[英]Regular expression to find return of character for 5 times
I'm trying to build a finite state machine and I want to check the sequence that I get, with a regular expression.我正在尝试构建一个有限状态机,我想用正则表达式检查我得到的序列。 I need to check if the sequence is from the the following form:我需要检查序列是否来自以下形式:
For example:例如:
"A,B,C,C,C,C,C,A"
-> is accepted. "A,B,C,C,C,C,C,A"
-> 被接受。
"A,B,C,C,C,C,A"
-> is ignored. "A,B,C,C,C,C,A"
-> 被忽略。
"A,B,C,C,C,C,C,C,A"
-> is ignored. "A,B,C,C,C,C,C,C,A"
-> 被忽略。
I found this post and that post , but everything I tried simply doesn't work.我找到了这个帖子和那个帖子,但是我尝试的所有方法都不起作用。
I tried the next things: A\\B\\D{5}\\A
, ABD{5}A
and a couple more, but again with no success.我尝试了接下来的事情: A\\B\\D{5}\\A
、 ABD{5}A
和更多,但同样没有成功。
EDIT: I want to know if the C character is return exactly 5 times, before and after doesn't matter at all, meaning it could be like this also:编辑:我想知道 C 字符是否正好返回 5 次,前后都无关紧要,这意味着它也可能是这样的:
A,A,A,F,F,R,E,D,C,C,C,C,C, ...... A、A、A、F、F、R、E、D、C、C、C、C、C、......
Don't consider the commas.不要考虑逗号。
The problem is that I need to find if a sequence is accepted but, the sequence is from the next form: A,B, C*10, I created the machine class, the state class and the event class.问题是我需要找到一个序列是否被接受,但是,该序列来自下一个形式:A、B、C*10,我创建了机器类、状态类和事件类。 But now I need to know if I have exactly 5 returns of C, and it causing me a lot of problems.但是现在我需要知道我是否正好有 5 个 C 返回,这给我带来了很多问题。
EDIT: It's not working, see the code Iv'e added.编辑:它不起作用,请参阅我添加的代码。
String sequence1 = "A,B,C,C,C,C,A";
String sequence2 = "A,B,C,C,C,C,C,A";
String sequence3 = "A,B,C,C,C,C,C,C,A";
Pattern mPattern = Pattern.compile("(\\w)(?:,\\1){4}");
Matcher m = mPattern.matcher(sequance1);
m.matches(); //FALSE
Matcher m = mPattern.matcher(sequance2);
m.matches(); //FALSE
Matcher m = mPattern.matcher(sequance3);
m.matches(); //FALSE
It's returning always false.它返回总是假的。
How can I achieve this?我怎样才能做到这一点?
Thanks.谢谢。
Your regex is not working because you are not considering the comma in your string, which I assume is available.您的正则表达式不起作用,因为您没有考虑字符串中的逗号,我认为它是可用的。
You can try the following regex (I'm posting here a generalized pattern, you can modify it accordingly): -您可以尝试以下正则表达式(我在这里发布了一个通用模式,您可以相应地修改它):-
"(\\w)(?:,\\1){4}"
This will match any 5 sequence of same characters separated by comma.这将匹配由逗号分隔的任何 5 个相同字符序列。
\\1
is used to backreference the 1st matched character, and the rest of the 4 characters should be the same as that. \\1
用于反向引用第一个匹配的字符,其余 4 个字符应与此相同。
Explanation: -解释: -
"( // 1st capture group
\\w // Start with a character
)
(?: // Non-capturing group
, // Match `,` after `C`
\\1 // Backreference to 1st capture group.
// Match the same character as in (\\w)
){4}" // Group close. Match 4 times
// As 1st one we have already matched in (\\w)
UPDATE: -更新: -
If you just want to match 5 length
sequence, you can add a negation of the matched character after the 5th match: -如果你只想匹配5 length
序列,你可以在第 5 个匹配之后添加一个匹配字符的否定:-
"(\\w)(?:,\\1){4}(?!,\\1)"
(?!,\\\\1)
-> Is negative look-ahead assertion. (?!,\\\\1)
-> 是否定的前瞻断言。 It will match 5 consecutive character that are not followed by the same character.它将匹配后面没有同一个字符的 5 个连续字符。
UPDATE: -更新: -
In the above Regex, we also need to do a negative look-behind for \\\\1
which we can't do.在上面的正则表达式中,我们还需要对\\\\1
进行负向后视,这是我们无法做到的。 So, I came up with this wierd looking Regex.所以,我想出了这个看起来很奇怪的正则表达式。 Which I myself don't like, but you can try it whether it works or not: -我自己不喜欢它,但不管它是否有效,您都可以尝试:-
Not Tested : -未测试:-
"(\\w),(^\\1)(?:,\\2){4}(?!,\\2)"
Explanation: -解释: -
( // First Capture Group
\\w // Any character, before your required sequence. (e.g. `A` in `A,C,C,C,C,C`)
) // Group end
, // comma after `A`
( // Captured group 2
^\\1 // Character other than the one in the first captured group.
