twoSum Algorithm : How to improve this?

Question

I felt like doing an algorithm and found this problem on leetcode

Given an array of integers, find two numbers such that they add up to a specific target num

Answer 1

Using HashMap this is also a solution if complexity for search in HashMap will in order of O(logn) then in worst case the complexity will be O(nlogn)

    public int[] twoSum(int[] nums, int target) {
        
        int [] resultIndex = null;
        
        HashMap map = new HashMap();
        
        for(int i=0;i