Remove text from String via Regexp

Question

in Java I want to remove some text from the following String via Regexp:

someText

begin
  .someMethod()
  .doSomething(TOKEN_123)
  .someMethod()
end

begin
  .someMethod()
  .doSomething(TOKEN_456)
  .someMethod()
end

begin
  .someMethod()
  .doSomething(TOKEN_789)
  .someMethod()
end

more Text

I want to remove the 2nd begin/end-Block which includes the String TOKEN_456.

Currently my regexp looks like the following

begin.*TOKEN_456(.*?)end

but this one removes the first AND second block.

Can anyone help please?

Greetz

I guess you have the singleline flag. Why not split by multiple newlines and remove the element of the resulting array, and then joining the rest? BTW, you are looking for `begin(?:(?!begin).)*TOKEN_456(.*?)end`. — Wiktor Stribiżew, Dec 04 '15 at 08:15
As I mentioned, the dupe was absolutely incorrect, it is not solved with negated character class or lazy dot matching, thus relieved the close vote. — Wiktor Stribiżew, Dec 04 '15 at 12:15

Wiktor Stribiżew · Accepted Answer · 2015-12-04T08:49:08.230

2

You can use

str = str.replaceFirst("(?s)begin(?:(?!begin).)*TOKEN_456.*?end\\s*", ""));

See the IDEONE demo and a regex demo.

The regex matches:

(?s) - a singleline modifier
begin - matches the leading boundary, a character sequence begin
(?:(?!begin).)* - a tempered greedy token that matches any text that is not starting the word begin
TOKEN_456 - a literal character sequence to match
.*?end - any number of any characters as few as possible, up to the closest end
\\s* - 0 or more whitespace (for trimming purposes).

edited Dec 04 '15 at 08:49

answered Dec 04 '15 at 08:18

Wiktor Stribiżew

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You can improve performance of the regex if you add more "anchoring" details, like word boundaries, start of *line* anchor, newlines: [`"(?sm)^begin\\b(?:(?!\\bbegin\\b).)*TOKEN_456(.*?)\nend(?:$|\n)"`](https://regex101.com/r/vN5vT7/2). – Wiktor Stribiżew Dec 04 '15 at 08:26
Just noticed a capturing group on `(.*?)` - I guess you can remove the parentheses if you are not interested in the captured text. – Wiktor Stribiżew Dec 04 '15 at 08:28
ah good to know. Thought I always have to use brackets in this context – Mike G Dec 04 '15 at 08:40

Remove text from String via Regexp

1 Answers1