How to substitute blanks between certain patterns using regex-CodePudding

I want to substitute the blanks between the $# and the ending #.

Test String:

This is my variable A $#testpattern 1# and this is variable B $#testpattern 2 with multiple blanks#

Expected result:

This is my variable A $#testpattern1# and this is variable B $#testpattern2withmultipleblanks#

I got it to work when it only has one blank but with more than one it does not work.

Current Regex:

/(?<=\$#)(\w*?)(\s*?)(\w*?)(?=#)

CodePudding user response：

Java supports a finite quantifier in a lookbehind assertion, so you can add optional word characters or spaces to it [\w\s]{0,100} and for the lookahead you can add only [\w\s]* matching 1 or more whitespace characters in between.

(?<=\$#[\w\s]{0,100})\s (?=[\w\s]*#)

For example

String string = "This is my variable A $#testpattern 1# and this is variable B $#testpattern 2 with multiple blanks#";
System.out.println(string.replaceAll("(?<=\\$#[\\w\\s]{0,100})\\s (?=[\\w\\s]*#)", ""));

Output

This is my variable A $#testpattern1# and this is variable B $#testpattern2withmultipleblanks#

See a Java demo and a Regex demo.

CodePudding user response：

Here is one way to do it.

\\$#(.*?)# - capture string between delimiters
find each capture group in the pattern.
remove the blanks in that group.
then in the original string, replace the captured string with the modified string.

String s = "This is my variable A $#testpattern 1# and this is variable B $#testpattern 2 with multiple blanks#";

Pattern p = Pattern.compile("\\$#(.*?)#");
Matcher m =p.matcher(s);
while (m.find()) {
    String str = m.group(1).replace(" ","");
    s = s.replace(m.group(1),str);
}
System.out.println(s);

prints

This is my variable A $#testpattern1# and this is variable B $#testpattern2withmultipleblanks#