在字符串中找出连续最长的数字串

1. 常规思路

    遍历一次，和之前的数字字符串比较长度，找到最长的

/**
 * @param str 输入的字符串
 */
public void getLongestNumString(String str) {
    char[] arr = str.toCharArray();
    StringBuilder tmp = new StringBuilder();
    String ret = "";
    List<String> list = new ArrayList<>();
    boolean isConsecutive = false;
    for (char ch : arr) {
        if (Character.isDigit(ch)) {
            if (!isConsecutive) {
                tmp = new StringBuilder();
            }
            tmp.append(ch);
            isConsecutive = true;
            if (ret.length() < tmp.toString().length()) {
                ret = tmp.toString();
                list.clear();
                list.add(ret);
            } else if (ret.length() == tmp.toString().length()) {
                list.add(tmp.toString());
            }
        } else {
            isConsecutive = false;
        }
    }

    for (String string : list) {
        System.out.print(string);
    }
    System.out.print(","+ret.length());
    System.out.println();
}

2. 其他思路

来源：https://www.nowcoder.com/questionTerminal/2c81f88ecd5a4cc395b5308a99afbbec?f=discussion 哎呀哎呀123 的回答

（利用正则表达式）将所有非数字的字符转换成一个字母，然后按照这个字母进行分隔，最后找到最长的数字串

/**
 * private static final String REPLACE_LETTER = "a";
 *
 * @param str 输入的字符串
 */
public void getLongestNumString(String str) {
    if (str == null || str.length() == 0) {
        System.out.println(0);
        return;
    }

    str = str.replaceAll("\D+", REPLACE_LETTER);
    String[] arr = str.split(REPLACE_LETTER);

    int maxLength = -1;
    for (String tmp : arr) {
        if (tmp.length() > maxLength) {
            maxLength = tmp.length();
        }
    }

    for (String tmp : arr) {
        if (tmp.length() == maxLength) {
            System.out.print(tmp);
        }
    }

    System.out.println("," + maxLength);
}