LeetCode Palindrome Number

1. negative is not palindrome number
2. use double to avoid the overflow.

public boolean isPalindrome(int x) {
        if (x < 0) return false;
        if (x == 0) return true;
        double rev = 0;
        int y = x; //don't forget to save the original number before you do some operation.
        while (x != 0) {
            rev = rev * 10 + x%10;
            x /= 10;
        }
        if (rev > Integer.MAX_VALUE) {
            return false;
        }
     
        return (int)rev == y ;
    }