Java中的非贪婪正则表达式 [英] Non-greedy Regular Expression in Java

问题描述

我有下一个代码:

public static void createTokens(){
    String test = "test is a word word word word big small";
    Matcher mtch = Pattern.compile("test is a (\\s*.+?\\s*) word (\\s*.+?\\s*)").matcher(test);
    while (mtch.find()){
        for (int i = 1; i <= mtch.groupCount(); i++){
            System.out.println(mtch.group(i));
        }
    }
}

并具有下一个输出:

word
w

但是我认为它必须是:

word
word

请有人向我解释为什么?

Somebody please explain me why so?

推荐答案

由于您的模式不贪心，因此它们在仍由匹配项组成的情况下，尽可能少地匹配文本.

Because your patterns are non-greedy, so they matched as little text as possible while still consisting of a match.

删除?在第二组中，您会得到
字
词词大小

Remove the ? in the second group, and you'll get
word
word word big small

Matcher mtch = Pattern.compile("test is a (\\s*.+?\\s*) word (\\s*.+\\s*)").matcher(test);

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