Regex pattern to replace the wrong placeholders with blank

Question

I want to replace a String which contains of placeholders which should only consists on digit.

For ex - this is the test string {0} with correct placeholder {1}.

Valid placeholders - {digits}
Invalid Placeholders - alphanumeric, empty, digit with whitespace, character with whitespace

Can anyone help me with a regex. I tried this but its not working -

\{((([^0-9]).+?)|(.([^0-9])+?))\}

Thank in advance!

Answer 1

You can use

\{(?!\d+\})[^{}]*\}

See the regex demo

Details

• \\{ - a { char
• (?!\\d+\\}) - a negative lookahead that fails the match if there are 1 or more digits and then a } char immediately to the right of the current location
• [^{}]* - 0 or more chars other than { and }
• \\} - a } char.