Missing Number 位运算

public int missingNumber(int[] nums) {
        if(nums.length == 0 || nums == null)
            return 0;
        int missing = 0;
        for(int i = 0; i <= nums.length; i++)
            missing ^= i;
        for(int i = 0 ; i < nums.length; i++) {
            missing ^= nums[i];
        }
        return missing;
    }