Add num1 elements in set1, and while adding num2 elements, check if they exist in num1 and add only the intersection.

public class Solution { 
	public int[] intersection(int[] nums1, int[] nums2) { 
		// Use a set to store elements from nums1 
		Set<Integer> set1 = new HashSet<>(); 
		for (int num : nums1) { 
			set1.add(num); 
		} 
		// Use another set to store the intersection 
		Set<Integer> result = new HashSet<>(); 
		for (int num : nums2) { 
			if (set1.contains(num)) { 
				result.add(num); // Add only if it exists in nums1 
			} 
		} 
			// Convert the result set to an array return  
			result.stream().mapToInt(Integer::intValue).toArray();   
		} 
	}