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

 1 /**
 2  * @param str 输入的字符串
 3  */
 4 public void getLongestNumString(String str) {
 5     char[] arr = str.toCharArray();
 6     StringBuilder tmp = new StringBuilder();
 7     String ret = "";
 8     List<String> list = new ArrayList<>();
 9     boolean isConsecutive = false;
10     for (char ch : arr) {
11         if (Character.isDigit(ch)) {
12             if (!isConsecutive) {
13                 tmp = new StringBuilder();
14             }
15             tmp.append(ch);
16             isConsecutive = true;
17             if (ret.length() < tmp.toString().length()) {
18                 ret = tmp.toString();
19                 list.clear();
20                 list.add(ret);
21             } else if (ret.length() == tmp.toString().length()) {
22                 list.add(tmp.toString());
23             }
24         } else {
25             isConsecutive = false;
26         }
27     }
28 
29     for (String string : list) {
30         System.out.print(string);
31     }
32     System.out.print(","+ret.length());
33     System.out.println();
34 }

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

 1 /**
 2  * private static final String REPLACE_LETTER = "a";
 3  *
 4  * @param str 输入的字符串
 5  */
 6 public void getLongestNumString(String str) {
 7     if (str == null || str.length() == 0) {
 8         System.out.println(0);
 9         return;
10     }
11 
12     str = str.replaceAll("\D+", REPLACE_LETTER);
13     String[] arr = str.split(REPLACE_LETTER);
14 
15     int maxLength = -1;
16     for (String tmp : arr) {
17         if (tmp.length() > maxLength) {
18             maxLength = tmp.length();
19         }
20     }
21 
22     for (String tmp : arr) {
23         if (tmp.length() == maxLength) {
24             System.out.print(tmp);
25         }
26     }
27 
28     System.out.println("," + maxLength);
29 }