CODEWITHSUNDEEP
javaregexcomments
hyde
hyde

Reputation: 2585

Java: Strip Slashes and Stars from Block Comments using Regex

I am working on a personal project where I need to extract the actual comments from an input string like this.

Case 1: /* Some useful text */

Output: Some useful text

Case 2: /*** This is formatted obnoxiously**/

Output: This is formatted obnoxiously

Case 3: 

    /**

    More useful
information

    */

Output: More useful information

Case 4:

/**
Prompt the user to type in 
the number. Assign the number to v
*/

Output: Prompt the user to type in the number. Assign the number to v

I am working in Java and I have tried to replace /* and */ using naive method such as String.replace but since a comment can be formatted in different ways like above, the replace method seems not to be a viable approach to do this. How can I achieve the above outputs using regex?

Here is the test comment file that I am using.

Upvotes: 0

Views: 2635

Answers (2)

Keppil
Keppil

Reputation: 46209

You can use the following regex: 

String newString = oldString.replaceAll("/\\*+\\s*|\\s*\\*+/", "");

EDIT

To also get rid of newlines you could do something like: 

String regex = "/\\*+\\s*|\\s*\\*+/|[\r\n]+";
String newString = oldString.replaceAll(regex, "");

Upvotes: 1

Stephan
Stephan

Reputation: 8090

Try something like :

"/\\*+\\s*(.*?)\\*+/"

And dot should match also new lines:

Pattern p = Pattern.compile("/\\*+\\s*(.*?)\\*+/", Pattern.DOTALL);

EDIT

 Pattern p = Pattern.compile("/\\*+\\s*(.*?)\\*+/", Pattern.DOTALL); 
 Matcher m = p.matcher("/*** This is formatted obnoxiously**/");
 m.find();
 String sanitizedComment = m.group(1); 
 System.out.println(sanitizedComment);

Upvotes: 2

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