duplicates in list java code example

Example 1: java remove duplicates

import java.util.*;

public class RemoveDuplicatesFromArrayList {

    public static void main(String[] args) {
        List<Integer> numbers = Arrays.asList(1,2,2,2,3,5);

        System.out.println(numbers);

        Set<Integer> hashSet = new LinkedHashSet(numbers);
        ArrayList<Integer> removedDuplicates = new ArrayList(hashSet);

        System.out.println(removedDuplicates);
    }
}

Example 2: java find duplicate element in list

public static Set<String> findDuplicates(List<String> listContainingDuplicates) {
 
		final Set<String> setToReturn = new HashSet<String>();
		final Set<String> set1 = new HashSet<String>();
 
		for (String yourInt : listContainingDuplicates) {
			if (!set1.add(yourInt)) {
				setToReturn.add(yourInt);
			}
		}
		return setToReturn;
	}