找到所有匹配的子串，而不仅仅是“最大的”子串。一

问题描述

代码

String s = "y z a a a b c c z";
Pattern p = Pattern.compile("(a )+(b )+(c *)c");
Matcher m = p.matcher(s);
while (m.find()) {
    System.out.println(m.group());
}

打印

a a a b c c

这是对的。

但从逻辑上讲，子串

a a a b c
a a b c c
a a b c
a b c c
a b c

也匹配正则表达式。

那么，我怎样才能让代码找到那些子串呢，即不仅是最扩展的，还有 children ？

So, how can I make the code find those substrings too, i.e. not only the most extended one, but also its children?

推荐答案

您可以使用，例如 *？和 +？ 。这些匹配尽可能少，与标准的 * 和 + 形成鲜明对比，这些都是贪婪的，即尽可能匹配可能。尽管如此，这只允许您找到特定的子匹配，而不是全部。使用前瞻控制非捕获组可以实现更多控制，也在文档中描述。但是为了真正找到所有子匹配，你可能必须自己做一些事情，即构建正则表达式对应的自动机，并使用自定义代码导航它。

You can use the reluctant qualifiers such as *? and +?. These match as little as possible, in contrast to the standard * and + which are greedy, i.e. match as much as possible. Still, this only allows you to find particular "sub-matches", not all of them. Some more control can be achieved using lookahead controlling non-capturing groups, also described in the docs. But in order to really find all sub-matches, you would probably have to do stuff yourself, i.e. build the automaton to which the regex corresponds and navigate it using custom code.

这篇关于找到所有匹配的子串，而不仅仅是“最大的”子串。一的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！