Find the odd one from a non empty integer array in java

Given a non-empty array of integers, every element appears twice except for one. Find that single one.

class Cfed{

public int singleNumber(int[] nums) {

int length = nums.length;

for (int i = 0; i < length - 1; i++) {

if (nums[i] > nums[i + 1]) {

int temp = nums[i];

nums[i] = nums[i + 1];

nums[i + 1] = temp;

i = -1;

}

}

int i = 0;

int ans = nums[length-1];

while (i+1 < length) {

if(nums[i]!=nums[i+1]) {

ans =  nums[i];

break;

}

i+=2;

}

return ans;

}

public static void main(String[] args) {

Cfed s = new Cfed();

int[] nums = { 4,1,2,1,2 }; 

System.out.println(s.singleNumber(nums));

}

}