原题链接: https://oj.leetcode.com/problems/reverse-integer/

public int reverse(int x) {
    String str = Integer.toString(x);
    StringBuilder sb = new StringBuilder(str.length());
    char c;

    if (str.indexOf('-') == 0) {
        sb.append('-');
    }
    for (int i = str.length() - 1; i >= 0; i--) {
        c = str.charAt(i);

        if (c == '-') {
            break;
        }

        sb.append(c);
    }

    return Integer.parseInt(sb.toString());
}