Java String.replaceFirst (), which takes an argument from the beginning

Question

I need to replace the word in a line similar to "duh duh something else duh". I only need to replace the second "duh", but the first and last should remain intact, so replace () and replaceFirst () do not work. Is there a method like replaceFirst (String regex, String replacement, int offset) that would replace the first substitution starting at the offset, or maybe you would recommend another way to solve this? Thanks!

Answer 1

Something like that:

String replaceFirstFrom(String str, int from, String regex, String replacement) { String prefix = str.substring(0, from); String rest = str.substring(from); rest = rest.replaceFirst(regex, replacement); return prefix+rest; } // or s.substring(0,start) + s.substring(start).replaceFirst(search, replace); 

just 1 line of code ... not the whole method.

Answer 2

Will there be something like this work?

  System.out.println( "1 duh 2 duh duh 3 duh" .replaceFirst("(duh.*?)duh", "$1bleh") ); // prints "1 duh 2 bleh duh 3 duh" 

If you just want to replace the second occurrence of the pattern in a string, you really don't need this “starting with” index calculation.

As a bonus, if you want to replace all other duh (i.e. second, fourth, sixth, etc.), just call replaceAll instead of replaceFirst .

Answer 3

Alternative using Matcher :

  String input = "duh duh something else duh"; Pattern p = Pattern.compile("duh"); Matcher m = p.matcher(input); int startIndex = 4; String output; if (m.find(startIndex)) { StringBuffer sb = new StringBuffer(); m.appendReplacement(sb, "dog"); m.appendTail(sb); output = sb.toString(); } else { output = input; }