Last 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 binarySearch(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 min = start + (end - start)/2;

            if (nums[min] == target) {
                start = mid;
            }
            else if(nums[min] < target){
                start = mid;
            }else {
                end = mid;
            }
        }

        if (nums[end] == target) {
            return end;
        }
        if (nums[start] == target) {
            return start;
        }

        return -1;
    }
}