Leecode-7.整数反转

输入: 123
输出: 321

输入: -123
输出: -321

输入: 120
输出: 21

class Solution {
    public int reverse(int x) {
        boolean b = x >= 0;
        StringBuilder sb = new StringBuilder(String.valueOf(x));
        long l = b ? Long.valueOf(sb.reverse().toString()) :  Long.valueOf(sb.deleteCharAt(0).reverse().toString());
        if (l > Integer.MAX_VALUE || l < Integer.MIN_VALUE) {
            return 0;
        } else {
            return b ? Integer.valueOf(sb.toString()) : 0 - Integer.valueOf(sb.toString());
        }
    }
}