Need help in identifying the correct regex format - regex

Question

I am learning regex and am working on finding the regex format to satisfy below conditions:
check the contents in between "<NoteText>" and "</NoteText>"
If there is one or more "<" symbol not followed by "!", return all the identified "<" symbols.
example:
<NoteText><![CDATA[dvsdhjkndlv <<<RED>>> <72901> </NoteText>
this should return the 3 "<" before RED and the 1 "<" before 72901
initially i tried with the below regex pattern of negative lookahead.
<(?!!)
But it returns the "<" before the "NoteText" phrase as well.
I am not sure how to limit the area of filtering in between "<NoteText>" and "</NoteText>".
trying the below way did not work as well.
(?:<NoteText>.*)(<(?!!)).*(?:<\/NoteText>)

Answer 1

PCRE, not pretty, but working:
(?:\G(?!\A)|<NoteText>)(?:(?!<\/?NoteText>).)*?\K<(?!!)(?=(?:(?!<\/?NoteText>).)*?<\/NoteText>)
See regex proof.
EXPLANATION
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(?: group, but do not capture:
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\G where the last m//g left off
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(?! look ahead to see if there is not:
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\A the beginning of the string
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) end of look-ahead
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| OR
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<NoteText> '<NoteText>'
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) end of grouping
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(?: group, but do not capture (0 or more times
(matching the least amount possible)):
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(?! look ahead to see if there is not:
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< '<'
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\/? '/' (optional (matching the most
amount possible))
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NoteText> 'NoteText>'
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) end of look-ahead
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. any character except \n
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)*? end of grouping
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\K match reset operator
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< '<'
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(?! look ahead to see if there is not:
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! '!'
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) end of look-ahead
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(?= look ahead to see if there is:
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(?: group, but do not capture (0 or more
times (matching the least amount
possible)):
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(?! look ahead to see if there is not:
--------------------------------------------------------------------------------
< '<'
--------------------------------------------------------------------------------
\/? '/' (optional (matching the most
amount possible))
--------------------------------------------------------------------------------
NoteText> 'NoteText>'
--------------------------------------------------------------------------------
) end of look-ahead
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. any character except \n
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)*? end of grouping
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< '<'
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\/ '/'
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NoteText> 'NoteText>'
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) end of look-ahead

Answer 2

This is a working method in Java 8. Remember that this works only if you don't have nested <NoteText> tags.
String myString = "<NoteText><![CDATA[dvsdhjkndlv <<<RED>>> <72901> </NoteText>";
Matcher outerMatcher = Pattern.compile("(?<=<NoteText>).*?(?=</NoteText>)").matcher(myString);
while (outerMatcher.find()) {
String content = outerMatcher.group(); // this is the content of the current NodeText tag
Matcher innerMatcher = Pattern.compile("<(?!!)").matcher(content);
int count = 0;
while (innerMatcher.find()) count++;
System.out.println(count); // this will print 4
}
The code above is thought for working also with strings of multiple occurrences of <NoteText> tags.
If you know you have only one <NoteText> tag, just replace the while with an if.