1.Get length of this Integer.

2.complementation and division

class Solution {

public int reverse(int x) {

if (x == 0) return x;

long result = 0;

int xLen = String.valueOf(x).length();

for (int i = 0; i < xLen && x != 0; i++) {

result *= 10;

result += x % 10;

x /= 10;

}

if (result > Integer.MAX_VALUE || result < Integer.MIN_VALUE) result = 0;

return (int)result;

}

}