CODEWITHSUNDEEP
javaregexstring
user2816352
user2816352

Reputation: 335

Java Regex - whitespace & matching words

I'm new to Regex but I think my problem should be solved using it. Basically, I want to replace whitespace in a string with "dog", as long as the words "cat" or "bird" or "dog" aren't before or after.

Example:

    Good Dog = Good Dog
    Large Brown = Large Dog Brown
    Cat Ugly = Cat Ugly

So only the second string would be modified. I can handle something like this easily string replace etc, but i'm curious to know if this should be done in regex.

Upvotes: 2

Views: 101

Answers (1)

Pshemo
Pshemo

Reputation: 124225

You are looking for lookaround mechanisms. Your code can look more or less like 

yourString = yourString.replaceAll("(?<!cat|bird|dog)\\s(?!cat|bird|dog)"," dog ")
//                                  ^^^^^^^^^^^^^^^^^   ^^^^^^^^^^^^^^^^
//                               negative look-behind   negative look-ahead

You can improve this regex by making it case insensitive with (?i) flag.
You can also add word boundaries (\b) to make sure you are matching whole words, and not only its parts like cataclysm.

Demo (I also used non-capturing group (?:...) to increase performance a little):

String[] data ={ "Good Dog", "Large Brown", "Cat Ugly"};
for (String s : data){
    System.out.println(s.replaceAll("(?i)(?<!\\b(?:cat|bird|dog)\\b)\\s(?!\\b(?:cat|bird|dog)\\b)"," dog "));
}

Output:

Good Dog
Large dog Brown
Cat Ugly

Upvotes: 4

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