如何使用单个replaceAll查找Java中两个字符串共有的字符? [英] How do I find the characters common to two strings in Java using single replaceAll?
问题描述
所以假设我有:
String s = "1479K";
String t = "459LP";
我想回来
String commonChars = "49";
两个字符串之间的常用字符.
the common characters between the two strings.
很显然,可以使用以下标准循环进行操作:
Obviously it is possible to do with a standard loop like:
String commonChars = "";
for (i = 0; i < s.length; i++)
{
char ch = s.charAt(i);
if (t.indexOf(ch) != -1)
{
commonChars = commonChars + ch;
}
}
但是,我希望能够使用replaceAll
在一行中执行此操作.可以按照以下步骤进行操作:
However I would like to be able to do this in one line using replaceAll
. This can be done as follows:
String commonChars = s.replaceAll("["+s.replaceAll("["+t+"]","")+"]","");
我的问题是:是否可以使用replaceAll
的单次调用来做到这一点?正则表达式是什么?我想我必须使用某种先行方式,但是当我想到它时,我的大脑就会变得糊涂.
My question is: is it possible to do this using a single invocation of replaceAll
? And what would be the regular expression? I presume I have to use some sort of lookahead, but my brain turns to mush when I even think about it.
推荐答案
String commonChars = s.replaceAll("[^"+t+"]","");
请注意,您可能需要在t
中转义特殊字符,例如使用Pattern.quote(t)
而不是上面的t
.
Note that you may need to escape special characters in t
, e.g. using Pattern.quote(t)
instead of t
above.
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