find duplicate elements in array in java?

There are multiple way to find duplicate elements in array in java.

Using nested for loop :-

First we create nested for loop and iterate the elements.
Now from if condition we check first elements is equals to next elements.
If elements is equals, then print data s[j].

Using stream() method :-

First convert String Arrays to list using Arrays.asList method
Now get the Stream data from List using arrayList.stream() method
Create String type hashset object.
By filter we add duplicate data from hashset.
Now collect data into list and print from forEach method.

				
					import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;

public class DuplicateArrayElements {
	public static void main(String[] args) {
		String[] s = { "dell", "hp", "sony", "dell", "ibm", "hp", "microsoft" };

		System.out.println("duplicate String from for loop is :- ");
		for (int i = 0; i < s.length - 1; i++) {
			for (int j = i + 1; j < s.length; j++) {
				if ((s[i].equals(s[j])) && (i != j)) {
					System.out.println(s[j]);
				}
			}
		}

		System.out.println("from stream and filter method :-");
		Set<String> h = new HashSet<String>();
		Arrays.asList(s).stream().filter(r -> !h.add(r)).collect(Collectors.toList()).forEach(System.out::println);
	}
}

Output :-
duplicate String from for loop is :-
dell
hp
from stream and filter method :-
dell
hp