First Position Of Target

public class Solution {
    /**
     * @param nums: The integer array.
     * @param target: Target to find.
     * @return: The first position of target. Position starts from 0.
     */
    public int binarySea rch(int[] nums, int target) {
        // write your code here
        
        if(nums == null || nums.length == 0){
            return -1;
        }
        
        int start = 0, end = nums.length -1;
        
        while(start + 1 < end){
            int mid = start + (end - start)/2;
            
            if(nums[mid] == target){
                end = mid;
            }
            else if(nums[mid] < target){
                start = mid;
            }else{
                end = mid;
            }
        }
        
        if(nums[start] == target) {
            return start;
        }
        if(nums[end] == target){
            return end;
        }
        
        return -1;
    }
}