Regular expression to replace content parentheses and their contents

Question

I am looking for a regular expression that will replace parentheses and the strings within them if the string anything that is not a digit.

The string can be any combination of characters including numbers, letters, spaces etc.

For example:

(3) will not be replaced

(1234) will not be replaced

(some letters) will be replaced

(some letters, spaces - and numbers 123) will be replaced

So far I have a regex that will replace any parentheses and its content

str = str.replaceAll("\\(.*?\\)","");

Answer 1

I am not good with the syntax of replaceAll, so I am just going to write the way you have written it. But I think I can help you with the regex.

Try this Regex:

\((?=[^)]*[a-zA-Z ])[^)]+?\)

Demo

OR an even better one:

\((?!\d+\))[^)]+?\)

Demo

Explanation(for 1st Regex)

• \( - matches opening paranthesis
• (?=[^)]*[a-zA-Z ]) - Positive Lookahead - checks for 0 or more of any characters which are not ) followed by a space or a letter
• [^)]+? - Captures 1 or more characters which are not )
• \) - Finally matches the closing Paranthesis

Explanation(for 2nd Regex)

• \( - matches opening paranthesis
• (?!\d+\)) - Negative Lookahead - matches only those strings which do not have ALL the characters as digits after the opening paranthesis but before the closing paranthesis appears
• [^)]+? - Captures 1 or more characters which are not )
• \) - Finally matches the closing Paranthesis

Now, you can try your Replace statement as:

str = str.replaceAll("\((?=[^)]*[a-zA-Z ])[^)]+?\)","");

OR

str = str.replaceAll("\((?!\d+\))[^)]+?\)","");