Question

必须使用正则表达式在java中编写我需要在"what is"之后打印一个单词输入：

So what is java regex
what is operator in java

输出：

java
operator

Answer 1

只需使用一个lookbehind来匹配一个字符串，该字符串紧跟在与lookbehind内部模式匹配的字符串之后。

(?<=what is )\\S+

OR

(?<=what\\sis\\s)\\S+

代码：

String s = "So what is java regex\n" + 
        "what is operator in java";
Pattern regex = Pattern.compile("(?<=what is )\\S+");
 Matcher matcher = regex.matcher(s);
 while(matcher.find()){
        System.out.println(matcher.group(0));
}

输出：

java
operator

Answer 2

如果必须是正则表达式，我会保持简单并使用capturing group来匹配并捕获“what is”之后的单词

what\sis\s(\w+)

注意：您需要引用匹配组#1来返回匹配结果。

说明：

what       # 'what'
\s         # whitespace (\n, \r, \t, \f, and " ")
is         # 'is'
\s         # whitespace (\n, \r, \t, \f, and " ")
(          # group and capture to \1:
  \w+      #   word characters (a-z, A-Z, 0-9, _) (1 or more times)
)          # end of \1

如何使用正则表达式在短语后打印单词

2 个答案: