Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

public class Solution {
    public int reverse(int x) {
        int ret = 0;
        int i = 10;
        int x_cpy = x;
        ArrayList<Integer> array = new ArrayList<Integer>();
        while (x!=0) {
            int di = x%10;
            array.add(Math.abs(di));
            x /= 10;
        }
        int temp= (int) Math.pow(10,(array.size()-1));
        for(i=0;i<array.size();i++){
            ret += array.get(i)*temp;
            temp /= 10;
        }
        if (x_cpy<0) {
            return 0-ret;
        }
        return ret;
    }
}