Below is a Java program to remove duplicates from an ArrayList:

import java.util.ArrayList;

import java.util.HashSet;

import java.util.List;

public class RemoveDuplicates {

public static void main(String[] args) {

// Create an ArrayList with duplicates

List<Integer> numbersWithDuplicates = new ArrayList<>();








System.out.println("ArrayList with duplicates: " + numbersWithDuplicates);

// Remove duplicates

List<Integer> numbersWithoutDuplicates = removeDuplicates(numbersWithDuplicates);

// Print ArrayList after removing duplicates

System.out.println("ArrayList after removing duplicates: " + numbersWithoutDuplicates);


public static <T> List<T> removeDuplicates(List<T> list) {

// Create a HashSet to store unique elements

HashSet<T> set = new HashSet<>();

// Create a new ArrayList to store elements without duplicates

List<T> newList = new ArrayList<>();

// Iterate over the original list

for (T element : list) {

// If element is not already in the HashSet, add it to the new list and set

if (set.add(element)) {




return newList;




- The `removeDuplicates()` method takes an ArrayList as input and returns a new ArrayList with duplicates removed.

- It uses a HashSet to store unique elements encountered in the ArrayList.

- Elements are iterated over one by one, and if they are not already present in the HashSet, they are added to both the HashSet and the new ArrayList.

- This ensures that only unique elements are added to the new ArrayList.

- Finally, the new ArrayList without duplicates is returned.