Question

I’m trying to figure out a regex pattern to use with the Java String.replaceAll() function. I need to replace all the %26 but I don’t want it to pick up any other numbers with a ’26’ prefix.

For example I want:

"abc%26def".replaceAll(regex, "&") to return "abc&def"

– and –

"abc%2623def".replaceAll(regex, "&") to return "abc%2623def"  (no change)

I’m aware I can easily write a few more lines of code to accomplish this task but I was wondering if it’s possible to do this with just a single replaceAll.

Answer 1

You can use a negative lookahead assertion that prevents matches where %26 is followed by another digit (you’ll need to escape the \ in Java, so it would be \\d):

%26(?!\d)

• Regex Demo: http://www.rubular.com/r/J07zojxabd
• Java Demo: http://ideone.com/luCmFN