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

My solution to this problem would be,

public int[] twoSums(int[] unsortedNum, int target) {
        int[] nums = Arrays.copyOf(unsortedNum, unsortedNum.length);
        Arrays.sort(nums);
        boolean isResultFound = false;
        int start = 0;
        int end = nums.length-1;
        while(!(start > end)) {
            if(nums[start]+nums[end] > target){
                end--;
            } else if (nums[start]+nums[end] < target){
                start++;
            } else if(nums[start] + nums[end] == target){
                isResultFound = true;
                break;
            }
        }
        if(isResultFound){
            int s = -1;
            int e = -1;
            for(int i = 0; i< unsortedNum.length; i++){
                if(s != -1 && e != -1){
                    break;
                }
                if(s == -1 && unsortedNum[i] == nums[start]){
                    s = i;
                } else if(e == -1 && unsortedNum[i] == nums[end]) {
                    e = i;
                }
            }
            return new int[] {s,e};
        }
        // for element not found
        return new int[]{-1,-1};
    }

In the end, if you get -1, -1 as the index then you can say that elements not found which could sum to the target element.