Sorting HashSet In Ascending & Descending order + Java 8

 Hi All,

Greetings on the day!

Today we will see how we can sort HashSet in both ascending & descending order, also we will learn how we can sort HashSet using java 8.

So let's start.

We can sort HashSet using TreeSet & ArrayList. TreeSet will automatically order data in ascending order.

 If we want to use ArrayList we need to follow the below 3 steps.

• Convert Set to ArrayList
• Sort List
• Convert list to set

So let's see the example of that.

package com.demo; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.HashSet; import java.util.LinkedHashSet; import java.util.Set; import java.util.TreeSet; import java.util.stream.Collectors; public class SortingHashMap { public static void main(String[] args) { Set<String> strings = new HashSet<>(); strings.add("Rajesh"); strings.add("Pratik"); strings.add("Ankit"); strings.add("Bhavesh"); TreeSet<String> sortedSet = new TreeSet<>(strings); System.out.println("Sorted in ascending order using TreeSet " + sortedSet); // Convert Set to ArrayList ArrayList<String> arrayList = new ArrayList<>(sortedSet); // Sort List in ascending order Collections.sort(arrayList); // Convert list to set HashSet<String> sortedStrings = new LinkedHashSet<>(arrayList); System.out.println("Sorted in ascending order using ArrayList " + sortedStrings); // Sorting list in descending order Collections.sort(arrayList, Collections.reverseOrder()); HashSet<String> sortedStringsInDesc = new LinkedHashSet<>(arrayList); System.out.println("Sorted in descending order using ArrayList " + sortedStringsInDesc); } }

O/P

Sorted in ascending order using TreeSet [Ankit, Bhavesh, Pratik, Rajesh]

Sorted in ascending order using ArrayList [Ankit, Bhavesh, Pratik, Rajesh]

Sorted in descending order using ArrayList [Rajesh, Pratik, Bhavesh, Ankit] 

Now let's see how to sort HashSet in ascending & descending order using java 8 streams.

package com.demo; import java.util.Collections; import java.util.HashSet; import java.util.Set; import java.util.stream.Collectors; public class SortingHashMap { public static void main(String[] args) { Set<String> strings = new HashSet<>(); strings.add("Rajesh"); strings.add("Pratik"); strings.add("Ankit"); strings.add("Bhavesh"); //Sorting in ascending order System.out.println("In A" + "scending Order"); strings.stream().sorted().collect(Collectors.toList()).forEach(System.out::println); //Sorting in descending order System.out.println("In Descending Order"); strings.stream().sorted(Collections.reverseOrder()). collect(Collectors.toList()).forEach(System.out::println); } }

O/P

In Ascending Order Ankit Bhavesh Pratik Rajesh In Descending Order Rajesh Pratik Bhavesh Ankit

Hope you have a good learning experience. If you have any questions let me know.

You can refer to the related post.

Java Interview Programs - Count No Of Occurrences Of Element In List + Find Duplicate Elements In List + Java 8

Sorting HashMap By Key And Value + Java 8

Sorting Array List In Ascending & Descending Order + Java 8 + Sorting Array List Of Custom Object

Comparator and Comparable In Java + Difference Between Comparator and Comparable + Java 8

Java 8 Stream - Intermediate Operations With Examples

Java 8 Stream - Terminal Operations With Examples

For Spring visit Spring Tutorial

Thanks

Happy Learning!