// Since, We now want sequence of `C` after `A`
)
(?: // non-capturing group
, // Match comma
\\2 // match the 2nd capture group character. Which is different from `A`,
// and same as the one in group 2, may be `C`
){4} // Match 4 times
(?! // Negative look-ahead
,
\\2 // for the 2nd captured group, `C`
)
I don't know whether that explanation makes the most sense or not.我不知道这种解释是否最有意义。 But you can try it.但是你可以试试。 If it works, and you can't understand, then I'll try to explain a little better.如果它有效,而你无法理解,那么我会尝试解释得更好一点。
I don't understand what you have tried, but you don't need to escape letters to match them.我不明白你试过什么,但你不需要转义字母来匹配它们。
I am not sure what your requirements are, but to find 5 repeated characters you can use this:我不确定您的要求是什么,但是要找到 5 个重复的字符,您可以使用它:
(\\p{L})(?:,\\1){4}
This would find all letters that are repeated 5 times.这将找到所有重复 5 次的字母。 See it here on Regexr .在 Regexr 上查看这里。
On Regexr I used \\w
because \\p{L}
is not supported there, but it is in Java.在 Regexr 上,我使用了\\w
因为那里不支持\\p{L}
,但它是在 Java 中使用的。
\\p{L}
is a Unicode property matching every letter in any language. \\p{L}
是一个 Unicode 属性,匹配任何语言中的每个字母。
The idea here is to match a letter.这里的想法是匹配一个字母。 This is done by \\\\p{L}
.这是由\\\\p{L}
。
This letter is stored in a backreference because there are the brackets around (\\\\p{L})
.该字母存储在反向引用中,因为(\\\\p{L})
周围有括号。
Then there is the non-capturing group (?:,\\\\1)
.然后是非捕获组(?:,\\\\1)
。 This matches a comma and the \\\\1
is a reference to the letter captured before.这匹配一个逗号,而\\\\1
是对之前捕获的字母的引用。
This non-capturing group is repeated 4 times (?:,\\\\1){4}
.这个非捕获组重复 4 次(?:,\\\\1){4}
。
==> as result this pattern matches on 5 identical letters with commas between. ==> 结果这个模式匹配 5 个相同的字母,中间有逗号。
The problem here is, this expression will match at least 5 identical letters.这里的问题是,这个表达式将匹配至少 5 个相同的字母。 If there are more of them it will also (partly) match.如果有更多,它也将(部分)匹配。
Update:更新:
I don't see a chance to get the result directly from a regex.我看不到直接从正则表达式获得结果的机会。 But here is a method to get the length indirectly:但这是一种间接获取长度的方法:
String[] TestInput = { "A,B,C,C,C,C,C", "A,B,C,C,C,C,C,D,E",
"C,C,C,C,C", "C,C,C,C,C,D,E", "A,B,C,C,C,C", "C,C,C,C",
"A,B,C,C,C,C,C,C,D,E", "C,C,C,C,C,C,D,E", "C,C,C,C,C,C" };
// Match at least 5 letters in a row
// The letter is in group 2
// The complete found sequence is in group 1
Pattern p = Pattern.compile("((\\p{L})(?:,\\2){4,})");
for (String t : TestInput) {
Matcher m = p.matcher(t);
if (m.find()) {
// Get the length of the found sequence, after the commas has
// been removed
int letterLength = m.group(1).toString().replace(",", "")
.length();
// Check your condition of exactly 5 equal letters
if (letterLength == 5) {
System.out.println(t + " ==> " + true);
} else {
System.out.println(t + " ==> " + false);
}
}else {
System.out.println(t + " ==> " + false);
}
}
Output:输出:
A,B,C,C,C,C,C ==> true A,B,C,C,C,C,C ==> 真
A,B,C,C,C,C,C,D,E ==> true A、B、C、C、C、C、C、D、E ==> 真
C,C,C,C,C ==> true C,C,C,C,C ==> 真
C,C,C,C,C,D,E ==> true C、C、C、C、C、D、E ==> 真
A,B,C,C,C,C ==> false A,B,C,C,C,C ==> 假
C,C,C,C ==> false C,C,C,C ==> 假
A,B,C,C,C,C,C,C,D,E ==> false A、B、C、C、C、C、C、C、D、E ==> 假
C,C,C,C,C,C,D,E ==> false C、C、C、C、C、C、D、E ==> 假
C,C,C,C,C,C ==> false C,C,C,C,C,C ==> 假
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