements of the HashSet
System.out.println("HashSet elements "
+ "in sorted order "
+ "using List: "
+ list);
}
}
// Java program to sort a HashSetimport java.util.*;public class GFG { public static void main(String args[]) { // Creating a HashSet HashSet<String> set = new HashSet<String>(); // Adding elements into HashSet using add() set.add("geeks"); set.add("practice"); set.add("contribute"); set.add("ide"); System.out.println("Original HashSet: " + set); // Sorting HashSet using List List<String> list = new ArrayList<String>(set); Collections.sort(list); // Print the sorted elements of the HashSet System.out.println("HashSet elements " + "in sorted order " + "using List: " + list); }}
Output:
Program 2: By Converting HashSet to TreeSet.
Original HashSet: [practice, geeks, contribute, ide] HashSet elements in sorted order using List: [contribute, geeks, ide, practice]
// Java program to sort a HashSet
import java.util.*;
public class GFG {
public static void main(String args[])
{
// Creating a HashSet
HashSet<String> set = new HashSet<String>();
// Adding elements into HashSet using add()
set.add("geeks");
set.add("practice");
set.add("contribute");
set.add("ide");
System.out.println("Original HashSet: "
+ set);
// Sorting HashSet using TreeSet
TreeSet<String> treeSet = new TreeSet<String>(set);
// Print the sorted elements of the HashSet
System.out.println("HashSet elements "
+ "in sorted order "
+ "using TreeSet: "
+ treeSet);
}
}
// Java program to sort a HashSetimport java.util.*;public class GFG { public static void main(String args[]) { // Creating a HashSet HashSet<String> set = new HashSet<String>(); // Adding elements into HashSet using add() set.add("geeks"); set.add("practice"); set.add("contribute"); set.add("ide"); System.out.println("Original HashSet: " + set); // Sorting HashSet using TreeSet TreeSet<String> treeSet = new TreeSet<String>(set); // Print the sorted elements of the HashSet System.out.println("HashSet elements " + "in sorted order " + "using TreeSet: " + treeSet); }}
Output:
Original HashSet: [practice, geeks, contribute, ide] HashSet elements in sorted order using TreeSet: [contribute, geeks, ide, practice]
