Question

我需要在斜杠“ /”之后获取某个字符串值，但是由于字符串的格式值并不总是相同，因此我遇到了麻烦。

字符串的值是ff：

String raw = "Announcements/announcement_id)";

我这里需要的只是 announcement_id ，可以使用lastIndexOf("/")+1获得，但这并不总是字符串的格式，它也可能像这样。

String raw = "Announcements/announcement_id/Comments/comment_id)";

这里我需要的都是 announcement_id 和 comment_id 。

最后一部分的字符串值也可能是这样。

String raw = "Announcements/announcement_id/Comments/comment_id/Replies/reply_id)";

这里我需要的都是 comment_id 和 reply_id 。

如何正确使用if else语句？

if(has only one slash)
   use lastIndexOf("/")+1 to get the id

else if (has three or more slashes)
   get the value after second to the last forward slash and last forward slash

Answer 1

您可以使用此正则表达式，该正则表达式允许字符串中的可选部分并适当地捕获announcement_id，comment_id和reply_id

(?:Announcements/([^/]*))(?:/Comments/([^/]*))?(?:/Replies/([^/]*))?\)

分别可以通过组1，组2或组3进行访问。

由于每个部分都是可选的，因此它允许您有选择地具有reply_id而无需commend_id，并且根据您的示例，我已将announcement_id强制设置为强制性，甚至您可以将其设置为可选。

Demo

查看此示例Java代码，

List<String> list = Arrays.asList("Announcements/announcement_id)",
        "Announcements/announcement_id/Comments/commend_id)",
        "Announcements/announcement_id/Comments/comment_id/Replies/reply_id)");

Pattern p = Pattern.compile("(?:Announcements/([^/]*))(?:/Comments/([^/]*))?(?:/Replies/([^/]*))?\\)");

list.forEach(x -> {
    Matcher m = p.matcher(x);
    if (m.matches()) {
        System.out.println("For string '" + x + "' --> announcement_id: " + m.group(1) + ", commend_id: "
                + m.group(2) + ", reply_id: " + m.group(3));
    }
});

根据找到的内容适当打印数据，

For string 'Announcements/announcement_id)' --> announcement_id: announcement_id, commend_id: null, reply_id: null
For string 'Announcements/announcement_id/Comments/commend_id)' --> announcement_id: announcement_id, commend_id: commend_id, reply_id: null
For string 'Announcements/announcement_id/Comments/comment_id/Replies/reply_id)' --> announcement_id: announcement_id, commend_id: comment_id, reply_id: reply_id

Answer 2

您的pathParams顺序是预先定义的，因此请使用split并解析数组。

 String s = "Announcements/announcement_id/Comments/comment_id/Replies/reply_id)";
 String [] pathParams = s.split("/");

Answer 3

String s = "Announcements/announcement_id/Comments/comment_id/Replies/reply_id";
String[] h = s.split("\\/");
switch (h.length) {
case 2:
    System.out.println(h[1]);
    break;
case 4:
    System.out.println(h[1] + " " + h[3]);
    break;
case 6:
    System.out.println(h[3] + " " + h[5]);
    break;
default:
    break;

}

此代码还提供了一种在拆分后如何继续以及访问所需元素的方法

Answer 4

以下方法适用于更多路径

String s = "Announcements/announcement_id/Comments/comment_id/Replies/reply_id)";
String[] paths = s.split("/");

if (paths.length % 2 == 0) {
  if (paths.length == 2) {
    System.out.println(paths[1]);
  } else {
    int lastPos = paths.length - 1;
    int beforeLastPos = lastPos - 2;
    System.out.println(paths[beforeLastPos] + " " + paths[lastPos]);
  }
}

（Java）在倒数第二个斜杠和最后一个斜杠之后获取String值

4 个答案: