Find Peak Element BS LeetCode

class Solution {
    public int findPeakElement(int[] nums) {
        if(nums.length==1){
            return 0;
        }

        int low = 0, high = nums.length-1;

        while(low<=high){
            int mid = (low+high)/2;
            int checkVal = check(nums, mid);

            if(checkVal==0){
                return mid;
            } else if (checkVal ==1){
                low=mid+1;
            } else{
                high=mid-1;
            }
        }
        return -1;
    }

    private int check(int[] nums, int idx){
        int n= nums.length;
        int lowerIdx = idx-1;
        int higherIdx = idx+1;

        if(lowerIdx == -1){
            return (nums[idx]>nums[higherIdx]) ? 0 : 1;
        } 
        if(higherIdx == n){
            return (nums[idx]>nums[lowerIdx]) ? 0 : -1;
        }
        if(nums[idx]<nums[lowerIdx]){
            return -1;
        }
        if(nums[idx]<nums[higherIdx]){
            return 1;
        }

        return 0;
    }
}