java正则表达式匹配 [英] java regular expression matching

问题描述

Hi< Dog> Hi 和< Dog> 在给定的文本中。

更新：

什么正则表达式会匹配这个？

 < FONT FACE =VerdanaSIZE =16COLOR =＃0B333CLETTERSPACING =0KERNING = 0>如果您访问网站，请点击以下链接：< FONT SIZE =12>< / FONT>< / FONT> 
  

< FONT。*？< \ / FONT> code>仅匹配到第一个< / FONT>

解决方案

模式 ^（[az] *）< [AZ] *> \ 1 $ 将匹配这些字符串（在rubular.com上看到）：



  ab< XYZ> ab 
< XYZ> 
 bleh< FOO> bleh 
< 
  

它不会匹配这些：



 ab< XYZ> de 
 x< XYZ> y 
 FOO< foo> FOO 
< / code& 
 
 
也就是说，该模式类似于 
 
 
 
 
  标签  <内容>   标签  
 
 
同样的 标记  前缀和后缀。标签由零个或多个小写字母组成。内容由零个或多个大写字母组成。前缀部分被匹配，并且被组捕获，然后反向引用<$ c 
 
 
  [...] 用于匹配该字符串， / code>是字符类 。像 [aeiou] 之类的东西匹配任何小写元音之一。  [^ ...] 是一个否定的字符类。  [^ aeiou] 与中的任何一个匹配，而是小写元音。 
 
 
 Java字符串文字，模式是^（[az] *）< [AZ] *> \\ 1 $。  
What is the regular expression that can match the following 2 strings.


Hi<Dog>Hi and <Dog> in a given text.

Update:

What regex will match this one? 
<FONT FACE="Verdana" SIZE="16" COLOR="#0B333C" LETTERSPACING="0" KERNING="0">If you access the web site click the link below:<FONT SIZE="12"></FONT></FONT>
<FONT.*?<\/FONT> matches only till the first </FONT>
解决方案
The pattern ^([a-z]*)<[A-Z]*>\1$ will match these strings (as seen on rubular.com):
ab<XYZ>ab
<XYZ>
bleh<FOO>bleh
<>
It will not match these:
ab<XYZ>de
x<XYZ>y
FOO<foo>FOO
That is, the pattern is something like

  
tag<CONTENT>tag
The same tag appears for both the "prefix" and the "suffix". Tag consists of zero or more lowercase letters. Content consists of zero or more uppercase letters. The prefix part is matched and captured by group 1, and then a backreference \1 is used to match that string again for the suffix.

The […] is a character class. Something like [aeiou] matches one of any of the lowercase vowels. [^…] is a negated character class. [^aeiou] matches one of anything but the lowercase vowels.

As a Java string literal, the pattern is "^([a-z]*)<[A-Z]*>\\1$". 

                        
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