Using java's regex api to insert words be

I'm new to regular expressions and java so please bear with my newbish question.

I want to do the following:

If I have a string:

"I like ice cream only if it is chocolate ice cream. Chocolate cream" 

and a pattern like

"chocolate ice cream" 

I want to match and replace all words matched with a # surrounding them. Like this:

"I like #ice cream# only if it is #chocolate ice cream#. #Cholcolate cream#"

I used java's regex api and I understand I can use Matcher.replaceAll. But I'm having trouble coming up with a proper regex. I came up with this chocolate*\\s*ice*\\s*cream*. But the problem here is it's only matching the whole substring, i.e "chocolate ice cream". I think something like this could work:

chocolate|ice|cream|chocolate ice|ice cream|chocolate cream|chocolate ice cream

etc, i.e all permutations, but this would be cumbersome as the substring grows.

I would appreciate any ideas on proceeding in the right dire开发者_JAVA技巧ction.

Use the pattern:

(?i)\b((?:chocolate|ice|cream)(?:\s+(?:chocolate|ice|cream))*)\b

and replace it with:

#$1#

Demo:

String s = "I like ice cream only if it is chocolate ice cream. Chocolate cream";
s = s.replaceAll("(?i)\\b((?:chocolate|ice|cream)(?:\\s+(?:chocolate|ice|cream))*)\\b", "#$1#");
System.out.println(s);

The word boundaries cause "creamy" (and other such words) not to be replaced.

Note that this will change "ice ice" into "#ice ice#" (ie. the words can occur more than once!), as @stema mentioned in the comments.

(?:chocolate|ice|cream)(?:\s+(?:chocolate|ice|cream))*

This will match one or more of the specified words delimited by whitespace

Try this:

final String source = "I like ice cream only if it is chocolate ice cream. Chocolate cream";
final String result = source.replaceAll("((?:[Cc]hocolate )?(?:[Ii]ce )?cream)", "#$1#");

// Prints I like #ice cream# only if it is #chocolate ice cream#. #Chocolate cream#
System.out.println(result);

See Optional Items for more information.

Maybe you will find interesting MessageFormat from the Java API

Object[] testArgs = {new Long(3), "MyDisk"};

MessageFormat form = new MessageFormat(
  "The disk \"{1}\" contains {0} file(s).");

 System.out.println(form.format(testArgs));

 // output, with different testArgs
 output: The disk "MyDisk" contains 0 file(s).
 output: The disk "MyDisk" contains 1 file(s).
 output: The disk "MyDisk" contains 1,273 file(s).