Given an array of integers, every element appears twice except for one. Find that single one.

public class Solution {
    public int singleNumber(int[] nums) {
        if(nums.length==1){  
            return nums[0];  
        }else if(nums.length%2 == 0){  
            return 0;  
        }else{  
            Arrays.sort(nums);  
            int n = nums.length-1;  
            for(int i=0;i<n;i+=2){  
                if(nums[i] != nums[i+1]){  
                    return nums[i];  
                }  
            }  
            return nums[n];  
        }  
    }
}