Replace word using java regex but not quotes

Question

I want to replace a word in a sentence using java regex replace.

test string is a_b a__b a_bced adbe a_bc_d 'abcd' ''abcd''

if i want to replace all the words which starts with a & ends with d. i'm using String.replaceAll("(?i)\\ba[a-zA-Z0-9_.]*d\\b","temp").

its replacing as a_b a__b temp adbe a_bc_d 'temp' ''temp''

What should be my regex if i don't want to consider the string in quotes.?

I used String.replaceAll("[^'](?i)\\ba[a-zA-Z0-9_.]*d\\b[^']","temp") Its replacing as a_b a__btempadbe temp'abcd' ''abcd''. Its removing one spaces of that word. Is there any way to replace only that string not inside the quotes?

PS: there is a workaround for this String.replaceAll("[^'](?i)\\ba[a-zA-Z0-9_.]*d\\b[^']"," temp "). But it fails in some cases.

What should be my regex if i want to replace a word in a sentence & i should not consider string in side quotes.? Thanks in Advance...!!!

Answer 1

You can use lookaround assertions:

string = string.replaceAll("(?i)(?<!')\\ba[a-zA-Z0-9_.]*d\\b(?!')", "temp");

RegEx Demo

Read more about lookarounds

RegEx Details:

• (?i): Turn mode to ignore case
• (?<!'): Negative lookbehind to make sure there is no ' right before the current position
• \b: Word boundary
• a[a-zA-Z0-9_.]*: Match letter a followed by 0 or more of any character inside the character class [...]
• d: Match letter d
• \b: Word boundary
• (?!'): Negative lookahead to make sure there is no ' right after the current position